Associate Professor Columbia University New York, New York, United States
Introduction:: After injury, tendon function is often compromised due to poor healing and failure to regenerate native structure. Due to limited treatment options, there is an unmet clinical need for effective therapies that promote tendon healing and functional restoration. However, our incomplete understanding of tendon biology prevents the design of therapeutics that activate regenerative pathways involved in tendon formation. In particular, two major obstacles exist: (1) the critical regulators of tendon induction and differentiation are unknown and (2) the regulators driving non-regenerative adult tendon healing have not been elucidated or overcome. We address these limitations using pluripotent stem cells to model tendon development and identify key regulators of tenogenesis.
Materials and Methods:: We established robust differentiation protocols to derive tenocytes from mouse embryonic stem cells (mESCs) and human induced pluripotent stem cells (hiPSCs) from step-wise differentiation through relevant developmental lineages. RNA-seq and scRNA-seq were used to validate models and identify transcriptional regulators. To test mechanotransduction pathways, small molecules were applied targeting MRTF and YAP/TAZ signaling.
Results, Conclusions, and Discussions:: Applying an iterative approach informed by scRNA-seq, we established highly efficient differentiation toward tendon and fibrocartilage tissues by targeting the retinoic acid and TGFbeta pathways. Trajectory analysis of RNA-seq datasets revealed novel transcription factors associated with fibrous tissue differentiation, which were validated in mouse embryonic tendons. We also identified a potential role for MRTF signaling in tendon mechanotransduction during embryogenesis.
Acknowledgements (Optional): : We acknowledge our funding sources NIH/NIAMS R21 AR078966, R01 AR081673, and R01 AR081674