Growth and function of transplanted fetal rat intestine: effect of cyclosporine.

After transplantation of fetal rat small intestine in rat strains with major genetic differences, the effectiveness of cyclosporine (CyA) as an immunosuppressive agent and its effect on intestinal function were evaluated. Substrate absorption, disaccharidase activity, DNA concentration, and histologic appearance were measured and compared with those of fetal intestine transplanted in syngeneic animals. Sixteen of 20 grafts survived in the control (syngeneic) group and 14 of 20 grafts survived in the nonsyngeneic group when treated with CyA (25 mg/kg/day). None of the 10 nonsyngeneic grafts survived when no CyA was administered. Absorption of 14C-galactose in the syngeneic transplants was 0.70 +/- 0.70 mumol/cm2 intestine compared with 1.03 +/- 0.16 mumol/cm2 intestine in the nonsyngeneic transplants treated with CyA. Absorption of 14C-glycine in the respective groups was 1.63 +/- 0.22 mumol/cm2 intestine (syngeneic group) and 1.75 +/- 0.20 mumol/cm2 intestine (nonsyngeneic group treated with CyA). DNA concentration was 410 +/- 43 micrograms/mg intestine mucosa (syngeneic group) and 477 +/- 27 micrograms/mg intestine mucosa (nonsyngeneic group). There was a significant decrease in maltase and sucrase activity in the group treated with CyA but lactase activity was comparable in both groups. Evidence of mild to moderate cellular rejection was seen in only 25% of the nonsyngeneic grafts treated with CyA. When this rat fetal intestine transplant model is used, CyA appears to be an effective immunosuppressive agent and does not significantly impair growth and development of the intestine.