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 transplanted into it, we have performed experiments that suggest some effect of hepatic cells for islet tolerance. We have studied 6 groups of Wistar rats made diabetic with streptozotocin and transplanted in sham conditions and with a mixture of islets and hepatic cells (allo-co-transplantation) in several conditions, all of them via the portal vein, and observed them over 30 days. Groups were as follows: Group A had a sham transplantation with saline. Group B was transplanted with hepatic cells alone. Group C was transplanted 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 after co-culture of islets and hepatic cells for 24 hours. Results show reversion of diabetes in group D for 4-5 days, and thereafter, a fall of blood glucose during the period observed. The effect was less marked in group F after 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 results 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 clarify if this effect can be related to some hepatic cell subpopulation; also if the effect is a membrane one, cell-to-cell contact, or through some secreted product.