Chondrogenesis Of Progenitor Cells Research Articles

Osmolarity determines the in vitro chondrogenic differentiation capacity of progenitor cells via nuclear factor of activated T-cells 5

IntroductionPrevious studies have shown that human articular chondrocytes in vitro are osmolarity-responsive and increase matrix synthesis under cartilage-specific physiological osmolarity. The effects of increased osmolarity on chondrogenesis of progenitor cells in vitro are largely unknown. We therefore aimed to elucidate whether hyperosmolarity facilitates their chondrogenic differentiation and whether Nfat5 is involved. Materials and methodsATDC5 cells and human bone marrow stem cells (hBMSCs) were differentiated in the chondrogenic lineage in control and increased osmolarity conditions. Chondrogenic outcome was measured by gene- and protein expression analysis. RNAi was used to determine the role of Nfat5 in chondrogenic differentiation under normal and increased osmolarity. ResultsIncreasing the osmolarity of differentiation medium with 100mOsm resulted in significantly increased chondrogenic marker expression (Col2a1, Col10a1, Acan, Sox9, Runx2 and GAGs) during chondrogenic differentiation of the two chondroprogenitors, ATDC5 and hBMSCs. Nfat5 knockdown under both control and increased osmolarity affected chondrogenic differentiation and suppressed the osmolarity-induced chondrogenic induction. Knockdown of Nfat5 in early differentiation significantly decreased early Sox9 expression, whereas knockdown of Sox9 in early differentiation did not affect early Nfat5 expression. ConclusionsIncreasing the osmolarity of chondrogenic culture media by 100mOsm significantly increased chondrogenic gene expression during the course of chondrogenic differentiation of progenitor cells. Nfat5 may be involved in regulating chondrogenic differentiation of these cells under both normal and increased osmolarities and might regulate chondrogenic differentiation through influencing early Sox9 expression.

BMP-2 and BMP-7: differential regulation of chondrogenic differentiation

BMP-2 and BMP-7: differential regulation of chondrogenic differentiation

Cartilage Tissue Engineering; Lessons Learned From Periosteum

Cartilage, due to its unique physiology (lack of vasculature), can be potentially repaired using tissue engineered in the laboratory, by combining cells and with a supporting scaffold. This requires a marriage between material science, cell biology, and translational medicine, a concept well established as Tissue Engineering. Over the years the in vivo and in vitro chondrogenic potential of periosteum has been recognised by many researchers and as such periosteum is explored both to repair cartilage defects directly by transplanting periosteum into the cartilage defect or by using periosteum as a cell source for cartilage engineering purposes. The initial example hereof is the first generation of Autologous Chondrocyte Transplantation. Graft hypertrophy and ossification remain the primary drawbacks of cartilage repair strategies using engineered cartilage. These drawbacks may (partially) be due to the endochondral ossification process that can take over when cartilage is repaired. In this process chondrogenesis of progenitor cells is followed by hypertrophy of these cells and subsequent ossification. Periosteal progenitor cells go through this process in order to heal bone fractures. This review provides an overview of the role of periosteum in cartilage repair and cartilage tissue engineering and illustrates how periosteum can be used as a model to study the endochondral process. Such studies may provide clues to further optimize cartilage tissue engineering by identifying important factors which are capable of maintaining cells in their chondrogenic phenotype. Finally, the use of periosteum to engineer cartilage in vivo at an extra-articular site is described.

Gene Transfer and Living Release of Transforming Growth Factor-β3 for Cartilage Tissue Engineering Applications

Cartilage restoration continues to present a tremendous clinical challenge due to its nonvascular nature. Many studies have demonstrated that chondrogenesis of progenitor cells can be achieved in vitro by manual dose of growth factors; however, it remains a vital difficulty in feeding growth factors to implanted therapeutic cells in vivo. Herein, we constructed recombinant adenovirus encoding human transforming growth factor-beta3 (hTGF-beta3) and practiced it in rat bone marrow-derived mesenchymal stromal cells and articular chondrocytes for cartilage regeneration. Optimal viable transduction and transgenic hTGF-beta3 production were achieved; consequently, positive expression of cartilage marker-collagen type II was enabled in the infected progenitors. We thus conclude that recombinant adenovirus encoding TGF-beta3 gene has been successfully established and validated for cartilage tissue engineering applications.

Evaluation of adult equine bone marrow‐ and adipose‐derived progenitor cell chondrogenesis in hydrogel cultures

Bone marrow mesenchymal stem cells (BM-MSCs) and adipose-derived progenitor cells (ADPCs) are potential alternatives to autologous chondrocytes for cartilage resurfacing strategies. In this study, the chondrogenic potentials of these cell types were compared by quantifying neo-tissue synthesis and assaying gene expression and accumulation of extracellular matrix (ECM) components of cartilage. Adult equine progenitor cells encapsulated in agarose or self-assembling peptide hydrogels were cultured in the presence or absence of TGFbeta1 for 3 weeks. In BM-MSCs-seeded hydrogels, TGFbeta1 stimulated ECM synthesis and accumulation 3-41-fold relative to TGFbeta1-free culture. In ADPC cultures, TGFbeta1 stimulated a significant increase in ECM synthesis and accumulation in peptide (18-29-fold) but not agarose hydrogels. Chromatographic analysis of BM-MSC-seeded agarose and peptide hydrogels cultured in TGFbeta1 medium showed extensive synthesis of aggrecan-like proteoglycan monomers. ADPCs seeded in peptide hydrogel also synthesized aggrecan-like proteoglycans, although to a lesser extent than seen in BM-MSC hydrogels, whereas aggrecan-like proteoglycan synthesis in ADPC-seeded agarose was minimal. RT-PCR analysis of TGFbeta1 cultures showed detectable levels of type II collagen gene expression in BM-MSC but not ADPC cultures. Histological analysis of TGFbeta1-cultured peptide hydrogels showed the deposition of a continuous proteoglycan- and type II collagen rich ECM for BM-MSCs but not ADPCs. Therefore, this study showed both protein and gene expression evidence of superior chondrogenesis of BM-MSCs relative to ADPCs.