Effect of pioglitazone on endogenous beta-cell regeneration.

(a) Overview of experimental design. Following treatment with STZ, diabetic mice (BG >400 mg/dl) received approximately 200 syngeneic C57BL/6 islets under the kidney capsule for 6 weeks (Islet Txp), and then underwent a nephrectomy to remove the transplanted islets. (b) BG was monitored every 1–2 weeks after nephrectomy and the number of mice with normoglycemia (<250 mg/dl) at ≥13 weeks post-STZ ± Pio treatment for 30 or 100 days (Pio-30D or Pio-100D) are indicated. Data are presented as mean (N = 11–16/group) ± standard error of mean (SEM). (c) After 4 h fasting, IPGTT was performed on only the mice with normoglycemia (<250 mg/dl) at ≥12 weeks post-STZ compared to control non-diabetic C57BL/6 mice. (d) Pancreatic beta-cell mass at week 2 post-STZ or week 14 post-STZ and islet transplant receiving CMC (No Rx) or Pio (25 mg/kg/day; Pio) of 3–4 randomly selected mice still alive and with normoglycemia (<250 mg/dl). Data are mean beta-cell mass of 3–4/group (mg/pancreas ± SEM).