Phenotypic similarity of spheroids of native chondrocytes and spheroids of chondrocytes differentiated from human induced pluripotent stem cells using recombinant factors TGF-β1 and BMP2

BACKGROUND: Chronic joint diseases represent a significant medical and social problem due to their high prevalence, frequent patient disability, and associated economic losses. Potential therapeutic approaches include cell-based technologies utilizing autologous chondrocytes, which are surgically harvested and expanded in vitro before transplantation. Recently, the 3D chondrocyte culturing technique in the form of spheroids has been increasingly used, as it better preserves the functional state of chondrocytes and creates favorable conditions for high-quality cartilage maturation. However, the quantity and quality of autologous chondrocytes may be insufficient to generate an adequate amount of cellular material to fully repair large articular cartilage defects. An alternative cell source could be chondrocytes derived from induced pluripotent stem cells. AIM: To perform an immunophenotypic comparison of spheroids composed of native chondrocytes and spheroids of chondrocytes differentiated from human induced pluripotent stem cells. MATERIALS AND METHODS: This study presents detailed protocols for generating spheroids of native chondrocytes and spheroids of induced pluripotent stem cells–derived chondrocytes using mini-bioreactors and recombinant TGF-β1 and BMP2 factors. Using immunocytochemical staining and quantitative reverse transcription polymerase chain reaction, we compared native chondrocyte spheroids and spheroids of chondrocytes differentiated from induced pluripotent stem cells in terms of the expression of key chondrogenic genes: aggrecan (ACAN), collagen types I (COL1A2) and II (COL2A1), and the key transcription factor SOX9. RESULTS: The expression levels of chondrogenic genes in induced pluripotent stem cells–derived chondrocyte spheroids closely resembled those in native chondrocyte spheroids, except for a significantly increased expression of type I collagen (COL1A2). CONCLUSION: The use of induced pluripotent stem cells–derived chondrocyte spheroids represents a promising approach for the treatment of chronic joint diseases.