Tenogenic differentiation of equine mesenchymal progenitor cells under indirect co-culture.

Purpose: Adult bone marrow mesenchymal stem cells (BM-MSCs) are a potential cell source for tendon repair in direct cell therapy and tissue engineering investigations. The purpose of this study was to evaluate the tenogenic induction of undifferentiated BM-MSCs under indirect co-culture technique with trimmed native tendon tissue. Since the horse represents a preferred species to study tendon regenerative strategies, this work was conducted on equine BM-MSCs. Methods: Equine BM-MSCs were co-cultured in a transwell system with tendon tissue fragments. The BM-MSC tenogenic differentiation was evaluated by cytochemical staining and real time PCR for gene expression. Cell viability in tendon fragments and cultured cells was analyzed. Results: Our results indicate that under indirect co-culture with native and healthy tendon tissue the BM-MSCs expressed tendon-specific markers such as decorin, tenomodulin, tenascin-C, and collagen type I. They also retained a tenocyte-like phenotype during monolayer culture. Conclusions: Data are very encouraging for future in vitro investigations into committing cells to the tenogenic lineage without adding growth factors or serum to the culture medium for both cell therapy and tissue engineering.