Donor-dependent heterogeneity and matrix-remodeling transcriptional programs in COL2A1-variant urine-derived cell...

COL2A1-associated skeletal dysplasias affect cartilage extracellular matrix and endochondral growth, but patient growth-plate tissue is largely inaccessible. We generated chondrogenically induced urine-derived cells (chUDCs) from three individuals with heterozygous pathogenic COL2A1 variants and three healthy controls. Classical differentiation was assessed by Alcian blue and Alizarin red staining, bulk RNA sequencing compared patient-derived and control chUDCs, and single-cell RNA sequencing was performed in two patient-derived lines. COL2A1-mutant chUDCs retained overt chondrogenic and osteogenic staining capacity without a clear patient-control separation. In contrast, bulk RNA sequencing identified a small set of consistently differential extracellular-matrix remodeling genes enriched for matrix and ossification-related programs; DDR2 and ADAMTS5 remained significant in leave-one-donor-out, age-adjusted and cell-composition-adjusted models. Single-cell profiling resolved multiple chUDC states, including chondrogenic, fibroblastic extracellular-matrix, IGF1R-high, and osteogenic-associated states. IGF1 co-treatment was associated with reduced osteogenic-associated module scores and increased fibroblastic/anabolic extracellular-matrix programs. Because no IGF1-treated control-donor line was profiled, IGF1-associated changes are reported as exploratory and are not claimed to be COL2A1-specific. These findings support chUDCs as a non-invasive system for exploring selected transcriptional programs relevant to cartilage biology and growth-factor responsiveness in COL2A1-associated growth disorders.