Mesenchymal stem cell-based therapy for osteoporotic bones: Effects of the interaction between cells from healthy and osteoporotic rats on osteoblast differentiation and bone repair

AIMS

Cell therapy utilizing mesenchymal stem cells (MSCs) from healthy donors (HE-MSCs) is a promising strategy for treating osteoporotic bone defects. This study investigated the effects of interaction between HE-MSCs and MSCs from osteoporotic donors (ORX-MSCs) on osteoblast differentiation of MSCs and of HE-MSCs on bone formation in calvarial defects of osteoporotic rats.

MATERIALS AND METHODS

Osteoporosis was induced by orchiectomy (ORX) and its effects on the bone were evaluated by femur microtomography (μCT) and osteoblast differentiation of bone marrow MSCs. HE- and ORX-MSCs were cocultured, and osteoblast differentiation was evaluated using genotypic and phenotypic parameters. HE-MSCs were injected into the calvarial defects of osteoporotic rats, and bone formation was evaluated by μCT, histology, and gene expression of osteoblast markers.

KEY FINDINGS

ORX-induced osteoporosis was revealed by reduced bone morphometric parameters and osteoblast differentiation in ORX-MSCs. HE-MSCs partially recovered the osteogenic potential of ORX-MSCs, whereas HE-MSCs were mildly affected by ORX-MSCs. Additionally, the bone morphogenetic protein and wingless-related integration site signaling pathway components were similarly modulated in cocultures involving ORX-MSCs. HE-MSCs induced meaningful bone formation, highlighting the effectiveness of cell therapy even in osteoporotic bones.

SIGNIFICANCE

These results provide new perspectives on the development of cell-based therapies to regenerate bone defects in patients with disorders that affect bone tissue.

Mesenchymal Stem Cells Combined with a P(VDF-TrFE)/BaTiO3 Scaffold and Photobiomodulation Therapy Enhance Bone Repair in Rat Calvarial Defects

BACKGROUND

Tissue engineering and cell therapy have been the focus of investigations on how to treat challenging bone defects. This study aimed to produce and characterize a P(VDF-TrFE)/BaTiO₃ scaffold and evaluate the effect of mesenchymal stem cells (MSCs) combined with this scaffold and photobiomodulation (PBM) on bone repair.

METHODS AND RESULTS

P(VDF-TrFE)/BaTiO₃ was synthesized using an electrospinning technique and presented physical and chemical properties suitable for bone tissue engineering. This scaffold was implanted in rat calvarial defects (unilateral, 5 mm in diameter) and, 2 weeks post-implantation, MSCs were locally injected into these defects (n = 12/group). Photobiomodulation was then applied immediately, and again 48 and 96 h post-injection. The μCT and histological analyses showed an increment in bone formation, which exhibited a positive correlation with the treatments combined with the scaffold, with MSCs and PBM inducing more bone repair, followed by the scaffold combined with PBM, the scaffold combined with MSCs, and finally the scaffold alone (ANOVA, p ≤ 0.05).

CONCLUSIONS

The P(VDF-TrFE)/BaTiO₃ scaffold acted synergistically with MSCs and PBM to induce bone repair in rat calvarial defects. These findings emphasize the need to combine a range of techniques to regenerate large bone defects and provide avenues for further investigations on innovative tissue engineering approaches.

Collagen/κ-Carrageenan-Based Scaffolds as Biomimetic Constructs for In Vitro Bone Mineralization Studies

Tissue engineering offers attractive strategies to develop three-dimensional scaffolds mimicking the complex hierarchical structure of the native bone. The bone is formed by cells incorporated in a molecularly organized extracellular matrix made of an inorganic phase, called biological apatite, and an organic phase mainly made of collagen and noncollagenous macromolecules. Although many strategies have been developed to replicate the complexity of bone at the nanoscale in vitro, a critical challenge has been to control the orchestrated process of mineralization promoted by bone cells in vivo and replicate the anatomical and biological properties of native bone. In this study, we used type I collagen to fabricate mineralized scaffolds mimicking the microenvironment of the native bone. The sulfated polysaccharide κ-carrageenan was added to the scaffolds to fulfill the role of noncollagenous macromolecules in the organization and mineralization of the bone matrix and cell adhesion. Scanning electron microscopy images of the surface of the collagen/κ-carrageenan scaffolds showed the presence of a dense and uniform network of intertwined fibrils, while images of the scaffolds' lateral sides showed the presence of collagen fibrils with a parallel alignment, which is characteristic of dense connective tissues. MC3T3-E1 osteoblasts were cultured in the collagen scaffolds and were viable after up to 7 days of culture, both in the absence and in the presence of κ-carrageenan. The presence of κ-carrageenan in the collagen scaffolds stimulated the maturation of the cells to a mineralizing phenotype, as suggested by the increased expression of key genes related to bone mineralization, including alkaline phosphatase (Alp), bone sialoprotein (Bsp), osteocalcin (Oc), and osteopontin (Opn), as well as the ability to mineralize the extracellular matrix after 14 and 21 days of culture. Taken together, the results described in this study shed light on the potential use of collagen/κ-carrageenan scaffolds to study the role of the structural organization of bone-mimetic synthetic matrices in cell function.

Human periodontal ligament stem cells with distinct osteogenic potential induce bone formation in rat calvaria defects

Aim: This study aimed to evaluate the ability of human periodontal ligament stem cells (PDLSCs) with high (HP-PDLSCs) and low (LP-PDLSCs) osteogenic potential, in addition to mixed cells, to repair bone tissue. Methods: Cell phenotype, proliferation and differentiation were evaluated. Undifferentiated PDLSCs were injected into rat calvarial defects and the new bone was evaluated by μCT, histology and real-time PCR. Results: PDLSCs exhibited a typical mesenchymal stem cell phenotype and HP-PDLSCs showed lower proliferative and higher osteogenic potential than LP-PDLSCs. PDLSCs induced similar bone formation and histological analysis suggests a remodeling process, confirmed by osteogenic and osteoclastogenic markers, especially in tissues derived from defects treated with HP-PDLSCs. Conclusion: PDLSCs induced similar bone formation irrespective of their in vitro osteogenic potential.

The extracellular matrix protein Agrin is expressed by osteoblasts and contributes to their differentiation

The extracellular matrix protein Agrin has been detected in chondrocytes and endosteal osteoblasts but its function in osteoblast differentiation has not been investigated yet. Thus, it is possible that Agrin contributes to osteoblast differentiation and, due to Agrin and wingless-related integration site (Wnt) sharing the same receptor, transmembrane low-density lipoprotein receptor-related protein 4 (Lrp4), and the crosstalk between Wnt and bone morphogenetic protein (BMP) signalling, both pathways could be involved in this Agrin-mediated osteoblast differentiation. Confirming this, Agrin and its receptors Lrp4 and α-dystroglycan (Dag1) were expressed during differentiation of osteoblasts from three different sources. Moreover, the disruption of Agrin impaired the expression of its receptors and osteoblast differentiation, and the treatment with recombinant Agrin slightly increase this process. In addition, whilst Agrin knockdown downregulated the expression of genes related to Wnt and BMP signalling pathways, the addition of Agrin had no effect on these genes. Altogether, these data uncover the contribution of Agrin to osteoblast differentiation and suggest that, at least in part, an Agrin-Wnt-BMP circuit is involved in this process. This makes Agrin a candidate as target for developing new therapeutic strategies to treat bone-related diseases and injuries.

Jabuticaba peel extract modulates adipocyte and osteoblast differentiation of MSCs from healthy and osteoporotic rats

INTRODUCTION

The jabuticaba peel extract (JPE) contains bioactive compounds that regulate fat metabolism. Because the negative correlation between fat accumulation and bone formation in bone marrow, we hypothesized that JPE inhibits adipocyte as well as favors osteoblast differentiation of mesenchymal stromal cells (MSCs) under healthy and osteoporotic conditions, a disease that display an imbalance between adipocyte and osteoblast differentiation resulting in reduced bone mass.

MATERIAL AND METHODS

To test these hypotheses, bone marrow MSCs were harvested from healthy and osteoporotic rats and cultured in adipogenic and osteogenic media with three concentrations of JPE, 0.25, 5 and 10 µg/ml, and vehicle (control). After selecting the most efficient concentrations of JPE, we used them to evaluate adipocyte and osteoblast differentiation of MSCs from both sources.

RESULTS

We observed that, in general, JPE inhibited adipocyte differentiation of MSCs with more pronounced effects in cells from healthy than osteoporotic rats. In addition, JPE increased osteoblast differentiation, exhibiting a slightly higher osteogenic potential on MSCs from osteoporotic compared to healthy condition.

CONCLUSION

Our results demonstrated that JPE drives MSCs to inhibit adipocyte differentiation and toward osteoblast differentiation under healthy and osteoporotic conditions. These findings pave the way for further translational studies to investigate the therapeutic possibilities of JPE in both prevention and treatment of osteoporosis.

Recovering the osteoblastic differentiation potential of mesenchymal stem cells derived from diabetic rats by photobiomodulation therapy

Autologous cell-based therapy for bone regeneration might be impaired by diabetes mellitus (DM) due to the negative effects on mesenchymal stem cells (MSCs) differentiation. Strategies to recover their osteogenic potential could optimize the results. We aimed to evaluate the effect of photobiomodulation (PBM) therapy on osteoblast differentiation of rats with induced DM. Bone marrow MSCs of healthy and diabetic rats were isolated and differentiated into osteoblasts (OB and dOB, respectively). dOB were treated with PBM therapy every 72 hour (660 nm; 0.14 J; 20 mW; 0.714 W/cm² , and 5 J/cm² ). Cell morphology, viability, gene and protein expression of osteoblastic markers, alkaline phosphatase (ALP) activity, and the mineralized matrix production of dOB-PBM were compared to dOB. PBM therapy improved viability of dOB, increased the gene and protein expression of bone markers, the ALP activity and the mineralized matrix production. PBM therapy represents an innovative therapeutic approach to optimize the treatment of bone defects in diabetic patients.

Role of embryonic origin on osteogenic potential and bone repair capacity of rat calvarial osteoblasts

INTRODUCTION

The aim of this study was to evaluate the in vitro osteogenic potential of osteoblasts from neural crest-derived frontal bone (OB-NC) and mesoderm-derived parietal bone (OB-MS) and the bone formation induced by them when injected into calvarial defects.

MATERIALS AND METHODS

Calvarial bones were collected from newborn Wistar rats (3-day old) and characterized as frontal and parietal prior to OB-NC and OB-MS harvesting. The cells were cultured, and several parameters of osteoblast differentiation were evaluated. These cells, or PBS without cells (control), were locally injected into 5-mm rat calvarial defects (5 × 10⁶ cells/defect) and after 4 weeks bone formation was evaluated by morphometric and histological analyses.

RESULTS

The characterization of frontal and parietal bones assured the different embryonic origin of both cell populations, OB-NC and OB-MS. The OB-NC presented higher proliferation while the OB-MS presented higher alkaline phosphatase (ALP) activity, extracellular matrix mineralization and gene expression of runt-related transcription factor 2, Alp, bone sialoprotein and osteocalcin revealing their high osteogenic potential. µCT analysis indicated that there was higher amount of bone formation in defects injected with both OB-NC and OB-MS compared to the control. Moreover, the bone tissue formed by both cells displayed the same histological characteristics.

CONCLUSIONS

Despite the distinct in vitro osteogenic potential, OB-NC and OB-MS induced similar bone repair in a rat calvarial defect model. Thus, osteoblasts, irrespective of their in vitro osteogenic potential linked to embryonic origins, seem to be suitable for cell-based therapies aiming to repair bone defects.

Effect of focal adhesion kinase inhibition on osteoblastic cells grown on titanium with different topographies

Objective

The present study aimed to investigate the participation of focal adhesion kinases (FAK) in interactions between osteoblastic cells and titanium (Ti) surfaces with three different topographies, namely, untreated (US), microstructured (MS), and nanostructured (NS).

Methodology

Osteoblasts harvested from the calvarial bones of 3-day-old rats were cultured on US, MS and NS discs in the presence of PF-573228 (FAK inhibitor) to evaluate osteoblastic differentiation. After 24 h, we evaluated osteoblast morphology and vinculin expression, and on day 10, the following parameters: gene expression of osteoblastic markers and integrin signaling components, FAK protein expression and alkaline phosphatase (ALP) activity. A smooth surface, porosities at the microscale level, and nanocavities were observed in US, MS, and NS, respectively.

Results

FAK inhibition decreased the number of filopodia in cells grown on US and MS compared with that in NS. FAK inhibition decreased the gene expression of Alp, bone sialoprotein, osteocalcin, and ALP activity in cells grown on all evaluated surfaces. FAK inhibition did not affect the gene expression of Fak, integrin alpha 1 ( Itga1 ) and integrin beta 1 ( Itgb1 ) in cells grown on MS, increased the gene expression of Fak in cells grown on NS, and increased the gene expression of Itga1 and Itgb1 in cells grown on US and NS. Moreover, FAK protein expression decreased in cells cultured on US but increased in cells cultured on MS and NS after FAK inhibition; no difference in the expression of vinculin was observed among cells grown on all surfaces.

Conclusions

Our data demonstrate the relevance of FAK in the interactions between osteoblastic cells and Ti surfaces regardless of surface topography. Nanotopography positively regulated FAK expression and integrin signaling pathway components during osteoblast differentiation. In this context, the development of Ti surfaces with the ability to upregulate FAK activity could positively impact the process of implant osseointegration.

Effect of stem cells combined with a polymer/ceramic membrane on osteoporotic bone repair

Cell therapy associated with guided bone regeneration (GBR) can be used to treat bone defects under challenging conditions such as osteoporosis. This study aimed to evaluate the effect of mesenchymal stem cells (MSCs) in combination with a poly(vinylidene-trifluoroethylene)/barium titanate (PVDF-TrFE/BT) membrane on bone repair in osteoporotic rats. Osteoporosis was induced in female rats by bilateral removal of the ovaries (OVX) or sham surgery (SHAM), and the osteoporotic condition was characterized after 5 months by microtomographic and morphometric analyses. Calvarial defects were created in osteoporotic rats that immediately received the PVDF-TrFE/BT membrane. After 2 weeks, bone marrow-derived MSCs from healthy rats, characterized by the expression of surface markers using flow cytometry, or phosphate-buffered saline (PBS) (Control) were injected into the defects and bone formation was evaluated 4 weeks post-injection by microtomographic, morphometric, and histological analyses. A reduction in the amount of bone tissue in the femurs of OVX compared with SHAM rats confirmed the osteoporotic condition of the experimental model. More bone formation was observed when the defects were injected with MSCs compared to that with PBS. The modification that we are proposing in this study for the classical GBR approach where cells are locally injected after a membrane implantation may be a promising therapeutic strategy to increase bone formation under osteoporotic condition.

Effect of cell therapy with allogeneic osteoblasts on bone repair of rat calvaria defects

BACKGROUND AIMS

Regenerative medicine strategies based on cell therapy are considered a promising approach to repair bone defects. The aims of this study were to evaluate the effect of subculturing on the osteogenic potential of osteoblasts derived from newborn rat calvaria and the effect of these osteoblasts on bone repair of rat calvaria defects.

METHODS

Cells were obtained from 50 newborn rat calvaria, and primary osteoblasts (OB) were compared with first passage (OB-P1) in terms of osteogenic potential by assaying cell proliferation, alkaline phosphatase (ALP) activity, extracellular matrix mineralization and gene expression of the osteoblastic markers RUNX2, ALP, osteocalcin and bone sialoprotein. Then, 5-mm calvaria defects were created in 24 Wistar rats, and after 2 weeks, they were locally injected with 50 µL of phosphate-buffered saline containing either 5 × 10⁶ osteoblasts (OB-P1, n = 12) or no cells (control, n = 12). Four weeks post-injection, the bone formation was evaluated by micro-computed tomography and histological analyses. Data were compared by analysis of variance, followed by the Student-Newman-Keuls's test or Student's t-test (P ≤ 0.05).

RESULTS

OB-P1 showed high proliferation and ALP activity, and despite the reduced gene expression of osteoblastic markers and extracellular matrix mineralization compared with OB, they displayed osteogenic potential, being a good choice for injection into calvaria defects. The micro-tomographic and histological data showed that defects treated with OB-P1 presented higher bone formation compared with control defects.

DISCUSSION

Our results indicate that cells derived from newborn rat calvaria retain osteoblastic characteristics after subculturing and that these osteoblasts stimulate bone repair in a rat calvaria defect model.

Association of mesenchymal stem cells and osteoblasts for bone repair

Aim: We tested the hypothesis that the association of bone marrow mesenchymal stem cells (MSCs) and osteoblasts (OBs) optimize bone repair. Materials & Methods: MSCs were cultured in growth or osteogenic medium and seeded into gelatin sponge prior to implantation. Defects were created into rat calvariae and implanted with gelatin sponge without cells, with MSCs, with OBs and with association of MSCs and OBs. Histological analysis and micro-CT-based histomorphometry were carried out after 4 weeks. Results: Increased bone formation was observed in defects treated with cells and bone volume was greater in defects treated with either OBs or MSCs/OBs. Conclusion: Association of MSCs and OBs did not increase the process of bone repair compared with cell-based therapy using either MSCs or OBs alone.