The results showed that hUC-MSC-EVs slowed down the progression of OA in mouse knee joints by decreasing the secretion of pro-inflammatory factors, reduced osteomalacia, increased the expression of collagen type II alpha 1 (COL2A1) and cluster gel, and inhibited the overexpression of thrombochondroitin-1-motif 5 (ADAMTS5) and MMP13. This evidence concerns the gene COL2A1 and osteomalacia.