Comparative Analysis of Tenogenic Gene Expression in Tenocyte-Derived Induced Pluripotent Stem Cells and Bone Marrow-Derived Mesenchymal Stem Cells in Response to Biochemical and Biomechanical Stimuli.

The tendon is highly prone to injury, overuse, or age-related degeneration in both humans and horses. Natural healing of injured tendon is poor, and cell-based therapeutic treatment is still a significant clinical challenge. In this study, we extensively investigated the expression of tenogenic genes in equine bone marrow mesenchymal stem cells (BMSCs) and tenocyte-derived induced pluripotent stem cells (teno-iPSCs) stimulated by growth factors (TGF-3 and BMP12) combined with ectopic expression of tenogenic transcription factor MKX or cyclic uniaxial mechanical stretch. Western blotting revealed that TGF-3 and BMP12 increased the expression of transcription factors SCX and MKX in both cells, but the tenocyte marker tenomodulin (TNMD) was detected only in BMSCs and upregulated by either inducer. On the other hand, quantitative real-time PCR showed that TGF-3 increased the expression of , , , and in BMSCs and , , , , and in teno-iPSCs. BMP12 treatment elevated , , , , and in teno-iPSCs. Overexpression of MKX increased , , , and in BMSCs and , , , , and in teno-iPSCs; TGF-3 further enhanced in BMSCs. Moreover, mechanical stretch increased , , , , and in BMSCs and , , , , , , and in teno-iPSCs; TGF-3 tended to further elevate , , and in BMSCs and , , , , and in teno-iPSCs, while BMP12 further uptrended the expression of and in BMSCs and in teno-iPSCs. Additionally, the aforementioned tenogenic inducers also affected the expression of signaling regulators , , and in BMSCs and teno-iPSCs. Taken together, our data demonstrate that, in respect to the tenocyte-lineage-specific gene expression, BMSCs and teno-iPSCs respond differently to the tenogenic stimuli, which may affect the outcome of their application in tendon repair or regeneration.