Search Results (87)

The development of inks with suitable rheological, physicochemical, mechanical, and biological properties is crucial for the successful fabrication of functional scaffolds via extrusion-based 3D printing. In this study, collagen/chitosan hydrogels with varying polymer ratios were developed and characterized to evaluate their printability and suitability for cartilage tissue engineering. Rheological analyses revealed that all samples exhibited shear-thinning behavior and solid-like viscoelasticity, with the formulation of an 80:20 COL/CHI ratio (20CHI) demonstrating optimal filament formation and dimensional stability. Physicochemical analyses confirmed the preservation of the collagen triple helix and the formation of hydrogen bonding between chitosan and collagen. 20CHI scaffolds showed swelling capacity and high cohesiveness. In vitro studies confirmed the cytocompatibility of the scaffolds with murine fibroblasts and the ability of the scaffolds to promote adhesion, proliferation, and extracellular matrix production of both chondrocytes and adipogenic mesenchymal stem cells (aMSCs). Quantification of sulfated glycosaminoglycan (sGAG) indicated sustained matrix deposition over 28 days, particularly by chondrocytes. These findings demonstrate that 20CHI hydrogel is a promising candidate for 3D printing of biomimetic scaffolds for cartilage regeneration. Full article

Collagen is the primary protein in the extracellular matrix of human cells and the body and is essential for cell structure and function. Here, for the first time, we report a method for producing recombinant triple-helical collagen type III (rhCOL3) in transgenic tobacco as a bioreactor. We constructed a pMDV-COL3A1 vector containing the human type III collagen gene COL3A1, as well as a pMDV-COL3A1:5E vector that coexpressed COL3A1 and the enzymes required for its posttranslational modification. These two vectors were used to transform tobacco genetically. The COL3A1 gene was successfully coexpressed in tobacco plants with four enzymes that promote its posttranslational modification. The transcriptional level of COL3A1 in the transgenic lines coexpressing posttranslational modification genes was greater than that in the transgenic lines expressing only COL3A1. The enzyme-modified recombinant collagen was subsequently purified from a COL3A1:5E transgenic line. Our experimental results demonstrated that the terminal propeptides of plant-derived rhCOL3 can be correctly cleaved through the enzymatic hydrolysis of procollagen by coexpressed procollagen C proteinase (PCP) and procollagen N proteinase (PNP). The plant-derived rhCOL3 was thermally stable because the purified peptide chains can form a triple helix structure. Experiments have shown that plant-derived rhCOL3 has biological activity. In this study, functional recombinant full-length mature type III collagen with a triple-helix structure was successfully expressed in tobacco, providing a foundational plant-made material for future applications of collagen in human skin and bone repair in regenerative medicine. Full article

Collagen, the most abundant structural protein in animals, is fundamental for tissue integrity and regeneration. Conventional mammalian sources face limitations related to sustainability, safety, and ethical concerns, underscoring the need for alternative biomaterials. Marine organisms, particularly jellyfish, offer a promising eco-friendly collagen source. In this study, collagen and collagen-derived peptides were extracted from the cnidarian Physalia physalis and biochemically characterized. Circular dichroism demonstrated partial loss of triple-helix structure, while SDS-PAGE revealed type I collagen related α-chains together with low-molecular-weight fragments. The hydrolyzed collagen fractions exhibited keratinocyte and fibroblast cytocompatibility and increased keratinocyte migration. Moreover, P. physalis-derived peptides modulated inflammatory cytokine release in lipopolysaccharide-stimulated macrophages reducing tumor necrosis factor (TNF)-α by 38% and increasing interleukin (IL)-10 by 29%. Based on these results, a stable bioactive serum formulation incorporating P. physalis collagen peptides was developed. Overall, this work demonstrates that bioactive peptides from P. physalis possess immunomodulatory and regenerative potential and represent a promising new marine resource for cosmetic applications. Full article

Eel (Anguilla) is an aquatic animal with high nutritional value and multiple health benefits for the human body. To fully utilize its processing by-products fish bone, this study optimized the enzymatic preparation process of using BP neural network and GA genetic algorithm, with collagen extraction yield as the key evaluation metric, and characterized the properties of the obtained collagen. The results demonstrated that the optimal extraction conditions for eel bone collagen were as follows: enzyme dosage of 2%, hydrolysis time of 2.65 h, solid-to-liquid ratio of 1:22, and ultrasonic pretreatment for 21 min at 250 W power, achieving an extraction yield of 57.6%. The main amino acids identified were glycine, glutamic acid, proline, and arginine. SDS-PAGE electrophoresis revealed that eel bone collagen exhibited structural characteristics of type I collagen. Raman spectroscopy and X-ray diffraction indicated an intact triple-helix structure with partial ordered features. The DSC and TGA results demonstrated good thermal stability, with a denaturation temperature of 106.73 °C. SEM imaging displayed a loose, porous fibrous network structure, while rheological analysis suggested potential biomedical material properties. The findings of this study provide fundamental data for the high-value utilization and development of eel bone resources. Full article

The processing of fishery products generates a substantial amount of by-products, which can be utilized to promote a circular economy. The objective of the present study was to extract and characterize native collagen and total lipid extract from the fish skin and bones of crevalle jack (Caranx hippos). Physicochemical, structural, and morphological properties were evaluated for collagens. Chemical composition and functional properties were evaluated for lipid extracts. Native type I collagens were obtained by acid extraction, yielding approximately 2.64–6.16% (d.b.). The elemental chemical analysis showed its purity. The stability of the triple helix of collagen was verified through characteristic bands in the FTIR and UV spectra, the peaks at 2θ, around 7.5° and 19.5° obtained by XRD, and the bands of SDS-PAGE. Collagens show isoelectric points of 4.94 (skin) and 4.90 (bone), thermal stabilities of 53.40 °C (skin) and 46.88 °C (bone), and the percentage surface porosities of 41.28 (skin) and 38.84 (bone), all of which demonstrate their potential as a raw material in the biomedical field. The total lipids obtained were extracted using the Soxhlet and Folch methods. The extracts show EPA (1.26–3.16%) and DHA (3.94–9.78%) contents, with inhibition percentages of 32.7% (ABTS), 19.6% (DPPH), and 70.83% (β-carotene). These results highlight the potential of total lipid extract for nutraceutical and food applications. Full article

CaMK4, a calcium/calmodulin-dependent protein kinase, is an important mediator of cellular signal transduction, yet its role in the regulation of skeletal muscle satellite cells (MuSCs) in goats has remained unclear. In this study, CaMK4 overexpression and knockdown models were established, and integrated transcriptomic and proteomic analyses were performed to systematically elucidate its regulatory network. CaMK4 overexpression altered key pathways associated with cell proliferation and muscle development, including cAMP, PI3K-Akt, and actin cytoskeleton regulation, while proteomic data highlighted calcium signaling and JAK-STAT pathways. Conversely, CaMK4 knockdown enhanced MuSC proliferation by upregulating cell cycle-related genes and proteins. Integrated analyses further identified that Galectin-9 (LGALS9), Collagen triple helix repeat containing-1 (CTHRC1), Hyaluronan Synthase 1 (HAS1), and L-Threonine Dehydrogenase (TDH) may serve as potential key nodes regulating cell cycle, apoptosis, and metabolic control. This suggests a regulatory role for CaMK4. Collectively, these findings provide a mechanistic framework for understanding CaMK4 function in ruminant muscle development and may offer insights for improving goat muscle growth, meat quality traits, and production efficiency. Full article

Type II collagen (Col2), a crucial structural protein in hyaline cartilage, is essential for cartilage integrity and facilitating injury repair. However, research on recombinant type II collagen still faces many challenges, such as structure and yield, which limit the application of recombinant Col2 in biomedical fields. In this study, we achieved high-yield expression of full-length human Col2 (rhCol2) in CHO cells. The physical and chemical properties of rhCol2 were very close to native Col2, including molecular weight, triple helix structure, thermal stability and self-assembly capacity. Functional assays of primary chondrocytes have demonstrated that rhCol2 can effectively promote chondrocyte proliferation and increase the expression levels of cartilage-specific genes (Col2a1, Aggrecan, and Sox-9). Moreover, a cartilage defect model was surgically created in SD rats demonstrated that rhCol2 significantly enhanced cartilage repair, and the severity of the defect was assessed through histological and micro-CT analyses. Human chondrocytes were utilized to compare the effects of different collagens and verified through a series of functional experiments. In conclusion, these findings indicate that rhCol2 is an effective biomaterial and is expected to promote the application of recombinant collagen in the field of cartilage repair. Full article

Collagen is a family of large, fibrous biomacromolecules common in animals, distinguished by unique molecular, structural, and functional properties. Despite the relatively low complexity of their sequences and the repetitive conformation of the triple helix, which is the defining feature of this family, unraveling sequence–stability and structure–function relationships in this group of proteins remains a challenging task. Considering the importance of the structural aspects in collagen chain recognition and selection, we reviewed our current knowledge of the heterotrimeric structures of non-collagenous (NC) regions that lack the triple helix sequence motif, Gly-X-Y, and are crucial for the correct folding of the functional states of these proteins. This study was conducted by simultaneously surveying the current literature, mining the structural database, and making predictions of the three-dimensional structure of these domains using highly reliable approaches based on machine learning techniques, such as AlphaFold. The combination of experimental structural data and predictive analyses offers some interesting clues about the structural features of heterotrimers formed by collagen NC regions. Structural studies carried out in the last decade show that for fibrillar collagens (types I, V, XI, and mixed V/XI), key factors include the formation of specific disulfide bridges and electrostatic interaction patterns. In the subgroup of collagens whose heterotrimers create supramolecular networks (types IV and VIII), available structural information provides a solid ground for the definition of the basis of the molecular and supramolecular organization. Very recent AlphaFold predictions and structural analyses of type VI collagen offer strong evidence of the specific domains in the NC region of the protein that are involved in chain selection and their staggering. Insightful crystallographic studies have also revealed some fundamental elements of the chain selection process in type IX collagen. Collectively, the data reported here indicate that, although some aspects (particularly the quantification of the relative contribution of the NC and triple helix regions to correct collagen folding) are yet to be fully understood, the available structural information provides a solid foundation for future studies aimed at precisely defining sequence–structure–function relationships in collagens. Full article

The by-products of Cavia porcellus (legs and head) were valorized for collagen extraction using ultrasound-assisted extraction (UAE). Process optimization was performed through response surface methodology (central composite design) considering amplitude, cycle, and time as factors. Samples were pretreated with NaOH and butyl alcohol, followed by acetic acid extraction under controlled sonication. The quadratic models for yield and hydroxyproline showed excellent fit (high R², R²adj, and R²pred) with no significant lack of fit. The optimal conditions were identified at 100% amplitude, cycle = 1, and 27.47 min, and these were validated experimentally, yielding 28.15 ± 0.19% collagen and 4.18 ± 0.12% hydroxyproline, values that closely matched predictions. The optimal extract exhibited a hydrodynamic diameter of 599.3 nm, a ζ-potential of −61.3 mV, and a polydispersity index of 0.33, indicating a highly stable colloidal dispersion with submicron fibrils. SEM micrographs confirmed fibrillar bundles consistent with the particle size distribution, while FTIR spectra showed characteristic amide bands indicative of triple-helix preservation. These results demonstrate that UAE of guinea pig by-products produces collagen with high structural integrity and colloidal stability, highlighting its potential for food and biomaterial applications. Full article

β-Hydroxy-β-methylbutyrate (HMB), a natural metabolite derived from the essential amino acid leucine, is primarily recognised for its anabolic and anti-catabolic effects on skeletal muscle tissue. Recent studies indicate that HMB may also play a role in influencing the structural organisation of extracellular matrix (ECM) components, particularly collagen, which is crucial for maintaining the mechanical integrity of connective tissues. In this investigation, bovine type I collagen was polymerised in the presence of two concentrations of HMB (0.025 M and 0.25 M) to explore its potential function as a molecular modulator of fibrillogenesis. The morphology of the resulting collagen fibres and their molecular architecture were examined using atomic force microscopy (AFM) and Fourier-transform infrared (FTIR) spectroscopy. The findings demonstrated that lower levels of HMB facilitated the formation of more regular and well-organised fibrillar structures, exhibiting increased D-band periodicity and enhanced stabilisation of the native collagen triple helix, as indicated by Amide I and III band profiles. Conversely, higher concentrations of HMB led to significant disruption of fibril morphology and alterations in secondary structure, suggesting that HMB interferes with the self-assembly of collagen monomers. These structural changes are consistent with a non-covalent influence on interchain interactions and fibril organisation, to which hydrogen bonding and short-range electrostatics may contribute. Collectively, the results highlight the potential of HMB as a small-molecule regulator for soft-tissue matrix engineering, extending its consideration beyond metabolic supplementation towards controllable, materials-oriented modulation of ECM structure. Full article

Fish-derived collagen can reduce the risk of disease transmission and has no religious or cultural restrictions. However, it has limited applications due to its poor thermal stability. In this study, black carp swim bladder collagen (BBC), classified as a type I collagen, was extracted. Amino acid composition analysis revealed that BBC had a higher proline hydroxylation rate of 39.57%. Fourier transform infrared spectroscopy revealed that BBC exhibited a complete triple-helix structure. The fractional viscosity curve and differential scanning calorimetry curves revealed that the thermal denaturation temperature (Td) and the melting temperature (Tm) were 30.85 °C and 107.19 °C, respectively. The dynamic rheological analysis showed that as the concentration increased from 5 mg/mL to 20 mg/mL at 0.01 Hz, the storage modulus increased from 0.979 Pa to 84.2 Pa. When the temperature exceeded the Td, the BBC solution exhibited viscous behaviour as the frequency increased. The steady-shear analysis showed that the BBC was a shear-thinning fluid. Functional properties analysis revealed that BBC exhibited better emulsification properties, foaming properties, water absorption capacity and oil absorption capacity than land-derived collagen, making it suitable for emulsifiers, bubbling beverages, and frozen meat preservation. Additionally, BBC promoted the growth of MT3C3-E1 cells and maintained the normal morphology of the cells. These results showed that BBC is a promising substitute for terrestrial collagen in functional foods, cosmetics, and biofunctional materials. Full article

Background: Despite increased attention to double-jointedness or joint hypermobility as seen in connective tissue dysplasias like Ehlers–Danlos syndrome, improved clinical DNA correlations are needed to reduce decadal delays in diagnosis. Methods: To this end, patterns of history (among 80) and physical (among 40) findings are compared for 121 Ehlers–Danlos syndrome patients with recurring variants in collagen type I, II, III, V, VI, VII, IX, XI, and XII genes and novel ones in type XV, XVII, XVIII, and XXVII. Results: A recognizable tissue laxity–dysautonomia profile that transcended collagen biochemical class, triple helix component, mutation type, or presence of accessory DNA variants was defined with a few exceptions. Patients with novel variations experienced severe symptoms at younger ages (6–10 versus 14–18 years) and those with collagen type III variations had more than one significant difference in finding frequencies (spinal disk issues 75% versus 49%; bloating-reflux 100% versus 69%; migraines or menorrhagia 92% versus 53%). Conclusions: These results suggest that collagen DNA variants of diverse gene and molecular type can demonstrate EDS disposition and hasten its diagnosis when distress and disease become manifest. Full article

Adipogenesis is regulated by the coordinated activity of adipogenic transcription factors including PPAR-gamma and C/EBP alpha, while dysregulated adipogenesis can predispose adipose tissues to adipocyte hypertrophy and hyperplasia. We have previously reported that Cthrc1-null mice have increased adiposity compared to wildtype mice, supporting the notion that CTHRC1 regulates body composition. Herein, we derived conditioned medium from 3T3-L1 cells expressing human CTHRC1 and investigated its anti-adipogenic activity. This constituent significantly reduced 3T3-L1 cell adipogenic differentiation commensurate to the marked suppression of Cebpa and Pparg gene expression. It also increased the expression of the anti-adipogenic transcription factor SOX9 and promoted its nuclear translocation. Importantly, Sox9 gene knockdown demonstrated that the anti-adipogenic effect produced by this conditioned medium is dependent on SOX9 expression, while its ability to positively regulate SOX9 was attenuated by the application of Rho and Rac1 signaling pathway inhibitors. We also identified the selective expression of CTHRC1 in PDGFRA-expressing cell populations in human white adipose tissue, but not brown or perivascular adipose tissues. Congruently, flow cytometry revealed CTHRC1 expression in PDGFR-alpha⁺ stromal cells of mouse white adipose tissue, thus defining a novel stromal cell population that could underpin the ability of CTHRC1 to regulate adiposity. Full article

The purpose of this study was to explore the water retention mechanism of chicken claws by detecting the structural changes in collagen in boneless chicken claws under different expansion rates. Firstly, boneless chicken claw collagen with different expansion rates (0%, 10%, 20%, 30%, 40%, 50%) was extracted by the acid–enzyme complex method, and the changes in collagen were determined by scanning electron microscopy (SEM), ultraviolet spectroscopy (UV), Fourier transform infrared spectroscopy (FTIR), circular dichroism (CD), low-field nuclear magnetic resonance LF-NMR) and surface hydrophobicity to explore the mechanism that leads to changes in the water retention performance. The results of scanning electron microscopy showed that with the increase in the expansion rate, collagen molecules showed curling, shrinking, breaking and crosslinking, forming a loose and irregular pore-like denatured collagen structure. UV analysis showed that the maximum absorption wavelength of chicken claw collagen was blue shifted under different expansion rates, and the maximum absorption peak intensity increased first and then decreased with the increase in expansion rate. The FTIR results showed that collagen had obvious characteristic absorption peaks in the amide A, B, I, II and III regions under different expansion rates, and that the intensity and position of the characteristic absorption peaks changed with the expansion rate. The results of the CD analysis showed that collagen at different expansion rates had obvious positive absorption peaks at 222 nm, and that the position of negative absorption peaks was red shifted with the increase in expansion rate. This shows that the expansion treatment makes the collagen of chicken claw partially denatured, and that the triple helix structure becomes relaxed or unwound, which provides more space for the combination of water molecules, thus enhancing the water absorption capacity of boneless chicken claw. The results of the surface hydrophobicity test showed that the surface hydrophobicity of boneless chicken claw collagen increased with the increase in expansion rate and reached the maximum at a 30% expansion rate, and then decreased with the further increase in the expansion rate. The results of LF-NMR showed that the water content of boneless chicken claws increased significantly after the expansion treatment, and that the water retention performance of chicken claws was further enhanced with the increase in the expansion rate. In this study, boneless chicken claws were used as raw materials, and the expansion process of boneless chicken claws was optimized by acid combined with a water-retaining agent, which improved the expansion rate of boneless chicken claws and the quality of boneless chicken claws. The effects of the swelling degree on the collagen structure, water absorption and water retention properties of boneless chicken claws were revealed by structural characterization. These findings explain the changes in the water retention of boneless chicken claws after expansion. By optimizing the expansion treatment process, the water retention performance and market added value of chicken feet products can be significantly improved, which is of great economic significance. Full article

Collagen possesses distinctive chemical properties and biological functions due to its unique triple helix structure. However, recombinant collagen expressed in Escherichia coli without post-translational modifications such as hydroxylation lacks full function since hydroxylation is considered to be critical to the stability of the collagen triple-helix at body temperature. Here, a proline-deficient E. coli strain was constructed and employed to prepare hydroxylated recombinant collagens by incorporating proline (Pro) and hydroxyproline (Hyp) from the culture medium. By controlling the ratio of Pro to Hyp in the culture medium, collagen with different degrees of hydroxylation (0–88%) can be obtained. When the ratio of Pro and Hyp was adjusted to 12:8 mM, the proline hydroxylation rate of recombinant human collagen (rhCol, 55 kDa) ranged from 40–50%, which was also the degree of natural collagen. After proline hydroxylation, both the thermal stability and cell binding of rhCol were significantly enhanced. Notably, when the hydroxylation rate approached that of native human collagen (40–50%), the improvements were most pronounced. Moreover, the cell binding of rhCol with a hydroxylation rate of 43% increased by 29%, and the melting temperature (Tm) rose by 5 °C compared to the non-hydroxylated rhCol. The system achieved a yield of 1.186 g/L of rhCol by batch-fed in a 7 L fermenter. This innovative technology is expected to drive the development and application of collagen-related biomaterials with significant application value in the fields of tissue engineering, regenerative medicine, and biopharmaceuticals. Full article