Human fetal pancreatic nestin positive cells cultured in vitro could self assemble to form islet-like cell clusters(ICC). They are multipotential and are capable of generating insulin-producing cells. To investigate their biological character and physiological function in vivo, ICCs were implanted into NOD-Scid mice subcapsularly. The results showed that: (1) Neovascularizations were observed in implant sites. (2) Blood glucose levels of diabetic mice were reduced markedly after implantation of ICCs. (3) ICCs in non-diabetic mice proliferated abnormally and infiltrated into renal parenchyma with many cell structures formed.