Bioengineering

8 pages, 2629 KiB

Open AccessCommunication

Assessment of the Inner Surface Microstructure of Decellularized Cortical Bone by a Scanning Electron Microscope

by Heonuk Jeong, Jungo Asai, Takashi Ushida and Katsuko S. Furukawa

Bioengineering 2019, 6(3), 86; https://doi.org/10.3390/bioengineering6030086 - 19 Sep 2019

Cited by 9 | Viewed by 6406

The microstructural changes of bones, which form a hierarchy of skeletal tissue, vary, depending on their condition, and are affected by the behaviors of bone cells. The purpose of this study is to assess the microstructural changes in the inner femoral surface of [...] Read more.

The microstructural changes of bones, which form a hierarchy of skeletal tissue, vary, depending on their condition, and are affected by the behaviors of bone cells. The purpose of this study is to assess the microstructural changes in the inner femoral surface of Sprague Dawley rats according to the conditions using a scanning electron microscope. Microstructural differences on the endocortical surface were observed in the characteristics of osteocytic canaliculi, bone fibers, and surface roughness, showing a rougher surface in old adults and an osteoporosis model by quantitative comparison. These results could be helpful for developing a basic understanding of the microstructural changes that occur on the bone surface under various conditions. Full article

(This article belongs to the Special Issue Assessments and Advances in Bone Regeneration, Therapies and Healing)

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14 pages, 2680 KiB

Open AccessArticle

In-Line Monitoring of Polyhydroxyalkanoate (PHA) Production during High-Cell-Density Plant Oil Cultivations Using Photon Density Wave Spectroscopy

by Björn Gutschmann, Thomas Schiewe, Manon T.H. Weiske, Peter Neubauer, Roland Hass and Sebastian L. Riedel

Bioengineering 2019, 6(3), 85; https://doi.org/10.3390/bioengineering6030085 - 19 Sep 2019

Cited by 29 | Viewed by 10111

Abstract

Polyhydroxyalkanoates (PHAs) are biodegradable plastic-like materials with versatile properties. Plant oils are excellent carbon sources for a cost-effective PHA production, due to their high carbon content, large availability, and comparatively low prices. Additionally, efficient process development and control is required for competitive PHA [...] Read more.

Polyhydroxyalkanoates (PHAs) are biodegradable plastic-like materials with versatile properties. Plant oils are excellent carbon sources for a cost-effective PHA production, due to their high carbon content, large availability, and comparatively low prices. Additionally, efficient process development and control is required for competitive PHA production, which can be facilitated by on-line or in-line monitoring devices. To this end, we have evaluated photon density wave (PDW) spectroscopy as a new process analytical technology for Ralstonia eutropha (Cupriavidus necator) H16 plant oil cultivations producing polyhydroxybutyrate (PHB) as an intracellular polymer. PDW spectroscopy was used for in-line recording of the reduced scattering coefficient µ_s’ and the absorption coefficient µ_a at 638 nm. A correlation of µ_s’ with the cell dry weight (CDW) and µ_a with the residual cell dry weight (RCDW) was observed during growth, PHB accumulation, and PHB degradation phases in batch and pulse feed cultivations. The correlation was used to predict CDW, RCDW, and PHB formation in a high-cell-density fed-batch cultivation with a productivity of 1.65 g_PHB·L⁻¹·h⁻¹ and a final biomass of 106 g·L⁻¹ containing 73 wt% PHB. The new method applied in this study allows in-line monitoring of CDW, RCDW, and PHA formation. Full article

(This article belongs to the Special Issue Advances in Polyhydroxyalkanoate (PHA) Production, Volume 2)

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17 pages, 4151 KiB

Open AccessArticle

Polyhydroxybutyrate Production from Natural Gas in A Bubble Column Bioreactor: Simulation Using COMSOL

by Mohsen Moradi, Hamid Rashedi, Soheil Rezazadeh Mofradnia, Kianoush Khosravi-Darani, Reihaneh Ashouri and Fatemeh Yazdian

Bioengineering 2019, 6(3), 84; https://doi.org/10.3390/bioengineering6030084 - 16 Sep 2019

Cited by 13 | Viewed by 6867

Abstract

In this study, the simulation of microorganism ability for the production of poly-β-hydroxybutyrate (PHB) from natural gas (as a carbon source) was carried out. Based on the Taguchi algorithm, the optimum situations for PHB production from natural gas in the columnar bubble reactor [...] Read more.

In this study, the simulation of microorganism ability for the production of poly-β-hydroxybutyrate (PHB) from natural gas (as a carbon source) was carried out. Based on the Taguchi algorithm, the optimum situations for PHB production from natural gas in the columnar bubble reactor with 30 cm length and 1.5 cm diameter at a temperature of 32 °C was evaluated. So, the volume ratio of air to methane of 50:50 was calculated. The simulation was carried out by COMSOL software with two-dimensional symmetric mode. Mass transfer, momentum, density-time, and density-place were investigated. The maximum production of biomass concentration reached was 1.63 g/L, which shows a 10% difference in contrast to the number of experimental results. Furthermore, the consequence of inlet gas rate on concentration and gas hold up was investigated Andres the simulation results were confirmed to experimental results with less than 20% error. Full article

(This article belongs to the Special Issue Advances in Polyhydroxyalkanoate (PHA) Production, Volume 2)

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15 pages, 4928 KiB

Open AccessArticle

Finite Element Driven Design Domain Identification of a Beating Left Ventricular Simulator

by Utku Gulbulak and Atila Ertas

Bioengineering 2019, 6(3), 83; https://doi.org/10.3390/bioengineering6030083 - 13 Sep 2019

Cited by 5 | Viewed by 5888

Abstract

Almost ten percent of the American population have heart diseases. Since the number of available heart donors is not promising, left ventricular assist devices are implemented as bridge therapies. Development of the assist devices benefits from both in-vivo animal and in-vitro mock circulation [...] Read more.

Almost ten percent of the American population have heart diseases. Since the number of available heart donors is not promising, left ventricular assist devices are implemented as bridge therapies. Development of the assist devices benefits from both in-vivo animal and in-vitro mock circulation studies. Representation of the heart is a crucial part of the mock circulation setups. Recently, a beating left ventricular simulator with latex rubber and helically oriented McKibben actuators has been proposed. The simulator was able to mimic heart wall motion, however, flow rate was reported to be limited to 2 liters per minute. This study offers a finite element driven design domain identification to identify the combination of wall thickness, number of actuators, and the orientation angle that results in better deformation. A nonlinear finite element model of the simulator was developed and validated. Design domain was constructed with 150 finite element models, each with varying wall thickness and number of actuators with varying orientation angles. Results showed that the combination of 4 mm wall thickness and 8 actuators with 90 degrees orientation performed best in the design domain. Full article

(This article belongs to the Special Issue Implantable Medical Devices)

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14 pages, 2042 KiB

Open AccessReview

Recent Advances in the Use of Polyhydroyalkanoates in Biomedicine

by Alejandra Rodriguez-Contreras

Bioengineering 2019, 6(3), 82; https://doi.org/10.3390/bioengineering6030082 - 12 Sep 2019

Cited by 76 | Viewed by 8632

Abstract

Polyhydroxyalkanoates (PHAs), a family of natural biopolyesters, are widely used in many applications, especially in biomedicine. Since they are produced by a variety of microorganisms, they possess special properties that synthetic polyesters do not have. Their biocompatibility, biodegradability, and non-toxicity are the crucial [...] Read more.

Polyhydroxyalkanoates (PHAs), a family of natural biopolyesters, are widely used in many applications, especially in biomedicine. Since they are produced by a variety of microorganisms, they possess special properties that synthetic polyesters do not have. Their biocompatibility, biodegradability, and non-toxicity are the crucial properties that make these biologically produced thermoplastics and elastomers suitable for their applications as biomaterials. Bacterial or archaeal fermentation by the combination of different carbohydrates or by the addition of specific inductors allows the bioproduction of a great variety of members from the PHAs family with diverse material properties. Poly(3-hydroxybutyrate) (PHB) and its copolymers, such as poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHVB) or poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (PHB4HB), are the most frequently used PHAs in the field of biomedicine. PHAs have been used in implantology as sutures and valves, in tissue engineering as bone graft substitutes, cartilage, stents for nerve repair, and cardiovascular patches. Due to their good biodegradability in the body and their breakdown products being unhazardous, they have also been remarkably applied as drug carriers for delivery systems. As lately there has been considerable and growing interest in the use of PHAs as biomaterials and their application in the field of medicine, this review provides an insight into the most recent scientific studies and advances in PHAs exploitation in biomedicine. Full article

(This article belongs to the Special Issue Advances in Polyhydroxyalkanoate (PHA) Production, Volume 2)

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19 pages, 1594 KiB

Open AccessReview

New Perspectives in Liver Transplantation: From Regeneration to Bioengineering

by Debora Bizzaro, Francesco Paolo Russo and Patrizia Burra

Bioengineering 2019, 6(3), 81; https://doi.org/10.3390/bioengineering6030081 - 11 Sep 2019

Cited by 19 | Viewed by 8717

Abstract

Advanced liver diseases have very high morbidity and mortality due to associated complications, and liver transplantation represents the only current therapeutic option. However, due to worldwide donor shortages, new alternative approaches are mandatory for such patients. Regenerative medicine could be the more appropriate [...] Read more.

Advanced liver diseases have very high morbidity and mortality due to associated complications, and liver transplantation represents the only current therapeutic option. However, due to worldwide donor shortages, new alternative approaches are mandatory for such patients. Regenerative medicine could be the more appropriate answer to this need. Advances in knowledge of physiology of liver regeneration, stem cells, and 3D scaffolds for tissue engineering have accelerated the race towards efficient therapies for liver failure. In this review, we propose an update on liver regeneration, cell-based regenerative medicine and bioengineering alternatives to liver transplantation. Full article

(This article belongs to the Special Issue Bioengineering Liver Transplantation)

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14 pages, 1142 KiB

Open AccessArticle

Comparison of Dry Versus Wet Milling to Improve Bioethanol or Methane Recovery from Solid Anaerobic Digestate

by Florian Monlau, Cecilia Sambusiti and Abdellatif Barakat

Bioengineering 2019, 6(3), 80; https://doi.org/10.3390/bioengineering6030080 - 6 Sep 2019

Cited by 10 | Viewed by 6132

Abstract

Biogas plants for waste treatment valorization are presently experiencing rapid development, especially in the agricultural sector, where large amounts of digestate are being generated. In this study, we investigated the effect of vibro-ball milling (VBM) for 5 and 30 min at a frequency [...] Read more.

Biogas plants for waste treatment valorization are presently experiencing rapid development, especially in the agricultural sector, where large amounts of digestate are being generated. In this study, we investigated the effect of vibro-ball milling (VBM) for 5 and 30 min at a frequency of 20 s⁻¹ on the physicochemical composition and enzymatic hydrolysis (30 U g⁻¹ total solids (TS) of cellulase and endo-1,4-xylanase from Trichoderma longibrachiatum) of dry and wet solid separated digestates from an agricultural biogas plant. We found that VBM of dry solid digestate improved the physical parameters as both the particle size and the crystallinity index (from 27% to 75%) were reduced. By contrast, VBM of wet solid digestate had a minimal effect on the physicochemical parameters. The best results in terms of cellulose and hemicelluloses hydrolysis were noted for 30 min of VBM of dry solid digestate, with hydrolysis yields of 64% and 85% for hemicelluloses and cellulose, respectively. At the condition of 30 min of VBM, bioethanol and methane production on the dry solid separated digestate was investigated. Bioethanol fermentation by simultaneous saccharification and fermentation resulted in an ethanol yield of 98 g_eth kg⁻¹ TS (corresponding to 90% of the theoretical value) versus 19 g_eth kg⁻¹ TS for raw solid digestate. Finally, in terms of methane potential, VBM for 30 min lead to an increase of the methane potential of 31% compared to untreated solid digestate. Full article

(This article belongs to the Special Issue Current Advances in Anaerobic Digestion Technology)

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2 pages, 178 KiB

Open AccessEditorial

Extracellular Vesicles: From Biology to Biomedical Applications

by Esther Serrano-Pertierra and Maria Carmen Blanco-López

Bioengineering 2019, 6(3), 79; https://doi.org/10.3390/bioengineering6030079 - 6 Sep 2019

Cited by 2 | Viewed by 4716

Abstract

Legend says that Philippides ran to Athens to announce the victory against the Persians in the Battle of Marathon [...] Full article

(This article belongs to the Special Issue Extracellular Vesicles: From Biology to Biomedical Applications)

16 pages, 1935 KiB

Open AccessArticle

Surface Area to Volume Ratio of Electrospun Polydioxanone Templates Regulates the Adsorption of Soluble Proteins from Human Serum

by Allison E. Fetz, Cristina A. Fantaziu, Richard A. Smith, Marko Z. Radic and Gary L. Bowlin

Bioengineering 2019, 6(3), 78; https://doi.org/10.3390/bioengineering6030078 - 31 Aug 2019

Cited by 16 | Viewed by 6066

Abstract

Neutrophils, the first cells that interact with surface-adsorbed proteins on biomaterials, have been increasingly recognized as critical maestros in the foreign body response for guided tissue regeneration. Recent research has shown that small diameter (SD) fibers of electrospun tissue regeneration templates, which have [...] Read more.

Neutrophils, the first cells that interact with surface-adsorbed proteins on biomaterials, have been increasingly recognized as critical maestros in the foreign body response for guided tissue regeneration. Recent research has shown that small diameter (SD) fibers of electrospun tissue regeneration templates, which have a high surface area to volume ratio (SAVR), enhance the release of neutrophil extracellular traps (NETs) compared to large diameter (LD) fibers, resulting in impaired tissue regeneration. In this study, we evaluated the adsorption of eight human serum proteins on the surface of electrospun templates to investigate how protein adsorption may regulate the release of NETs. Electrospun polydioxanone templates made from SD fibers with high SAVR and LD fibers with low SAVR, were incubated with 0.2% human serum and in situ protein adsorption was quantified with infrared-based immunodetection. Of the detected proteins, IgM and vitronectin adsorbed at low levels, suggesting that they do not play a central role in the release of NETs. Contrastingly, albumin and IgG adsorbed rapidly to the surface of the templates. One-hundred to 200 times more IgG adsorbed on the templates compared to albumin, with significantly greater adsorption occurring on the SD templates with high SAVR. Given that neutrophils express receptors that interact with IgG during phagocytosis and NET release, these results suggest that SAVR-dependent adsorption of IgG on the SD electrospun templates may contribute to the up-regulated release of NETs. Overall, this study may aid in the design of immunomodulatory biomaterials that regulate NET release and thus the potential for neutrophil-driven tissue regeneration. Full article

(This article belongs to the Special Issue Designing Tissue Scaffolds with Electrospun Fibers)

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11 pages, 2391 KiB

Open AccessArticle

Impact of Contact Constraints on the Dynamics of Idealized Intracranial Saccular Aneurysms

by Manjurul Alam and Padmanabhan Seshaiyer

Bioengineering 2019, 6(3), 77; https://doi.org/10.3390/bioengineering6030077 - 30 Aug 2019

Cited by 3 | Viewed by 6374

Abstract

The rupture potential of intracranial aneurysms is an important medical question for physicians. While most intracranial (brain) aneurysms are asymptomatic, the quantification of rupture potential of both symptomatic and asymptomatic lesions is an active area of research. Furthermore, an intracranial aneurysm constrained by [...] Read more.

The rupture potential of intracranial aneurysms is an important medical question for physicians. While most intracranial (brain) aneurysms are asymptomatic, the quantification of rupture potential of both symptomatic and asymptomatic lesions is an active area of research. Furthermore, an intracranial aneurysm constrained by an optic nerve tissue might be a scenario for a physician to deal with during the treatment process. In this work, we developed a computational model of an idealized intracranial saccular aneurysm constrained by a rigid nerve tissue to investigate the impact of constrained nerve tissues on the dynamics of aneurysms. A comparative parametric study for constraints of varying length on aneurysm surface was considered. Our computational results demonstrated the impact of contact constraints on the level of stress near the fundus and provided insight on when these constraints can be protective and when they can be destructive. The results show that lesions with long contact constraints generated higher stress (0.116 MPa), whereas lesions without constraints generated less stress (0.1 MPa) at the fundus, which indicated that lesions with nerve constraints can be protective and less likely to rupture than the lesions without constraints. Moreover, lesions with point load on the fundus generated the highest stress (18.15 MPa) and, hence, they can be destructive. Full article

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16 pages, 3832 KiB

Open AccessArticle

Gelatin-Methacryloyl (GelMA) Formulated with Human Platelet Lysate Supports Mesenchymal Stem Cell Proliferation and Differentiation and Enhances the Hydrogel’s Mechanical Properties

by Marline Kirsch, Luise Birnstein, Iliyana Pepelanova, Wiebke Handke, Jessica Rach, Axel Seltsam, Thomas Scheper and Antonina Lavrentieva

Bioengineering 2019, 6(3), 76; https://doi.org/10.3390/bioengineering6030076 - 28 Aug 2019

Cited by 40 | Viewed by 9471

Abstract

Three-dimensional (3D) cell culture is a major focus of current research, since cultivation under physiological conditions provides more reliable information about in vivo cell behavior. 3D cell cultures are used in basic research to better understand intercellular and cell-matrix interactions. Moreover, 3D cell [...] Read more.

Three-dimensional (3D) cell culture is a major focus of current research, since cultivation under physiological conditions provides more reliable information about in vivo cell behavior. 3D cell cultures are used in basic research to better understand intercellular and cell-matrix interactions. Moreover, 3D cell culture plays an increasingly important role in the in vitro testing of bioactive substances and tissue engineering. Gelatin-methacryloyl (GelMA) hydrogels of different degrees of functionalization (DoFs) are a versatile tool for 3D cell culture and related applications such as bioprinting. Human platelet lysate (hPL) has already demonstrated positive effects on 2D cell cultures of different cell types and has proven a valuable alternative to fetal calf serum (FCS). Traditionally, all hydrogels are formulated using buffers. In this study, we supplemented GelMA hydrogels of different DoF with hPL during adipose tissue-derived mesenchymal stem cell (AD-MSCs) encapsulation. We studied the effect of hPL supplementation on the spreading, proliferation, and osteogenic differentiation of AD-MSCs. In addition, the influence of hPL on hydrogel properties was also investigated. We demonstrate that the addition of hPL enhanced AD-MSC spreading, proliferation, and osteogenic differentiation in a concentration-dependent manner. Moreover, the addition of hPL also increased GelMA viscosity and stiffness. Full article

(This article belongs to the Special Issue Mesenchymal Stem Cells in Tissue Regeneration)

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18 pages, 3194 KiB

Open AccessReview

Advances in Magnetic Noble Metal/Iron-Based Oxide Hybrid Nanoparticles as Biomedical Devices

by Laura M. Sanchez and Vera A. Alvarez

Bioengineering 2019, 6(3), 75; https://doi.org/10.3390/bioengineering6030075 - 28 Aug 2019

Cited by 28 | Viewed by 6732

Abstract

The study of the noble metal magnetic hybrid nanoparticles is a really promising topic from both the scientific and the technological points of views, with applications in several fields. Iron oxide materials which are hybridized with noble metal nanoparticles (NPs) have attracted increasing [...] Read more.

The study of the noble metal magnetic hybrid nanoparticles is a really promising topic from both the scientific and the technological points of views, with applications in several fields. Iron oxide materials which are hybridized with noble metal nanoparticles (NPs) have attracted increasing interest among researchers because of their cooperative effects on combined magnetic, electronic, photonic, and catalytic activities. This review article contains a summary of magnetic noble metal/iron oxide nanoparticle systems potentially useful in practical biomedical applications. Among the applications, engineered devices for both medical diagnosis and treatments were considered. The preparation to produce different structures, as blends or core-shell structures, of several nanometric systems was also considered. Several characterization techniques available to describe the structure, morphology and different kinds of properties of hybrid nanoparticles are also included in this review. Full article

(This article belongs to the Special Issue Noble Metal Functionalized Nanoparticles for Biomedical Applications)

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10 pages, 597 KiB

Open AccessArticle

Biotechnological Production of Poly(3-Hydroxybutyrate-co-4-Hydroxybutyrate-co-3-Hydroxyvalerate) Terpolymer by Cupriavidus sp. DSM 19379

by Dan Kucera, Ivana Novackova, Iva Pernicova, Petr Sedlacek and Stanislav Obruca

Bioengineering 2019, 6(3), 74; https://doi.org/10.3390/bioengineering6030074 - 26 Aug 2019

Cited by 13 | Viewed by 6265

Abstract

The terpolymer of 3-hydroxybutyrate (3HB), 3-hydroxyvalerate (3HV), and 4-hydroxybutyrate (4HB) was produced employing Cupriavidus sp. DSM 19379. Growth in the presence of γ-butyrolactone, ε-caprolactone, 1,4-butanediol, and 1,6-hexanediol resulted in the synthesis of a polymer consisting of 3HB and 4HB monomers. Single and two-stage [...] Read more.

The terpolymer of 3-hydroxybutyrate (3HB), 3-hydroxyvalerate (3HV), and 4-hydroxybutyrate (4HB) was produced employing Cupriavidus sp. DSM 19379. Growth in the presence of γ-butyrolactone, ε-caprolactone, 1,4-butanediol, and 1,6-hexanediol resulted in the synthesis of a polymer consisting of 3HB and 4HB monomers. Single and two-stage terpolymer production strategies were utilized to incorporate the 3HV subunit into the polymer structure. At the single-stage cultivation mode, γ-butyrolactone or 1,4-butanediol served as the primary substrate and propionic and valeric acid as the precursor of 3HV. In the two-stage production, glycerol was used in the growth phase, and precursors for the formation of the terpolymer in combination with the nitrogen limitation in the medium were used in the second phase. The aim of this work was to maximize the Polyhydroxyalkanoates (PHA) yields with a high proportion of 3HV and 4HB using different culture strategies. The obtained polymers contained 0–29 mol% of 3HV and 16–32 mol% of 4HB. Selected polymers were subjected to a material properties analysis such as differential scanning calorimetry (DSC), thermogravimetry, and size exclusion chromatography coupled with multi angle light scattering (SEC-MALS) for determination of the molecular weight. The number of polymers in the biomass, as well as the monomer composition of the polymer were determined by gas chromatography. Full article

(This article belongs to the Special Issue Advances in Polyhydroxyalkanoate (PHA) Production, Volume 2)

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19 pages, 23331 KiB

Open AccessArticle

Metastasis of Cancer Stem Cells Developed in the Microenvironment of Hepatocellular Carcinoma

by Said M. Afify, Ghmkin Hassan, Amira Osman, Anna Sanchez Calle, Hend M Nawara, Maram Hussein Zahra, Samah EL-Ghlban, Hager Mansour, Md Jahangir Alam, Hagar A Abu Quora, Juan Du, Akimasa Seno, Yoshiaki Iwasaki and Masaharu Seno

Bioengineering 2019, 6(3), 73; https://doi.org/10.3390/bioengineering6030073 - 23 Aug 2019

Cited by 22 | Viewed by 8188

Abstract

Metastasis develops when cancer cells spread from the primary site of a malignant tumor to the surrounding and distant tissues, and it is the most critical problem in cancer treatment. Our group developed cancer stem cells (CSCs) from induced pluripotent stem cells (iPSCs) [...] Read more.

Metastasis develops when cancer cells spread from the primary site of a malignant tumor to the surrounding and distant tissues, and it is the most critical problem in cancer treatment. Our group developed cancer stem cells (CSCs) from induced pluripotent stem cells (iPSCs) in the presence of a conditioned medium (CM) of cancer-derived cells. The CSCs were characterized by the formation of malignant tumors in vivo, followed by metastasis. In this study, CSCs converted from mouse iPSCs in the presence of CM from hepatocellular carcinoma (HCC) cell line Huh7 cells. These converted cells (miPS-Huh7cm cells) were established as the metastatic cells. The generated CSCs were injected into the liver or spleen of nude mice. Almost one month after transplantation, the tumors were excised, and the primary cultured cells derived from the malignant tumors and metastatic nodules were evaluated by stemness and metastatic markers to compare their differences. The miPS-Huh7cm cells exhibited metastatic potential, and efficiently formed malignant tumors with lung and/or liver lesions in vivo, whereas the injected miPS formed teratoma. The primary cultured cells derived from the malignant tumors and metastatic nodules sustained the expression of stemness markers, such as Nanog, Klf4 and c-Myc, and acquired cancer stem markers, such as CD90, CD44 and ALDH1. Simultaneously, the expression of metastatic markers, such as Slug, Twist1 and vimentin, in primary cells derived from the malignant tumors, was higher than in metastatic nodules. The CSCs derived from iPSCs, forming malignant tumors and displaying high metastasis, will provide a good animal model to study the mechanisms of metastasis. Full article

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3 pages, 173 KiB

Open AccessEditorial

Introduction to the Special Issue on Stem Cell and Biologic Scaffold Engineering

by Panagiotis Mallis, Catherine Stavropoulos-Giokas and Efstathios Michalopoulos

Bioengineering 2019, 6(3), 72; https://doi.org/10.3390/bioengineering6030072 - 21 Aug 2019

Cited by 2 | Viewed by 5053

Abstract

Tissue engineering and regenerative medicine is a rapidly evolving research field that effectively combines stem cells and biologic scaffolds in order to replace damaged tissues. Biologic scaffolds can be produced through the removal of resident cellular populations using several tissue engineering approaches, such [...] Read more.

Tissue engineering and regenerative medicine is a rapidly evolving research field that effectively combines stem cells and biologic scaffolds in order to replace damaged tissues. Biologic scaffolds can be produced through the removal of resident cellular populations using several tissue engineering approaches, such as the decellularization method. In addition, tissue engineering requires the interaction of biologic scaffolds with cellular populations. Stem cells are characterized by unlimited cell division, self-renewal, and differentiation potential, distinguishing themselves as a frontline source for the repopulation of decellularized matrices and scaffolds. However, parameters such as stem cell number, in vitro cultivation conditions, and specific growth media composition need further evaluation. The ultimate goal is the development of “artificial” tissues similar to native ones, which is achieved by properly combining stem cells and biologic scaffolds, thus bringing artificial tissues one step closer to personalized medicine. In this special issue of Bioengineering, we highlight the beneficial effects of stem cells and scaffolds in the emerging field of tissue engineering. The current issue includes articles regarding the use of stem cells in tissue engineering approaches and the proper production of biologically based scaffolds like nerve conduit, esophageal scaffold, and fibrin gel. Full article

(This article belongs to the Special Issue Stem Cell and Biologic Scaffold Engineering)

19 pages, 3300 KiB

Open AccessArticle

Multifactorial Modeling Reveals a Dominant Role of Wnt Signaling in Lineage Commitment of Human Pluripotent Stem Cells

by Tiago P. Dias, Tiago G. Fernandes, Maria Margarida Diogo and Joaquim M. S. Cabral

Bioengineering 2019, 6(3), 71; https://doi.org/10.3390/bioengineering6030071 - 15 Aug 2019

Cited by 6 | Viewed by 7580

Abstract

The human primed pluripotent state is maintained by a complex balance of several signaling pathways governing pluripotency maintenance and commitment. Here, we explore a multiparameter approach using a full factorial design and a simple well-defined culture system to assess individual and synergistic contributions [...] Read more.

The human primed pluripotent state is maintained by a complex balance of several signaling pathways governing pluripotency maintenance and commitment. Here, we explore a multiparameter approach using a full factorial design and a simple well-defined culture system to assess individual and synergistic contributions of Wnt, FGF and TGFβ signaling to pluripotency and lineage specification of human induced pluripotent stem cells (hiPSC). Hierarchical clustering and quadratic models highlighted a dominant effect of Wnt signaling over FGF and TGFβ signaling, drawing hiPSCs towards mesendoderm lineages. In addition, a synergistic effect between Wnt signaling and FGF was observed to have a negative contribution to pluripotency maintenance and a positive contribution to ectoderm and mesoderm commitment. Furthermore, FGF and TGFβ signaling only contributed significantly for negative ectoderm scores, suggesting that the effect of both factors for pluripotency maintenance resides in a balance of inhibitory signals instead of proactive stimulation of hiPSC pluripotency. Overall, our dry-signaling multiparameter modeling approach can contribute to elucidate individual and synergistic inputs, providing an additional degree of comprehension of the complex regulatory mechanisms of human pluripotency and commitment. Full article

(This article belongs to the Special Issue Stem Cell and Biologic Scaffold Engineering)

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8 pages, 652 KiB

Open AccessCommunication

Mechanical Response Changes in Porcine Tricuspid Valve Anterior Leaflet Under Osmotic-Induced Swelling

by Samuel D. Salinas, Margaret M. Clark and Rouzbeh Amini

Bioengineering 2019, 6(3), 70; https://doi.org/10.3390/bioengineering6030070 - 15 Aug 2019

Cited by 9 | Viewed by 6080

Abstract

Since many soft tissues function in an isotonic in-vivo environment, it is expected that physiological osmolarity will be maintained when conducting experiments on these tissues ex-vivo. In this study, we aimed to examine how not adhering to such a practice may alter the [...] Read more.

Since many soft tissues function in an isotonic in-vivo environment, it is expected that physiological osmolarity will be maintained when conducting experiments on these tissues ex-vivo. In this study, we aimed to examine how not adhering to such a practice may alter the mechanical response of the tricuspid valve (TV) anterior leaflet. Tissue specimens were immersed in deionized (DI) water prior to quantification of the stress–strain responses using an in-plane biaxial mechanical testing device. Following a two-hour immersion in DI water, the tissue thickness increased an average of 107.3% in the DI water group compared to only 6.8% in the control group, in which the tissue samples were submerged in an isotonic phosphate buffered saline solution for the same period of time. Tissue strains evaluated at 85 kPa revealed a significant reduction in the radial direction, from 34.8% to 20%, following immersion in DI water. However, no significant change was observed in the control group. Our study demonstrated the impact of a hypo-osmotic environment on the mechanical response of TV anterior leaflet. The imbalance in ions leads to water absorption in the valvular tissue that can alter its mechanical response. As such, in ex-vivo experiments for which the native mechanical response of the valves is important, using an isotonic buffer solution is essential. Full article

(This article belongs to the Special Issue Advances in Biological Tissue Biomechanics)

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16 pages, 1870 KiB

Open AccessArticle

Thermal and Physico-Mechanical Characterizations of Thromboresistant Polyurethane Films

by Aaron C. Wilson, Shih-Feng Chou, Roberto Lozano, Jonathan Y. Chen and Pierre F. Neuenschwander

Bioengineering 2019, 6(3), 69; https://doi.org/10.3390/bioengineering6030069 - 14 Aug 2019

Cited by 11 | Viewed by 6153

Abstract

Hemocompatibility remains a challenge for injectable and/or implantable medical devices, and thromboresistant coatings appear to be one of the most attractive methods to down-regulate the unwanted enzymatic reactions that promote the formation of blood clots. Among all polymeric materials, polyurethanes (PUs) are a [...] Read more.

Hemocompatibility remains a challenge for injectable and/or implantable medical devices, and thromboresistant coatings appear to be one of the most attractive methods to down-regulate the unwanted enzymatic reactions that promote the formation of blood clots. Among all polymeric materials, polyurethanes (PUs) are a class of biomaterials with excellent biocompatibility and bioinertness that are suitable for the use of thromboresistant coatings. In this work, we investigated the thermal and physico-mechanical behaviors of ester-based and ether-based PU films for potential uses in thromboresistant coatings. Our results show that poly(ester urethane) and poly(ether urethane) films exhibited characteristic peaks corresponding to their molecular configurations. Thermal characterizations suggest a two-step decomposition process for the poly(ether urethane) films. Physico-mechanical characterizations show that the surfaces of the PU films were hydrophobic with minimal weight changes in physiological conditions over 14 days. All PU films exhibited high tensile strength and large elongation to failure, attributed to their semi-crystalline structure. Finally, the in vitro clotting assays confirmed their thromboresistance with approximately 1000-fold increase in contact time with human blood plasma as compared to the glass control. Our work correlates the structure-property relationships of PU films with their excellent thromboresistant ability. Full article

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12 pages, 2295 KiB

Open AccessCommunication

Biomechanical Role and Motion Contribution of Ligaments and Bony Constraints in the Elbow Stability: A Preliminary Study

by Elisa Panero, Laura Gastaldi, Mara Terzini, Cristina Bignardi, Arman Sard and Stefano Pastorelli

Bioengineering 2019, 6(3), 68; https://doi.org/10.3390/bioengineering6030068 - 7 Aug 2019

Cited by 9 | Viewed by 6191

Abstract

In flexion–extension motion, the interaction of several ligaments and bones characterizes the elbow joint stability. The aim of this preliminary study was to quantify the relative motion of the ulna with respect to the humerus in two human upper limbs specimens and to [...] Read more.

In flexion–extension motion, the interaction of several ligaments and bones characterizes the elbow joint stability. The aim of this preliminary study was to quantify the relative motion of the ulna with respect to the humerus in two human upper limbs specimens and to investigate the constraints role for maintaining the elbow joint stability in different section conditions. Two clusters of four markers were fixed respectively to the ulna and humerus, and their trajectory was recorded by a motion capture system during functional orthopedic maneuver. Considering the posterior bundle of medial collateral complex (pMUCL) and the coronoid, two section sequences were executed. The orthopedic maneuver of compression, pronation and varus force was repeated at 30°, 60° and 90° flexion for the functional investigation of constraints. Ulna deflection was compared to a baseline elbow flexion condition. With respect to the intact elbow, the coronoid osteotomy influences the elbow stability at 90° (deflection = 11.49 ± 17.39 mm), while small differences occur at 30° and 60°, due to ligaments constraint. The contemporary pMUCL section and coronoid osteotomy causes elbow instability, with large deflection at 30° (deflection = 34.40 ± 9.10 mm), 60° (deflection = 45.41 ± 18.47 mm) and 90° (deflection = 52.16 ± 21.92 mm). Surgeons may consider the pMUCL reconstruction in case of unfixable coronoid fracture. Full article

(This article belongs to the Special Issue Assessments and Advances in Bone Regeneration, Therapies and Healing)

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20 pages, 2981 KiB

Open AccessArticle

Impact of Four Protein Additives in Cryogels on Osteogenic Differentiation of Adipose-Derived Mesenchymal Stem Cells

by Victor Häussling, Sebastian Deninger, Laura Vidoni, Helen Rinderknecht, Marc Ruoß, Christian Arnscheidt, Kiriaki Athanasopulu, Ralf Kemkemer, Andreas K. Nussler and Sabrina Ehnert

Bioengineering 2019, 6(3), 67; https://doi.org/10.3390/bioengineering6030067 - 7 Aug 2019

Cited by 12 | Viewed by 6551

Abstract

Human adipose-derived mesenchymal stem/stromal cells (Ad-MSCs) have great potential for bone tissue engineering. Cryogels, mimicking the three-dimensional structure of spongy bone, represent ideal carriers for these cells. We developed poly(2-hydroxyethyl methacrylate) cryogels, containing hydroxyapatite to mimic inorganic bone matrix. Cryogels were additionally supplemented [...] Read more.

Human adipose-derived mesenchymal stem/stromal cells (Ad-MSCs) have great potential for bone tissue engineering. Cryogels, mimicking the three-dimensional structure of spongy bone, represent ideal carriers for these cells. We developed poly(2-hydroxyethyl methacrylate) cryogels, containing hydroxyapatite to mimic inorganic bone matrix. Cryogels were additionally supplemented with different types of proteins, namely collagen (Coll), platelet-rich plasma (PRP), immune cells-conditioned medium (CM), and RGD peptides (RGD). The different protein components did not affect scaffolds’ porosity or water-uptake capacity, but altered pore size and stiffness. Stiffness was highest in scaffolds with PRP (82.3 kPa), followed by Coll (55.3 kPa), CM (45.6 kPa), and RGD (32.8 kPa). Scaffolds with PRP, CM, and Coll had the largest pore diameters (~60 µm). Ad-MSCs were osteogenically differentiated on these scaffolds for 14 days. Cell attachment and survival rates were comparable for all four scaffolds. Runx2 and osteocalcin levels only increased in Ad-MSCs on Coll, PRP and CM cryogels. Osterix levels increased slightly in Ad-MSCs differentiated on Coll and PRP cryogels. With differentiation alkaline phosphatase activity decreased under all four conditions. In summary, besides Coll cryogel our PRP cryogel constitutes as an especially suitable carrier for bone tissue engineering. This is of special interest, as this scaffold can be generated with patients’ PRP. Full article

(This article belongs to the Special Issue Mesenchymal Stem Cells in Tissue Regeneration)

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14 pages, 1476 KiB

Open AccessTechnical Note

Short Term Results of Fibrin Gel Obtained from Cord Blood Units: A Preliminary in Vitro Study

by Panagiotis Mallis, Ioanna Gontika, Zetta Dimou, Effrosyni Panagouli, Jerome Zoidakis, Manousos Makridakis, Antonia Vlahou, Eleni Georgiou, Vasiliki Gkioka, Catherine Stavropoulos-Giokas and Efstathios Michalopoulos

Bioengineering 2019, 6(3), 66; https://doi.org/10.3390/bioengineering6030066 - 2 Aug 2019

Cited by 13 | Viewed by 7016

Abstract

Background: Recent findings have shown that the fibrin gel derived from cord blood units (CBUs) play a significant role in wound healing and tissue regeneration. The aim of this study was to standardize the fibrin gel production process in order to allow for [...] Read more.

Background: Recent findings have shown that the fibrin gel derived from cord blood units (CBUs) play a significant role in wound healing and tissue regeneration. The aim of this study was to standardize the fibrin gel production process in order to allow for its regular use. Methods: CBUs (n = 200) were assigned to 4 groups according to their initial volume. Then, a two-stage centrifugation protocol was applied in order to obtain platelet rich plasma (PRP). The concentration of platelets (PLTs), white blood cells (WBCs) and red blood cells (RBCs) were determined prior to and after the production process. In addition, targeted proteomic analysis using multiple reaction monitoring was performed. Finally, an appropriate volume of calcium gluconate was used in PRP for the production of fibrin gel. Results: The results of this study showed that high volume CBUs were characterized by greater recovery rates, concentration and number of PLTs compared to the low volume CBUs. Proteomic analysis revealed the presence of key proteins for regenerative medicine. Fibrin gel was successfully produced from CBUs of all groups. Conclusion: In this study, low volume CBUs could be an alternative source for the production of fibrin gel, which can be used in multiple regenerative medicine approaches. Full article

(This article belongs to the Special Issue Stem Cell and Biologic Scaffold Engineering)

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10 pages, 2528 KiB

Open AccessCommunication

Nanocellulose-Based Inks—Effect of Alginate Content on the Water Absorption of 3D Printed Constructs

by Eduardo Espinosa, Daniel Filgueira, Alejandro Rodríguez and Gary Chinga-Carrasco

Bioengineering 2019, 6(3), 65; https://doi.org/10.3390/bioengineering6030065 - 30 Jul 2019

Cited by 43 | Viewed by 8408

Abstract

2,2,6,6-tetramethylpyperidine-1-oxyl (TEMPO) oxidized cellulose nanofibrils (CNF) were used as ink for three-dimensional (3D) printing of porous structures with potential as wound dressings. Alginate (10, 20, 30 and 40 wt%) was incorporated into the formulation to facilitate the ionic cross-linking with calcium chloride (CaCl [...] Read more.

2,2,6,6-tetramethylpyperidine-1-oxyl (TEMPO) oxidized cellulose nanofibrils (CNF) were used as ink for three-dimensional (3D) printing of porous structures with potential as wound dressings. Alginate (10, 20, 30 and 40 wt%) was incorporated into the formulation to facilitate the ionic cross-linking with calcium chloride (CaCl₂). The effect of two different concentrations of CaCl₂ (50 and 100 mM) was studied. The 3D printed hydrogels were freeze-dried to produce aerogels which were tested for water absorption. Scanning Electronic Microscopy (SEM) pictures demonstrated that the higher the concentration of the cross-linker the higher the definition of the printed tracks. CNF-based aerogels showed a remarkable water absorption capability. Although the incorporation of alginate and the cross-linking with CaCl₂ led to shrinkage of the 3D printed constructs, the approach yielded suitable porous structures for water and moisture absorption. It is concluded that the 3D printed biocomposite structures developed in this study have characteristics that are promising for wound dressings devices. Full article

(This article belongs to the Section Nanobiotechnology and Biofabrication)

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11 pages, 6574 KiB

Open AccessArticle

Extraction of Peak Velocity Profiles from Doppler Echocardiography Using Image Processing

by Amirtahà Taebi, Richard H. Sandler, Bahram Kakavand and Hansen A. Mansy

Bioengineering 2019, 6(3), 64; https://doi.org/10.3390/bioengineering6030064 - 26 Jul 2019

Cited by 4 | Viewed by 6148

Abstract

The objective of this study is to extract positive and negative peak velocity profiles from Doppler echocardiographic images. These profiles are currently estimated using tedious manual approaches. Profiles can be used to establish realistic boundary conditions for computational hemodynamic studies and to estimate [...] Read more.

The objective of this study is to extract positive and negative peak velocity profiles from Doppler echocardiographic images. These profiles are currently estimated using tedious manual approaches. Profiles can be used to establish realistic boundary conditions for computational hemodynamic studies and to estimate cardiac time intervals, which are of clinical utility. In the current study, digital image processing algorithms that rely on intensity calculations and two different thresholding methods were proposed and tested. Image intensity histograms were used to guide threshold choices, which were selected such that the resulting velocity profiles appropriately represent Doppler shift envelopes. The resulting peak velocity profiles contained artifacts in the form of sudden velocity changes and possible outliers. To reduce these artifacts, image smoothing using a moving average process was then implemented. Bland–Altman analysis suggested good agreement between the two thresholding methods. Artifacts decreased when image smoothing was performed. Results also suggested that one thresholding method tended to provide the lower limit (i.e., underestimate) of velocities, while the second tended to provide the velocity upper limit (i.e., overestimate). Combining estimates from both methods appeared to provide a smoother peak velocity profile estimate. The proposed automated approach may be useful for objective estimation of peak velocity profiles, which may be helpful for computational hemodynamic studies and may increase the efficiency of current clinical diagnostic tools. Full article

(This article belongs to the Special Issue Biosignal Processing)

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6 pages, 792 KiB

Open AccessArticle

WeReview: CRISPR Tools—Live Repository of Computational Tools for Assisting CRISPR/Cas Experiments

by Rafael Torres-Perez, Juan A. Garcia-Martin, Lluis Montoliu, Juan C. Oliveros and Florencio Pazos

Bioengineering 2019, 6(3), 63; https://doi.org/10.3390/bioengineering6030063 - 25 Jul 2019

Cited by 17 | Viewed by 8023

Abstract

Computational tools are essential in the process of designing a CRISPR/Cas experiment for the targeted modification of an organism’s genome. Among other functionalities, these tools facilitate the design of a guide-RNA (gRNA) for a given nuclease that maximizes its binding to the intended [...] Read more.

Computational tools are essential in the process of designing a CRISPR/Cas experiment for the targeted modification of an organism’s genome. Among other functionalities, these tools facilitate the design of a guide-RNA (gRNA) for a given nuclease that maximizes its binding to the intended genomic site, while avoiding binding to undesired sites with similar sequences in the genome of the organism of interest (off-targets). Due to the popularity of this methodology and the rapid pace at which it evolves and changes, new computational tools show up constantly. This rapid turnover, together with the intrinsic high death-rate of bioinformatics tools, mean that many of the published tools become unavailable at some point. Consequently, the traditional ways to inform the community about the landscape of available tools, i.e., reviews in the scientific literature, are not adequate for this fast-moving field. To overcome these limitations, we have developed “WeReview: CRISPR Tools,” a live, on-line, user-updatable repository of computational tools to assist researchers in designing CRISPR/Cas experiments. In its web site users can find an updated comprehensive list of tools and search for those fulfilling their specific needs, as well as proposing modifications to the data associated with the tools or the incorporation of new ones. Full article

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13 pages, 1040 KiB

Open AccessArticle

Forced Degradation Testing as Complementary Tool for Biosimilarity Assessment

by Yan Felix Karl Dyck, Daniel Rehm, Jan Felix Joseph, Karsten Winkler, Volker Sandig, Wolfgang Jabs and Maria Kristina Parr

Bioengineering 2019, 6(3), 62; https://doi.org/10.3390/bioengineering6030062 - 21 Jul 2019

Cited by 15 | Viewed by 8533

Abstract

Oxidation of monoclonal antibodies (mAbs) can impact their efficacy and may therefore represent critical quality attributes (CQA) that require evaluation. To complement classical CQA, bevacizumab and infliximab were subjected to oxidative stress by H₂O₂ for 24, 48, or 72 h [...] Read more.

Oxidation of monoclonal antibodies (mAbs) can impact their efficacy and may therefore represent critical quality attributes (CQA) that require evaluation. To complement classical CQA, bevacizumab and infliximab were subjected to oxidative stress by H₂O₂ for 24, 48, or 72 h to probe their oxidation susceptibility. For investigation, a middle-up approach was used utilizing liquid chromatography hyphenated with mass spectrometry (LC-QTOF-MS). In both mAbs, the Fc/2 subunit was completely oxidized. Additional oxidations were found in the light chain (LC) and in the Fd’ subunit of infliximab, but not in bevacizumab. By direct comparison of methionine positions, the oxidized residues in infliximab were assigned to M55 in LC and M18 in Fd’. The forced oxidation approach was further exploited for comparison of respective biosimilar products. Both for bevacizumab and infliximab, comparison of posttranslational modification profiles demonstrated high similarity of the unstressed reference product (RP) and the biosimilar (BS). However, for bevacizumab, comparison after forced oxidation revealed a higher susceptibility of the BS compared to the RP. It may thus be considered a useful tool for biopharmaceutical engineering, biosimilarity assessment, as well as for quality control of protein drugs. Full article

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23 pages, 3165 KiB

Open AccessArticle

The Statistical Optimisation of Recombinant β-glucosidase Production through a Two-Stage, Multi-Model, Design of Experiments Approach

by Albert Uhoraningoga, Gemma K. Kinsella, Jesus M. Frias, Gary T. Henehan and Barry J. Ryan

Bioengineering 2019, 6(3), 61; https://doi.org/10.3390/bioengineering6030061 - 18 Jul 2019

Cited by 4 | Viewed by 6482

Abstract

β-glucosidases are a class of enzyme that are widely distributed in the living world, with examples noted in plants, fungi, animals and bacteria. They offer both hydrolysis and synthesis capacity for a wide range of biotechnological processes. However, the availability of native, or [...] Read more.

β-glucosidases are a class of enzyme that are widely distributed in the living world, with examples noted in plants, fungi, animals and bacteria. They offer both hydrolysis and synthesis capacity for a wide range of biotechnological processes. However, the availability of native, or the production of recombinant β-glucosidases, is currently a bottleneck in the widespread industrial application of this enzyme. In this present work, the production of recombinant β-glucosidase from Streptomyces griseus was optimised using a Design of Experiments strategy, comprising a two-stage, multi-model design. Three screening models were comparatively employed: Fractional Factorial, Plackett-Burman and Definitive Screening Design. Four variables (temperature, incubation time, tryptone, and OD_{600 nm}) were experimentally identified as having statistically significant effects on the production of S.griseus recombinant β-glucosidase in E. coli BL21 (DE3). The four most influential variables were subsequently used to optimise recombinant β-glucosidase production, employing Central Composite Design under Response Surface Methodology. Optimal levels were identified as: OD_{600 nm}, 0.55; temperature, 26 °C; incubation time, 12 h; and tryptone, 15 g/L. This yielded a 2.62-fold increase in recombinant β-glucosidase production, in comparison to the pre-optimised process. Affinity chromatography resulted in homogeneous, purified β-glucosidase that was characterised in terms of pH stability, metal ion compatibility and kinetic rates for p-nitrophenyl-β-D-glucopyranoside (pNPG) and cellobiose catalysis. Full article

(This article belongs to the Special Issue Genetic and Process Engineering Tools for Next Generation Cell Factories)

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12 pages, 3131 KiB

Open AccessArticle

3D Printing High-Consistency Enzymatic Nanocellulose Obtained from a Soda-Ethanol-O₂ Pine Sawdust Pulp

by Heli Kangas, Fernando E. Felissia, Daniel Filgueira, Nanci V. Ehman, María E. Vallejos, Camila M. Imlauer, Panu Lahtinen, María C. Area and Gary Chinga-Carrasco

Bioengineering 2019, 6(3), 60; https://doi.org/10.3390/bioengineering6030060 - 16 Jul 2019

Cited by 13 | Viewed by 8025

Abstract

Soda-ethanol pulps, prepared from a forestry residue pine sawdust, were treated according to high-consistency enzymatic fibrillation technology to manufacture nanocellulose. The obtained nanocellulose was characterized and used as ink for three-dimensional (3D) printing of various structures. It was also tested for its moisture [...] Read more.

Soda-ethanol pulps, prepared from a forestry residue pine sawdust, were treated according to high-consistency enzymatic fibrillation technology to manufacture nanocellulose. The obtained nanocellulose was characterized and used as ink for three-dimensional (3D) printing of various structures. It was also tested for its moisture sorption capacity and cytotoxicity, as preliminary tests for evaluating its suitability for wound dressing and similar applications. During the high-consistency enzymatic treatment it was found that only the treatment of the O₂-delignified pine pulp resulted in fibrillation into nano-scale. For 3D printing trials, the material needed to be fluidized further. By 3D printing, it was possible to fabricate various structures from the high-consistency enzymatic nanocellulose. However, the water sorption capacity of the structures was lower than previously seen with porous nanocellulose structures, indicating that further optimization of the material is needed. The material was found not to be cytotoxic, thus showing potential as material, e.g., for wound dressings and for printing tissue models. Full article

(This article belongs to the Section Nanobiotechnology and Biofabrication)

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30 pages, 1134 KiB

Open AccessReview

Hydrogels for Liver Tissue Engineering

by Shicheng Ye, Jochem W.B. Boeter, Louis C. Penning, Bart Spee and Kerstin Schneeberger

Bioengineering 2019, 6(3), 59; https://doi.org/10.3390/bioengineering6030059 - 5 Jul 2019

Cited by 73 | Viewed by 15629

Abstract

Bioengineered livers are promising in vitro models for drug testing, toxicological studies, and as disease models, and might in the future be an alternative for donor organs to treat end-stage liver diseases. Liver tissue engineering (LTE) aims to construct liver models that are [...] Read more.

Bioengineered livers are promising in vitro models for drug testing, toxicological studies, and as disease models, and might in the future be an alternative for donor organs to treat end-stage liver diseases. Liver tissue engineering (LTE) aims to construct liver models that are physiologically relevant. To make bioengineered livers, the two most important ingredients are hepatic cells and supportive materials such as hydrogels. In the past decades, dozens of hydrogels have been developed to act as supportive materials, and some have been used for in vitro models and formed functional liver constructs. However, currently none of the used hydrogels are suitable for in vivo transplantation. Here, the histology of the human liver and its relationship with LTE is introduced. After that, significant characteristics of hydrogels are described focusing on LTE. Then, both natural and synthetic materials utilized in hydrogels for LTE are reviewed individually. Finally, a conclusion is drawn on a comparison of the different hydrogels and their characteristics and ideal hydrogels are proposed to promote LTE. Full article

(This article belongs to the Special Issue Bioengineering Liver Transplantation)

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18 pages, 2516 KiB

Open AccessArticle

Biomechanical Restoration Potential of Pentagalloyl Glucose after Arterial Extracellular Matrix Degeneration

by Sourav S. Patnaik, Senol Piskin, Narasimha Rao Pillalamarri, Gabriela Romero, G. Patricia Escobar, Eugene Sprague and Ender A. Finol

Bioengineering 2019, 6(3), 58; https://doi.org/10.3390/bioengineering6030058 - 3 Jul 2019

Cited by 13 | Viewed by 7686

Abstract

The objective of this study was to quantify pentagalloyl glucose (PGG) mediated biomechanical restoration of degenerated extracellular matrix (ECM). Planar biaxial tensile testing was performed for native (N), enzyme-treated (collagenase and elastase) (E), and PGG (P) treated porcine abdominal aorta specimens (n = [...] Read more.

The objective of this study was to quantify pentagalloyl glucose (PGG) mediated biomechanical restoration of degenerated extracellular matrix (ECM). Planar biaxial tensile testing was performed for native (N), enzyme-treated (collagenase and elastase) (E), and PGG (P) treated porcine abdominal aorta specimens (n = 6 per group). An Ogden material model was fitted to the stress–strain data and finite element computational analyses of simulated native aorta and aneurysmal abdominal aorta were performed. The maximum tensile stress of the N group was higher than that in both E and P groups for both circumferential (43.78 ± 14.18 kPa vs. 10.03 ± 2.68 kPa vs. 13.85 ± 3.02 kPa; p = 0.0226) and longitudinal directions (33.89 ± 8.98 kPa vs. 9.04 ± 2.68 kPa vs. 14.69 ± 5.88 kPa; p = 0.0441). Tensile moduli in the circumferential direction was found to be in descending order as N > P > E (195.6 ± 58.72 kPa > 81.8 ± 22.76 kPa > 46.51 ± 15.04 kPa; p = 0.0314), whereas no significant differences were found in the longitudinal direction (p = 0.1607). PGG binds to the hydrophobic core of arterial tissues and the crosslinking of ECM fibers is one of the possible explanations for the recovery of biomechanical properties observed in this study. PGG is a beneficial polyphenol that can be potentially translated to clinical practice for preventing rupture of the aneurysmal arterial wall. Full article

(This article belongs to the Special Issue Advances in Biological Tissue Biomechanics)

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13 pages, 3040 KiB

Open AccessArticle

Incorporation of Fibrin Matrix into Electrospun Membranes for Periodontal Wound Healing

by Choyi Wong, Suyog Yoganarasimha, Caroline Carrico and Parthasarathy Madurantakam

Bioengineering 2019, 6(3), 57; https://doi.org/10.3390/bioengineering6030057 - 30 Jun 2019

Cited by 11 | Viewed by 6216

Abstract

Guided tissue regeneration (GTR) aims to regenerate the lost attachment apparatus caused by periodontal disease through the use of a membrane. The goal of this study is to create and characterize a novel hybrid membrane that contains biologically active fibrin matrix within a [...] Read more.

Guided tissue regeneration (GTR) aims to regenerate the lost attachment apparatus caused by periodontal disease through the use of a membrane. The goal of this study is to create and characterize a novel hybrid membrane that contains biologically active fibrin matrix within a synthetic polycaprolactone (PCL) electrospun membrane. Three-dimensional fibrin matrices and fibrin-incorporated electrospun membrane were created from fresh frozen plasma by centrifugation in glass vials under three different conditions: 400 g for 12 min, 1450 g for 15 min and 3000 g for 60 min. Half the membranes were crosslinked with 1% genipin. Degradation against trypsin indicated biologic stability while uniaxial tensile testing characterized mechanical properties. Continuous data was analyzed by ANOVA to detect differences between groups (p = 0.05). Fibrin-incorporated electrospun membranes showed statistically significant increase in mechanical properties (elastic modulus, strain at break and energy to break) compared to fibrin matrices. While crosslinking had marginal effects on mechanical properties, it did significantly increase biologic stability against trypsin (p < 0.0001). Lastly, membranes generated at 400 g and 1450 g were superior in mechanical properties and biologic stability compared to those generated at 3000 g. Fibrin-incorporated, crosslinked electrospun PCL membranes generated at lower centrifugation forces offers a novel strategy to generate a potentially superior membrane for GTR procedures. Full article

(This article belongs to the Special Issue Designing Tissue Scaffolds with Electrospun Fibers)

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