Comparison of the chondrogenic potential of eBMSCs and eUCMSCs in response to selected peptides and compounds

Cartilage injuries pose significant challenges in horses and often lead to post-traumatic osteoarthritis (PTOA). Despite the advances in surgical and regenerative techniques, the result in most cases is the formation of a fibrocartilage repair tissue. Cell-based cartilage therapies are mainly focused on equine bone marrow-derived mesenchymal stem cells (eBMSCs) as they are easily accessible, and multipotent. Nonetheless, alternative allogeneic sources, for example equine umbilical cord matrix mesenchymal stromal cells (eUCMSCs), hold promise given their non-invasive and readily accessible nature. Considerable research has been dedicated to exploring chondroinductive factors (e.g., peptides and small compounds), aiming to replace growth factors for inducing chondrogenesis. However, these factors have not yet translated to the equine community. Therefore, in the current study, we selected from the literature two promising peptides, CM10 and CK2.1, and two promising compounds, kartogenin and SM04690, and assessed their chondroinductive potential with both eBMSCs and eUCMSCs. In addition, the chondroinductive potential of eBMSCs was evaluated in monolayer and spheroid culture in both hypoxia and normoxia in response to dexamethasone and/or transforming growth factor beta 3 (TGF-β3).

Following 21 days of culture, none of the evaluated chondrogenic factors resulted in a higher gene expression of chondrogenic markers compared to the positive or negative controls with eBMSCs or eUCMSCs. Interestingly, spheroid culture in hypoxia with dexamethasone treatment (without TGF-β or any compound or peptide) was sufficient to induce the chondrogenic differentiation of eBMSCs.

Based on cell response to the positive control, in the conditions employed in the current study, eBMSCs may be preferred over eUCMSCs for chondrogenesis. The current study supports the use of spheroid culture, and the use of dexamethasone over TGF-β or any of the compounds or peptides tested here from the prior literature to drive chondrogenesis with eBMSCs.