Human PSC-derived articular cartilage chondrocytes scRNA-seq

Objectives Traditional approaches to study Progressive Pseudorheumatoid Arthropathy of Childhood (PPAC) failed to uncover how loss-of-function mutations in Wnt inducible secreted protein 3 (WISP3) cause premature cartilage failure in children. We developed a human induced pluripotent stem cell (hiPSC)-based model of cartilage development to elucidate pathological changes in WISP3-deficient articular cartilage tissues compared to WISP3-sufficient isogenic cartilage tissues. Methods We generated iPSCs from 2 patients with PPAC, and we corrected the disease-causing mutation in one of these lines using CRISPR/Cas9. We also created a WISP3-knockout human embryonic stem cell line. We generated articular cartilage tissues from these hPSCs by established directed differentiation methods. Bioinformatic analyses were used to identify differentially expressed genes (DEGs) and cell type abundances, which were validated by quantitative RT-qPCR and in situ hybridization. Results WISP3-deficient articular cartilage tissues exhibited significantly different transcriptomic profiles and cellular composition compared with their isogenic controls. WISP3-deficient cartilage transcriptomes exhibited enriched biological processes such as TGFb signaling and epithelial to mesenchymal transition. We validated increased expression of TGFb-related genes in WISP3-deficient cartilage, and determined that the abundance of chondrocyte subtypes was altered compared with isogenic controls. Conclusions We developed a robust and reproducible model of iPSC-derived cartilage development to better understand the role of WISP3 in cartilage biology, and the pathology of cartilage failure associated with loss of WISP3 in patients with PPAC. We identified several altered biological processes and signaling pathways in WISP3-deficient cartilage that can be validated in the future with additional patient-derived cell lines, or large animal models. Overall design: comparative gene expression profiling of in vitro derived cartilage chrondrocytes from human PSCs Please note: Raw data are not available for the PPAC iPSC samples due to patient privacy concerns.