APLN and type 2 diabetes mellitus: Here, we confirmed that WJ-MSCs-apelin was able to enhance mobilization, survival, and proliferation of endogenous pancreatic ß cell in the injured islets of the pancreas, suggesting a novel additive or synergistic mechanism for possible explanation how WJ-MSCs-apelin might repair the pancreas islets and improve pancreatic ß cell function in T2D rats.