Search Results (130)

Nickel (Ni) is a ubiquitous trace metal, yet its physiological dynamics and dose-dependent roles in skeletal biology remain unclear. Here we combined elemental mapping, cellular assays, multi-omics and mouse models to define how Ni availability modulates osteogenesis. Ni, together with Manganese (Mn), chromium (Cr) and copper (Cu), was readily detectable in serum from both mice and humans. In situ LA–ICP–MS further showed that Ni levels in embryonic calvaria rose significantly across stages and CaO exhibited a consistent upward trend, suggesting coordinated accumulation of Ni with cranial mineralization. In vitro, Ni exerted biphasic effects on bone marrow mesenchymal stromal cells (BMSCs): high-dose Ni (100 μM) suppressed proliferation, elevated ROS, and induced time-dependent upregulation of Hmox1 and Nos2, consistent with escalating oxidative/nitrosative stress. By contrast, low-dose Ni (0.1 μM) enhanced matrix mineralization, whereas this pro-mineralization effect was attenuated at higher concentrations. In vivo, both Ni deprivation and Ni overload impaired bone formation: a Ni-free diet caused trabecular rarefaction and reduced mineral apposition, while high Ni hindered bone development of mice, especially in the early-stage intake. Mechanistically, RNA-seq and Ni-NTA proteomics identified Ni-driven osteogenic transcriptional remodeling and increased Ni-binding proteins, prioritizing integrin-linked kinase (ILK) as a Ni-inducible binder. ILK was required for osteogenic differentiation, and low-dose Ni activated AKT–mTOR signaling in an ILK-dependent manner. Finally, low-dose Ni-pretreated collagen scaffolds enhanced calvarial defect repair. Together, these findings define a narrow physiological window in which Ni supports osteogenesis via ILK–AKT–mTOR, whereas both deficiency and excess disrupt skeletal accrual. Full article

Background: Stromal remodeling in the tumor microenvironment contributes to multiple myeloma (MM) progression and drug resistance, but the extracellular mediators that drive these changes remain incompletely defined. Extracellular enolase-1 (ENO1), including membrane-associated and secreted forms, has been implicated in tumor progression; however, its role in cancer-associated fibroblast (CAF)-associated stromal reprogramming in MM is unclear. Methods: The effects of extracellular ENO1 on stromal activation and tumor-supportive functions were examined in MM using MM–bone marrow stromal cell (BMSC) co-cultures, lactate production and viability assays, immunoblotting, cytokine analyses, and a subcutaneous xenograft model of bortezomib (BTZ)-resistant MM in male 6–7-week-old NOD.Cg-Prkdc^scid Il2rg^tm1Vst/Vst (NPG) mice. HuL001, an anti-ENO1 monoclonal antibody, was used to evaluate the therapeutic relevance of extracellular ENO1 targeting. Results: Extracellular ENO1 promoted fibroblast activation protein expression through plasmin-mediated transforming growth factor-β (TGF-β) activation and induced a CAF-associated stromal phenotype marked by enhanced glycolytic activity and increased secretion of tumor-promoting cytokines in MM-BMSC co-cultures. HuL001 suppressed these ENO1-driven effects. HuL001-pretreated stromal cells also exhibited reduced tumor-supportive activity in a BTZ-resistant MM xenograft model. In addition, HuL001 combined with lenalidomide overcame BTZ resistance in MM. Conclusions: Extracellular ENO1 drives CAF-associated stromal reprogramming in the MM microenvironment through the ENO1/plasminogen/plasmin/TGF-β axis. Therapeutic targeting of extracellular ENO1 with HuL001 may disrupt these tumor-supportive stromal activities and help overcome drug resistance in MM. Full article

Loss of myelinating oligodendrocytes and myelin impairs motor and cognitive functions. Transplantation of autologous oligodendrocyte precursors (OPCs) holds promise for treatment of such diseases, but a protocol to derive human OPCs from a safe, ethical and accessible cell source with the rapidity required to catch the therapeutic window remains to be found. Although we previously generated myelinating glia from rat bone marrow stromal cells (BMSCs), it remains unknown if clinically sourced human BMSCs (hBMSCs) share the same potential. Moreover, whether the multipotency of BMSCs results from diverse progenitors preexisting in the bone marrow or from a single multipotent progenitor population remains unaddressed. Single-cell RNA sequencing data revealed a CD90^hiEGFR⁺PDGFRA⁺ pre-OPC-like subpopulation within hBMSCs. With a small-molecule-based (virus-free and supporting-cell-free) two-step induction protocol designed to expand this pre-OPC population, we generated functional OPCs with high purity in eight days. These derived OPCs showed phenotypic transcriptomes and immunoprofiles. They were also capable of myelinating naked axons when transplanted into myelin-deficient shiverer mice. Results highlight how targeted enrichment and maturation of specific progenitor subpopulations within hBMSCs allows rapid induction of desired cell types. These results place hBMSCs as a robust source of OPCs, unlocking the possibility for cell transplantation therapy for myelin deficiency in the central nervous system. Full article

During aging, bone marrow stromal (a.k.a. mesenchymal stem) cells (BMSCs) shift their lineage commitment away from osteogenesis and towards adipogenesis, resulting in bone loss and marrow fat accumulation. We previously reported that during osteogenesis, BMSCs activate mitochondrial oxidative phosphorylation (OXPHOS) at least in part by downregulating cyclophilin D (CypD) expression and, consequently, mitochondrial permeability transition pore (MPTP) activity. We also reported that in contrast, during adipogenesis, BMSCs upregulate CypD and MPTP, activate glycolysis and inhibit OXPHOS. To further study the role of CypD in BMSC bioenergetics, adipogenesis and bone marrow fat accumulation, we used CypD loss-of-function (LOF) or gain-of-function (GOF) models in osteo-adipoprogenitors in vitro and in vivo. We found that CypD LOF and GOF are associated with impaired and enhanced BMSC adipogenesis, respectively, both in vitro and in ectopic bone grafts in vivo. In addition, bioenergetic profiling and metabolomic analyses show evidence of corresponding metabolic reprogramming in CypD LOF and GOF cells. In summary, our study demonstrates the role of CypD-regulated mitochondrial metabolism during BMSC adipogenesis, facilitating the understanding of stem cell fate determination and the molecular mechanism of age-related bone loss as well as bone marrow fat accumulation. Full article

Background: The extracellular matrix (ECM) plays a central role in the mechanical strength and functional integration of tissue-engineered matrix (TEM), particularly in cardiovascular and load-bearing applications. Mesenchymal stromal cells (MSCs) from different sources may vary in their ECM-forming potential. Methods: In this study, adipose-derived (hADMSC), bone marrow-derived (hBMSC), and umbilical cord-derived MSCs (hUCMSC) were compared with human dermal fibroblasts (HDFBs) as a reference. Cells were seeded onto polyglycolic acid (PGA)/poly-4-hydroxybutyrate (P4HB) scaffolds and cultured for 3 weeks under static or hydrodynamic conditions using orbital shaking. TEM development was assessed macroscopically, histologically (using H&E and Masson’s trichrome stains), and by polarized light microscopy (Picrosirius Red), alongside biochemical assays that quantified DNA, glycosaminoglycan (GAGs), and hydroxyproline (HYP). Results: Hydrodynamically stimulated culture consistently improved ECM deposition across all groups. TEMs exposed to hydrodynamic stimulation (hydrodynamic conditions) were thicker, more uniformly filled, and exhibited increased collagen deposition compared with static TEMs, which remained thinner and showed persistent scaffold remnants. Polarized light analysis demonstrated that dynamic loading promoted collagen maturation in all groups, as evidenced by an increased prevalence of thick, birefringent collagen fibers indicative of mature collagen. Biochemical analyses showed that HDFB-derived TEMs produced the highest total collagen and ECM content under both static and hydrodynamic conditions; however, these matrices remained comparatively thin and densely packed. In contrast, MSC-derived TEMs formed thicker and more spatially distributed ECM in response to hydrodynamic stimulation. Conclusion: Among the MSC sources, hUCDMSC-derived TEMs exhibited the most advanced collagen maturation and the most uniform collagen distribution under hydrodynamically stimulated culture, whereas hADMSC-derived TEMs showed the greatest matrix thickening and volumetric ECM expansion with intermediate collagen maturation. hBMSC-derived TEMs displayed clear responsiveness to hydrodynamic stimulation but remained limited in overall collagen deposition and fiber maturation. These findings underscore that both hydrodynamic stimulation and cell source are critical not only for maximizing ECM deposition, but also for ensuring physiologically relevant collagen maturation and matrix organization in grafts suitable for clinical translation. Full article

Background: Bone remodeling depends on the dynamic balance between osteoclast-mediated bone resorption and osteoblast-mediated bone formation. Follistatin-like 1 (FSTL1) has been reported as an osteoclast-secreted protein that inhibits osteoclast differentiation, but its direct effects on osteoblast differentiation remain unclear. This study aimed to determine whether FSTL1 regulates osteoblast differentiation and mesenchymal stem cell migration and characterizes its role in osteoclast-osteoblast cellular cross-talk under in vitro conditions. Methods: Bone marrow-derived macrophages (BMMs) and stromal cells (BMSCs) from mice were used to induce osteoclast and osteoblast differentiation, respectively. Chemotaxis was assessed by Transwell migration, and osteoblast differentiation was evaluated in BMSC and MC3T3-E1 cells using staining, qRT-PCR, Western blotting, and proliferation assays. Results: FSTL1 significantly suppressed osteoclast differentiation and resorptive activity, confirmed by TRAP staining and pit assay, respectively. Expression of osteoclast markers such as NFATc1, TRAP, and DC-STAMP was reduced under FSTL1 treatment. In BMSCs, FSTL1 did not affect proliferation but significantly enhanced chemotaxis. Moreover, FSTL1 promoted osteogenic differentiation and mineralization, as demonstrated by increased ALP activity and Alizarin Red S staining. In MC3T3-E1 pre-osteoblasts, FSTL1 increased cell proliferation and mineralization by MTS and Alizarin Red staining. Key osteogenic markers, including Runx2 and osteocalcin, were also upregulated. Conclusions: Osteoclast-derived FSTL1 significantly suppresses osteoclastogenesis and promotes mesenchymal cell chemotaxis and osteogenic differentiation, indicating a role in regulating osteoclast–osteoblast cellular interactions in vitro. Targeting FSTL1 signaling may represent a promising therapeutic strategy for osteoporosis and other disorders of impaired bone remodeling. Full article

Background/Objectives: Bone marrow adipose tissue (BMAT) serves multiple physiological roles but accumulates with age, compromising skeletal health. This expansion is largely driven by an adipogenic drift of bone marrow mesenchymal stromal cells (BMSCs), shifting attention toward stromal cell fate regulation as a target to preserve bone marrow homeostasis. Preventing adipogenic commitment may be as relevant as directly inducing osteogenesis for maintaining a bone-permissive marrow microenvironment. Here, we investigated whether olive leaf extract (OLE) and its purified secoiridoid components, oleacin (OC) and oleuropein aglycone (OA), modulate the adipogenic differentiation and proliferative capacity of human BMSCs. Methods: Human BMSCs were induced to undergo adipogenic differentiation and treated with OLE, OC, or OA. Intracellular lipid accumulation and the expression of key adipogenic regulators were assessed. Proliferative capacity was evaluated under both maintenance and adipogenic conditions. Results: Under adipogenic conditions, OLE markedly reduced intracellular lipid accumulation and induced a coordinated downregulation of PPARγ, PLIN1, FABP4, ADIPOQ, LEP and the adipogenesis-associated miR-422a. In contrast, OC and OA exerted more selective and specific effects on biomarkers, indicating the partial and complementary modulation of adipogenic programs. Notably, OLE also increased BMSC proliferation under both maintenance and adipogenic conditions, suggesting the preservation of a less committed stromal cell pool. Although the relative contribution of enhanced proliferation versus the direct inhibition of adipogenic pathways cannot be fully disentangled, the combined molecular and functional data support a dual action of OLE on stromal cell fate. Conclusions: OLE limits adipogenic commitment while maintaining stromal cell proliferative competence, processes that are critically involved in BMAT expansion and bone marrow dysfunction. OC and OA contribute to OLE bioactivity deserving further investigation, particularly in combination, as potential modulators of BMAT expansion. Full article

This study investigates the effect of three-dimensional (3D) bioprinted collagen (Col) scaffolds (2% w/v collagen) loaded with autologous bone marrow stromal cells (BMSCs) and enriched with bone morphogenetic protein-2 (BMP-2) and hydroxyapatite-based particles (HAPPs) on bone regeneration in calvarial defects in rabbits. Three implant formulations, Col-(BMP-2) (at a concentration of 80 ng/mL), Col-HAPP (1% w/v) and a mixture of the two—Col-(BMP-2)-HAPP (40 ng/mL final concentration and 0.5% HAPP), were compared with a control group C-Per containing only periosteum to assess the influence of material structure, biochemical signals and cell component on osteogenesis. Histological analysis and quantitative computed tomography (CT) imaging parameters (HU values and residual defect diameter) showed significant differences between the groups, highlighting the role of combined strategies for optimal bone repair. The control group demonstrated the weakest regeneration, expressed by minimal lamellar bone and the largest residual defect. Col-(BMP-2) stimulated moderate osteoinduction with active osteoblasts but without a fully organised lamellar structure. Col-HAΡΡ provided more advanced regeneration, with histologically observed thick osteoid lamellae, early calcification, and structured lamellar architecture, emphasising the osteoconductive role of HAΡΡs. The strongest regeneration was reported with Col-(BMP-2)-HAΡΡ, where the synergy between BMP-2, HAΡΡs and BMSCs resulted in formed osteons, well-developed cancellous bone and minimal residual defects. The established negative correlation between bone density and residual calvarial defects emphasises the relationship between mineralisation and the degree of defect filling. The new data presented demonstrate that the combination of the abovementioned structural, biochemical and cellular factors in 3D bioprinted scaffolds offers a promising strategy for osteoregeneration of complex bone defects. Full article

Despite extensive exploration of gelatin methacryloyl (GelMA)-based hydrogels for bone tissue engineering, their clinical translation is hindered by a critical trade-off: poor precursor stability leads to rapid sedimentation of bioactive fillers like hydroxyapatite (HAp), while formulations optimized for injectability often sacrifice mechanical integrity or handling precision. To overcome this challenge, we report a rheologically engineered, injectable composite hydrogel scaffold that integrates unmodified gelatin as a thermoresponsive viscosity modulator into a GelMA/HAp matrix. The incorporation of gelatin yields a stable, paste-like precursor at physiological temperature, which effectively prevents HAp sedimentation and enables precise, filamentous extrusion. Subsequent UV crosslinking locks the homogeneous structure in place, resulting in a mechanically robust scaffold with significantly enhanced compressive modulus. In vitro studies demonstrate that this biomimetic microenvironment not only supports high viability and proliferation of bone marrow stromal cells (BMSCs) but also potently enhances their osteogenic differentiation, as evidenced by upregulated alkaline phosphatase activity, Runx2 expression, and matrix mineralization. This simple, one-step strategy successfully reconciles injectability, structural fidelity, and bioactivity, offering a highly promising and clinically translatable platform for minimally invasive bone regeneration. Full article

Background/Objectives: Nonunion bone healing results from a critical size defect that fails to bridge a bone injury to produce bony union. Novel approaches are critical for refining therapy in clinically challenging bone injuries, but the complex and coordinated nature of fracture callus tissue development requires study outside of the simple closed murine fracture model. Methods: We have utilized a three-dimensional printing approach to develop a scaffold construct with layers designed to sequentially release small molecule therapy within the tissues of a murine endochondral segmental defect to augment different mechanisms of fracture repair during critical stages of nonunion bone healing. Initially, a sonic hedgehog (SHH) agonist is released from a fibrin layer to promote chondrogenesis. A prolyl-hydroxylase domain (PHD)2 inhibitor is subsequently released from a β-tricalcium phosphate (β-TCP) layer to promote hypoxia-inducible factor (HIF)-1α regulation of angiogenesis. This sequential approach to therapy delivery is assisted by the inclusion of bone marrow stromal cells (BMSCs) to increase the cell substrate available for the small molecule therapy. Results: Immunohistochemistry of fracture callus tissue revealed increased expression of PTCH1 and HIF1α, targets of hedgehog and hypoxia signaling pathways, respectively, in the SAG21k/IOX2-treated mice compared to vehicle control. MicroCT and histology analyses showed increased bone in the fracture callus of mice that received therapy compared to control vehicle scaffolds. Conclusions: While our findings establish feasibility for the use of BMSCs and small molecules in the fibrin gel/β-TCP scaffolds to promote new bone formation for segmental defect healing, further optimization of these approaches is required to develop a fracture callus capable of completing bony union in a large defect. Full article

Acute myeloid leukemia (AML) proliferation is significantly influenced by the interactions between leukemia blasts and the bone marrow (BM) microenvironment. Specifically, bone marrow mesenchymal stem cells (BMSCs) derived from AML patients (AML-MSCs) are known to support leukemia growth and facilitate disease progression. Studies have demonstrated that the transfer of mitochondria from MSCs to AML blasts not only aids in disease progression but also contributes to chemotherapy resistance. Furthermore, BM stromal cells can trigger a metabolic shift in malignant cells from mitochondrial respiration to glycolysis, which enhances both growth and chemo-resistance. This study focuses on identifying transcriptional and metabolic alterations in AML-MSCs to uncover potential targeted therapies for AML. We employed RNA sequencing and microarray analysis on MSCs cocultured with leukemic cells (MLL-AF9) and on MSCs isolated from both non-leukemic and MLL-AF9 leukemic mice. The Gene Set Enrichment Analysis (GSEA) indicated a significant downregulation of gene sets associated with oxidative phosphorylation and glycolysis in AML-MSCs. Furthermore, coculture of MSCs from wild-type mice (WT-MSCs) and a healthy donor individual (HD-MSCs) with AML cells demonstrated reduced oxidative phosphorylation and glycolysis. These metabolic changes were consistent in AML-MSCs derived from both leukemic mice and patients. Our results indicate that AML cells diminish the metabolic capacity of MSCs, specifically targeting oxidative phosphorylation and glycolysis. These findings suggest potential metabolic vulnerabilities that could be exploited to develop more effective therapeutic strategies for AML. Full article

Multiple myeloma (MM) is an incurable malignancy characterized by the proliferation of abnormal plasma cells within the bone marrow, followed by potential dissemination to extramedullary sites. The bone marrow barrier (BMB) plays a pivotal role in plasma cell homing and disease progression. Bone marrow endothelial cells (BMECs) and bone marrow stromal cells (BMSCs), through their interactions with MM cells, secrete adhesion molecules, angiogenic cytokines, anti-apoptotic factors, and growth-promoting signals that support MM cell survival and proliferation. This review examines the components of the BMB and the major pathways involved in MM pathogenesis. Targeting the interactions between MM cells and the BMB may offer novel therapeutic opportunities. Full article

Osteolforte, a compound with potential bone-regenerative properties, was investigated for its effects on human bone marrow stromal cells (hBMSCs). This study aimed to evaluate its impact on cell viability, osteogenic differentiation, and both gene and protein expression using a combination of assays, including CCK-8, Alizarin Red S staining, Quantitative Real-Time PCR (qRT-PCR), and Western blot analysis. The results demonstrated that Osteolforte significantly enhanced osteogenic differentiation in hBMSCs. Alizarin Red S staining revealed increased mineralization, indicating elevated calcium deposition. Gene expression analysis showed an upregulation of key osteogenic markers, including runt-related transcription factor-2 (RUNX-2), collagen type I (COL-1), and bone morphogenetic protein-2 (BMP-2), supporting the role of Osteolforte in promoting osteoblastic activity. In particular, the elevated expression of RUNX-2—a master transcription factor in osteoblast differentiation along with COL-1, a major bone matrix component, and BMP-2, a key bone morphogenetic protein—highlights the compound’s osteogenic potential. In conclusion, Osteolforte enhances early-stage osteogenesis and mineralization in hBMSCs and represents a promising candidate for bone regeneration. Full article

This study investigated the effects of local fibroblast growth factor (FGF)-2 application on periodontal healing in an osteoporotic model, both in vivo and in vitro. Wistar rats were divided into the ovariectomy (OVX) and Control groups. Periodontal defects were created 8 weeks post-OVX and treated with hydroxypropylcellulose (HPC) or FGF-2 + HPC. Healing was evaluated through micro-computed tomography and histological analyses at 2 and 4 weeks. In vitro, bone marrow mesenchymal stromal cells (BMSCs) were cultured with/without FGF-2 and assessed for cell morphology, viability/proliferation, and osteoblastic marker expression. Alkaline phosphatase (ALP) staining was also performed. FGF-2-treated defects in both groups showed significantly greater bone volume fraction, trabecular number, and thickness compared to HPC only. Histologically, FGF-2 enhanced new bone formation, with the greatest levels in the Control group. In vitro, OVX BMSCs showed reduced actin staining versus controls. FGF-2 increased cell viability/proliferation and protrusions in both groups while downregulating Alpl and Bglap expression levels and reducing ALP-positive cells. FGF-2 increased new bone formation in the OVX group, stimulated proliferation of OVX BMSCs, and modulated their differentiation. FGF-2 could enhance periodontal healing even under osteoporotic conditions, albeit to a lesser extent. Full article

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is one of the side effects of bisphosphonate (BP) administration. Despite some preventive measures having been suggested, a definitive and effective treatment strategy for BRONJ remains to be established. Recent evidence has indicated that BPs dramatically impair the function of orofacial bone marrow stromal cells (BMSCs), which may contribute to the development of osteonecrosis. Thus, we hypothesized that recovery-impaired function of BMSCs at lesion sites could be beneficial in treating BRONJ. N6-methyladenosine (m6A) modification is the most common epigenetic modification and has been demonstrated to play a vital role in the modulation of BMSCs’ function. We detected the role of m6A modification in regulating the function of orofacial BMSCs under BP stimulation, and found that BPs led to a reduction in the global m6A methylation level, SAM level, and METTL3 expression in BMSCs during the osteogenic differentiation period. Meanwhile, betaine, a methyl group donor, effectively reversed the BP-decreased global m6A methylation level and SAM level in BMSCs, as well as rescuing the differentiation ability of impaired BMSCs. In the last part, we built a BRONJ rat model and supplemented rats with betaine via drinking water. The results showed that betaine successfully attenuated bone lesions and promoted wound healing in BP-injected rats, thereby providing new insight into future clinical treatment for BRONJ. Full article