Fig. 6

Muscle-derived stem cells (MDSC) differentiate in vivo into insulin-expressing cells 10 days after intraperitoneal injection in streptozotocin (STZ)-treated mice. To examine if undifferentiated MDSC could differentiate in vivo into functional beta cells, MDSC were isolated from a donor mouse expressing mCherry under the control of the rat INS2 promoter that expressed mCherry specifically in pancreatic beta cells as shown by co-immunostaining for insulin (green) (a). Recipient NOD-SCID-MIP-eGFP transgenic mice expressed eGFP under the control of the mouse INS1 promoter specifically in pancreatic beta cells as shown by co-staining for insulin (red) (b). Recipient MIP-eGFP mice were injected with the glucose analog STZ to destroy endogenous beta cells and 60 min later with either saline vehicle (STZ only) or MDSC (STZ + MDSC), and pancreatic vibratome sections were analyzed 10 days later. Panels in (c) show staining for eGFP (green) and mCherry (red, no signal) in a pancreatic islet of MIP-eGFP mouse 10 days after STZ injection alone. Panels in (d) show staining for eGFP (green) and mCherry (red) in an islet of MIP-eGFP mouse 10 days after injection of STZ and undifferentiated muscle stem cells from a RIP-mCherry donor mouse. Scale bars = 100 μm