Supplementation of growth differentiation factor-5 increases proliferation and size of chondrogenic pellets of human umbilical cord-derived perivascular stem cells - Borim An; Hye-Ryeon Heo; Sungeun Lee; Jeong-Ah Park; Kye-Seong Kim; Jeonghee Yang; Seok-Ho Hong (Tissue Engineering and Regenerative Medicine, 2015)