LAMA5 links extracellular matrix organization to a candidate WNT-associated endothelial signaling niche during human...

How extracellular matrix organization shapes signaling-associated transcription during skeletal development remains incompletely understood. Using CRISPR-Cas9-edited human urine-derived stem cells, we show that loss of the laminin gene LAMA5 preserves canonical chondrogenic marker induction but impairs three-dimensional spheroid morphogenesis and disrupts pericellular matrix architecture. Bulk RNA sequencing and weighted gene co-expression network analysis identify a LAMA5-associated transcriptional module enriched for embryonic limb morphogenesis genes, with WNT7A and FLI1 as inversely correlated hub genes. Projection onto a human fetal hindlimb atlas localizes LAMA5/WNT7A co-expression to the endothelial compartment, while PITX1 and FLI1 map to endothelial and chondrocyte populations, respectively, suggesting a spatially organized signaling axis partially conserved in mouse. Pharmacologic β-catenin stabilization partially restores selected module transcripts, and endothelial-conditioned medium selectively rescues WNT7A and CDH1 in LAMA5-KO cultures. Together, these data link LAMA5-dependent matrix organization to a WNT-associated transcriptional program and identify endothelium as a candidate niche source.