Influence of hepatic cells on allogeneic islet transplantation in rats without immunosuppressive drugs

With the hypothesis of a possible helpful effect of the liver on islets tra nsplanted into it, we have performed experiments that suggest some effect o f hepatic cells for islet tolerance. We have studied 6 groups of Wistar rat s made diabetic with streptozotocin and transplanted in sham conditions and with a mixture of islets and hepatic cells (allo-co-transplantation) in se veral conditions, all of them via the portal vein, and observed them over 3 0 days. Groups were as follows: Group A had a sham transplantation with sal ine. Group B was transplanted with hepatic cells alone. Group C was transpl anted with islets alone without hepatic cells. Group D was co-transplanted with cultured islets and fresh hepatic cells (ratio 1:100), Group E was as group D with a ratio of 1:200. Group F also had co-transplantation, but aft er co-culture of islets and hepatic cells for 24 hours. Results show revers ion of diabetes in group D for 4-5 days, and thereafter, a fall of blood gl ucose during the period observed. The effect was less marked in group F aft er co-culture of islets and hepatic cells, Paradoxically, when the ratio of islets and hepatic cell were 1:200, the results were not so good. These re sults suggest that hepatic cells have some helpful effect on islets when co transplanted in the liver via the portal vein. More studies are needed to c larify if this effect can be related to some hepatic cell subpopulation; al so if the effect is a membrane one, cell-to-cell contact, or through some s ecreted product.