The pathogenesis of osteoarthritis often begins from an injury such as a focal defect to articular cartilage, which establishes chronic, low-grade inflammation that eventually results in degenerative joint disease. Pluripotent stem cell-derived articular chondrocytes represent a promising new tool for articular cartilage repair.
Research-grade human pluripotent stem cells (hPSC) were differentiated into immature articular chondrocytes using protocols previously established in our lab. Generated hPSC-derived chondrocytes (hPSDC) were seeded onto clinical grade collagen 1/3 membranes (hPSDC-M) and evaluated using single-cell RNA-sequencing to characterize and assess the developmental status. Potential of engraftment of the hPSDC-M was assessed in a porcine model, where 6-mm full thickness defects were generated in the articular cartilage of male Yucatan minipigs.
Our studies have shown that transcriptional signatures of hPSDC-M via single cell sequencing closely resemble embryonic and juvenile stages of human chondrocyte ontogeny, suggesting an immature chondrogenic identity. Our porcine model also demonstrated that implanted hPSDC-M engrafted and contributed to the generation of comparable articular cartilage tissue endogenously found when compared to the membranes alone. Engrafted human chondrocytes were clearly detectable at 6 months after implantation in all tested animals. Biomechanical assessment after 6 months confirmed that the cartilage containing the hPSDC-M showed significant improvement in cartilage surface biomechanical properties compared to the membrane alone. which, and positively stained for GAGs, PRG4, collagen 2, and SOX9 via IHC. Human hPSDC-M secreted nearly 10-fold more BMP2 than BMSCs indicating that pluripotent stem cells closely resemble chondroinductive signature of early perichondrium, while adult MSCs lacked this potential.
Both the functionality by engraftment of these immature chondrocytes and their paracrine activity contribute to the value of hPSDC-M, which has the potential to enact articular cartilage repair as a universal, off-the-shelf product from an inexhaustible source of chondrogenic cells.