Disclosed herein is a method of generating exosomes (extraceiliiiar nanovesicles) and/or neo-islets from mesenchymal or adipose stem cells or islets, or other cells in a Hollow-Fiber-based Cell Expansion (HFCE) System. Such exosomes and/or neo-islets may be used for the treatment of TIDM, T2DM, or associated microvascular disease.