Experimental Transplantation With Principal Islets of Teleost Fish (Brockmann Bodies): Long-Term Function of Tilapia Islet Tissue in Diabetic Nude Mice

Certain teleost fish have macroscopically visible islets called BBs that are anatomically discrete. BBs were harvested from Oreochromis nilotica (tilapia) with microscissors, divided, and cultured overnight at 37°C before transplantation into STZ-induced diabetic nude mice. Each mouse received BB fragments from 3-5 fish weighing in aggregate ∼1.7 kg. Non-FPGs were monitored 5 days/wk. Recipients remained normoglycemic (plasma glucose <11.1 mM) for 50 days posttransplantation. Mice bearing 50-day-old grafts had essentially normal GTTs. Left nephrectomies then were performed to remove the grafts, and plasma glucose levels in recipient mice rose to >22.2 mM. Histological examination of graft-bearing kidneys showed viable, vascularized islet tissue containing numerous well-granulated β-cells; examination of recipient native pancreases revealed small islets composed predominately of non-β-cells.