Osteogenic activity of bone marrow-derived mesenchymal stem cells (BMSCs) seeded on irradiated allogenic bone

Irradiation Haematopoiesis Recovery Orchestrated by IL-12/IL-12Rβ1/TYK2/STAT3-Initiated Osteogenic Differentiation of Mouse Bone Marrow-Derived Mesenchymal Stem Cells

Purpose

Repairing the irradiation-induced osteogenic differentiation injury of bone marrow mesenchymal stem cells (BM-MSCs) is beneficial to recovering haematopoiesis injury in radiotherapy; however, its mechanism is elusive. Our study aimed to help meet the needs of understanding the effects of radiotherapy on BM-MSC osteogenic potential.

Methods and Materials

Balb/c mice and the BM-MSCs were used to evaluate the irradiation-induced osteogenic differentiation injury in vivo. The cellular and molecular characterization were applied to determine the mechanism for recovery of irradiation-derived haematopoiesis injuries.

Results

We report a functional role of IL-12 in acute irradiation hematopoietic injury recovery and intend to dissect the possible mechanisms through BM-MSC, other than the direct effect of IL-12 on hematopoietic stem and progenitor cells (HSPCs). Specifically, we show that early use of IL-12 enhanced the osteogenic differentiation of BM-MSCs through IL-12Rβ1/TYK2/STAT3 signaling; furthermore, IL-12 induced osteogenesis facilitated bone formation and irradiation hematopoiesis recovery when transplanted BM-MSCs in the femur of Balb/c mice. For the mechanism of action, we found that IL-12 receptor beta 1 (IL-12Rβ1) expression of irradiated BM-MSCs was upregulated rapidly, coincidentally consistent with early use of IL-12 induced osteogenic differentiation enhancement. IL-12Rβ1 and tyrosine kinase 2 gene (Tyk2) silencing experiments and phosphotyrosine of signal transducer and activator of transcription 3 (p-STAT3) suppression experiments indicated the IL-12Rβ1/TYK2/STAT3 signaling was essential in IL-12-induced osteogenic differentiation enhancement of BM-MSCs.

Conclusion

These findings suggested that IL-12 may exert BM-MSCs-based hematopoietic recovery by repairing osteogenic differentiation abilities damages through IL-12Rβ1/TYK2/STAT3 signaling pathway post-irradiation.

Bone Regeneration, Reconstruction and Use of Osteogenic Cells; from Basic Knowledge, Animal Models to Clinical Trials

The deterioration of the human skeleton's capacity for self-renewal occurs naturally with age. Osteoporosis affects millions worldwide, with current treatments including pharmaceutical agents that target bone formation and/or resorption. Nevertheless, these clinical approaches often result in long-term side effects, with better alternatives being constantly researched. Mesenchymal stem cells (MSCs) derived from bone marrow and adipose tissue are known to hold therapeutic value for the treatment of a variety of bone diseases. The following review summarizes the latest studies and clinical trials related to the use of MSCs, both individually and combined with other methods, in the treatment of a variety of conditions related to skeletal health. For example, some of the most recent works noted the advantage of bone grafts based on biomimetic scaffolds combined with MSC and growth factor delivery, with a greatly increased regeneration rate and minimized side effects for patients. This review also highlights the continuing research into the mechanisms underlying bone homeostasis, including the key transcription factors and signalling pathways responsible for regulating the differentiation of osteoblast lineage. Paracrine factors and specific miRNAs are also believed to play a part in MSC differentiation. Furthering the understanding of the specific mechanisms of cellular signalling in skeletal remodelling is key to incorporating new and effective treatment methods for bone disease.

Supplying osteogenesis to dead bone using an osteogenic matrix cell sheet

PURPOSE

To evaluate whether osteogenic matrix cell sheets can supply osteogenesis to dead bone.

METHODS

Femur bone fragments (5 mm in length) were obtained from Fisher 344 rats and irradiated by a single exposure of 60 Gy to produce bones that were no longer viable. Osteogenic matrix cell sheets were created from rat bone marrow-derived stromal cells (BMSCs). After wrapping the dead bone with an osteogenic matrix cell sheet, it was subcutaneously transplanted into the back of a rat and harvested after 4 weeks. Bone formation around the dead bone was evaluated by X-ray imaging and histology. Alkaline phosphatase (ALP) and osteocalcin (OC) mRNA expression levels were measured to confirm osteogenesis of the transplanted bone. The contribution of donor cells to bone formation was assessed using the Sry gene and PKH26.

RESULTS

After the cell sheet was transplanted together with dead bone, X-ray images showed abundant calcification around the dead bone. In contrast, no newly formed bone was seen in samples that were transplanted without the cell sheet. Histological sections also showed newly formed bone around dead bone in samples transplanted with the cell sheet, whereas many empty lacunae and no newly formed bone were observed in samples transplanted without the cell sheet. ALP and OC mRNA expression levels were significantly higher in dead bones transplanted with cell sheets than in those without a cell sheet (P < 0.01). Sry gene expression and cells derived from cell sheets labeled with PKH26 were detected in samples transplanted with a cell sheet, indicating survival of donor cells after transplantation.

CONCLUSION

Our study indicates that osteogenic matrix cell sheet transplantation can supply osteogenesis to dead bone.

Differentiation of Human Amniotic Mesenchymal Stem Cells into Human Anterior Cruciate Ligament Fibroblast Cells by In Vitro Coculture

Anterior cruciate ligament injuries are common in humans, though cellular components of the knee have little regenerative or proliferation potential. This study investigated the differentiation of human amnion-derived mesenchymal stem cells (hAMSCs) into human anterior cruciate ligament fibroblasts (hACLFs) in vitro through induction with bFGF and TGF-β1 with coculture systems. Groups A and B comprised hAMSCs at the 3rd passage cultured with and without bFGF and TGF-β1, respectively; Groups C and D consisted of hAMSCs and hACLFs in monolayer coculture with and without bFGF and TGF-β1, respectively; Groups E and F were composed of hAMSCs and hACLFs in Transwell coculture with and without bFGF and TGF-β1, respectively. Cell morphology and proliferation were recorded. Protein expression and relative mRNA expression were evaluated in each group. Cell proliferation was significantly higher in the induced groups than in the noninduced groups. Protein expression increased over time with the highest expression observed in Group E. mRNA levels were significantly higher in Group E than in other groups. This study is the first to demonstrate the use of the Transwell coculture system for this purpose, and hAMSCs were successfully differentiated into hACLFs. Thus, hAMSCs may be a superior choice for hACLF differentiation via Transwell coculture.

Culturing bone marrow cells with dexamethasone and ascorbic acid improves osteogenic cell sheet structure

Objectives

To assess the structure and extracellular matrix molecule expression of osteogenic cell sheets created via culture in medium with both dexamethasone (Dex) and ascorbic acid phosphate (AscP) compared either Dex or AscP alone.

Methods

Osteogenic cell sheets were prepared by culturing rat bone marrow stromal cells in a minimal essential medium (MEM), MEM with AscP, MEM with Dex, and MEM with Dex and AscP (Dex/AscP). The cell number and messenger (m)RNA expression were assessed in vitro, and the appearance of the cell sheets was observed after mechanical retrieval using a scraper. β-tricalcium phosphate (β-TCP) was then wrapped with the cell sheets from the four different groups and subcutaneously implanted into rats.

Results

After mechanical retrieval, the osteogenic cell sheets from the MEM, MEM with AscP, and MEM with Dex groups appeared to be fragmented or incomplete structures. The cell sheets cultured with Dex/AscP remained intact after mechanical retrieval, without any identifiable tears. Culture with Dex/AscP increased the mRNA and protein expression of extracellular matrix proteins and cell number compared with those of the other three groups. More bridging bone formation was observed after transplantation of the β-TCP scaffold wrapped with cell sheets cultured with Dex/AscP, than in the other groups.

Conclusions

These results suggest that culture with Dex/AscP improves the mechanical integrity of the osteogenic cell sheets, allowing retrieval of the confluent cells in a single cell sheet structure. This method may be beneficial when applied in cases of difficult tissue reconstruction, such as nonunion, bone defects, and osteonecrosis.

Cite this article: M. Akahane, T. Shimizu, T. Kira, T. Onishi, Y. Uchihara, T. Imamura, Y. Tanaka. Culturing bone marrow cells with dexamethasone and ascorbic acid improves osteogenic cell sheet structure. Bone Joint Res 2016;5:569–576. DOI: 10.1302/2046-3758.511.BJR-2016-0013.R1.

Potency Biomarker Signature Genes from Multiparametric Osteogenesis Assays: Will cGMP Human Bone Marrow Mesenchymal Stromal Cells Make Bone?

In skeletal regeneration approaches using human bone marrow derived mesenchymal stromal cells (hBM-MSC), functional evaluation before implantation has traditionally used biomarkers identified using fetal bovine serum-based osteogenic induction media and time courses of at least two weeks. However, emerging pre-clinical evidence indicates donor-dependent discrepancies between these ex vivo measurements and the ability to form bone, calling for improved tests. Therefore, we adopted a multiparametric approach aiming to generate an osteogenic potency assay with improved correlation. hBM-MSC populations from six donors, each expanded under clinical-grade (cGMP) conditions, showed heterogeneity for ex vivo growth response, mineralization and bone-forming ability in a murine xenograft assay. A subset of literature-based biomarker genes was reproducibly upregulated to a significant extent across all populations as cells responded to two different osteogenic induction media. These 12 biomarkers were also measurable in a one-week assay, befitting clinical cell expansion time frames and cGMP growth conditions. They were selected for further challenge using a combinatorial approach aimed at determining ex vivo and in vivo consistency. We identified five globally relevant osteogenic signature genes, notably TGF-ß1 pathway interactors; ALPL, COL1A2, DCN, ELN and RUNX2. Used in agglomerative cluster analysis, they correctly grouped the bone-forming cell populations as distinct. Although donor #6 cells were correlation slope outliers, they contrastingly formed bone without showing ex vivo mineralization. Mathematical expression level normalization of the most discrepantly upregulated signature gene COL1A2, sufficed to cluster donor #6 with the bone-forming classification. Moreover, attenuating factors causing genuine COL1A2 gene down-regulation, restored ex vivo mineralization. This suggested that the signature gene had an osteogenically influential role; nonetheless no single biomarker was fully deterministic whereas all five signature genes together led to accurate cluster analysis. We show proof of principle for an osteogenic potency assay providing early characterization of primary cGMP-hBM-MSC cultures according to their donor-specific bone-forming potential.

Effects of bone marrow-derived mesenchymal stem cells on the autophagic activity of alveolar macrophages in a rat model of silicosis

The aim of the present study was to evaluate the effects of bone marrow-derived mesenchymal stem cells (BMSCs) on the expression of the autophagy-associated proteins, microtubule-associated protein light chain 3 (LC-3) and autophagy-related gene Beclin-1 (Beclin-1), in alveolar macrophages (AMs) in a rat model of silicosis. Furthermore, the study investigated the molecular mechanisms underlying the effects of BMSC treatment. A population of 60 adult female Sprague-Dawley (SD) rats were allocated at random into three groups, namely the control, model and BMSC treatment groups (n=20 per group). BMSCs were isolated from five male SD rats (age, 6-8 weeks) and cultured in vitro. The silicosis model was established using a single 1.0-ml infusion of silicon dioxide suspension administered via non-exposed tracheal intubation. Rats in the BMSC treatment group received a 1.0-ml transplantation of BMSCs (1×106/ml). The rats were sacrificed on days 1, 7, 14 and 28 after modeling, and AMs were extracted from the rats using bronchoalveolar lavage. Third-generation BMSCs were identified using flow cytometry with fluorescein isothiocyanate staining, and the morphological characteristics of the AMs were observed using hematoxylin and eosin staining. The expression levels of LC-3 and Beclin-1 were determined using immunocytochemistry sand western blot analysis. The expression levels of LC-3 and Beclin-1 were found to be increased at all the time points in the model group. LC-3 and Beclin-1 levels began to increase at day 1, peaked at day 14 and decreased after day 28; however, the levels remained elevated compared with the basal expression levels. The AMs of the BMSC treatment group exhibited significantly alleviated pathological symptoms compared with the model group AMs, as indicated by significantly decreased expression levels of LC-3 and Beclin-1 at each time point. Therefore, the results indicated that autophagy was promoted in the AMs of the silicosis model rats. Furthermore, treatment with BMSCs was demonstrated to reduce the expression levels of LC-3 and Beclin-1, subsequently inhibiting autophagic activity and mitigating the damage associated with silicosis.