DNA replication in mouse pancreatic islets transplanted subcapsularly into the kidney or intraportally into the liver. Influence of unilateral nephrectomy or partial hepatectomy.

3H-thymidine incorporation into DNA (estimated as the autoradiographic labeling index [LI]) was used as an index of DNA replication in syngeneic mouse islets grafted into the kidney or liver 4 weeks before unilateral nephrectomy (UN) or partial hepatectomy (PH). Removal of one kidney resulted in a significantly increased growth of the remaining islet-bearing kidney initiated during the first week after surgery. Seven days after 40% hepatectomy the remaining liver mass corresponded to 91% of that of sham-operated (SO) mice. The induced kidney and liver growth in mice subjected to UN or PH was correlated with an increased LI, which was similar in both organs (3.5 times the LI in kidneys and livers of SO-controls). Pancreatic islets implanted into the organs undergoing compensatory growth also had higher LI values that were less pronounced as compared with the LI measured in the parenchymal cells of the kidney or the liver after UN or PH, respectively. In contrast to the grafted islets, no changes in the LI of the endogenous pancreatic islets were found. To evaluate possible systemic effects of the induced growth stimulation, the livers of UN-mice and the kidneys of PH-mice were investigated. No change in the LI of the liver tissue was observed 3 and 6 days after UN, whereas the kidney cortex showed a significantly increased LI7 days after PH. It is concluded that when exposed to a local, non-specific growth stimulation in vivo pancreatic islets prepared from adult donors are able to respond with an enhanced replicatory activity. The effect is, however, only present when the islets are located in the organs in which growth has been induced.