MMP2 and ocular melanoma: We previously demonstrated that after ischemic and hypoxic preconditioning of OM-MSCs, the expression of a series of paracrine factors was changed, such as vascular endothelial growth factor, nerve growth factor, brain derived neurotrophic factor, glial cell line-derived neurotrophic factor and matrix metalloproteinase-2, all of which play an important role in the biological functions of MSCs.