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N. Trivedi, J. Hollister-Lock, M. D. Lopez-Avalos, J. J. O’Neil, M. Keegan, S. Bonner-Weir, G. C. Weir, Increase in β-Cell Mass in Transplanted Porcine Neonatal Pancreatic Cell Clusters Is Due to Proliferation of β-Cells and Differentiation of Duct Cells, Endocrinology, Volume 142, Issue 5, 1 May 2001, Pages 2115–2122, https://doi.org/10.1210/endo.142.5.8162
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Abstract
A 20-fold increase in β-cell mass has been found after transplantation of porcine neonatal pancreatic cell clusters (NPCCs). Here the mechanisms leading to this increased β-cell mass were studied. NPCCs (4000 islet equivalents) generated after 8 days culture of digested neonatal pig pancreas were transplanted beneath the renal capsule of streptozotocin (STZ) diabetic and normoglycemic nude mice. Grafts were removed at 10 days, 6 weeks, and 20 weeks after transplantation for immunostaining and insulin content. Proliferation of β-cells and duct cells was assessed morphometrically using double immunostaining for Ki-67 with insulin or cytokeratin 7 (CK7). Graft maturation was assessed with double immunostaining of CK7 and insulin. Apoptosis was determined using propidium iodide staining. β-cell proliferation in NPCCs was higher after 8 days of culture compared with that found in neonatal pig pancreas. After transplantation, β-cell proliferation remained high at 10 days, decreased somewhat at 6 weeks, and was much lower 20 weeks after transplantation. Diabetic recipients not cured at 6 weeks after transplantation had significantly higherβ -cell proliferation compared with those cured and to normoglycemic recipients. The size of individual β-cells, as determined by cross-sectional area, increased as the grafts matured. Graft insulin content was 20-fold increased at 20 weeks after transplantation compared with 8 days cultured NPCCs. The proliferation index of duct cells was significantly higher in neonatal pig pancreas than in 8 days cultured NPCCs and in 10-day-old grafts. The incidence of apoptosis in duct cells appeared to be low. About 20% of duct cells 10 days post transplantation showed costaining for CK7 and insulin, a marker of protodifferentiation. In conclusion, the increase in β-cell mass after transplantation of NPCCs is due to both proliferation of differentiated β-cells and differentiation of duct cells intoβ -cells.
