VEGFA and osteoporosis: The alginate microparticle prevented the delivered VEGF to interact with the VEGF surface receptor (VEGFR), which could potentially direct hMSCs into the osteoblast linage rather than adipocytes.22 Liu et al. showed that the stealth delivery of VEGF effectively contributed in the differentiation signal pathway; they found that the intracellular expression of VEGFA but not external application of the growth factor could cure osteoporosis.212 As expected, hMSCs could endocytose VEGFA–microparticles within 48 h coculturing and differentiate into osteoblast after 14 d (Figure11).