Cryopreservation of fetal rat brain tissue later used for intracerebral transplantation.

Intracerebral grafting of immature brain tissue is now widely used as a tool to study neuronal development and regeneration in the brain and spinal cord. This has stimulated the interest in methods for storage of such tissue before transplantation. In this study a method for cryopreservation of immature rat central nervous tissue is presented and discussed in relation to current cryobiological principles. The method was applied to brain tissue from 16- and 17-day-old fetal rats, including the neocortex, habenula, septum and basal forebrain, cerebellum, and retina. After storage in liquid nitrogen from 6 to 52 days the tissue was grafted into the brain of adult rats. The recipients survived for 23 to 673 days before their brains were processed by current neuroanatomical, histological methods. The presence of graft tissues was recorded and their cellular and connective organization was examined, including their exchange of nerve connections with the host brain. The results obtained were comparable with results from other studies where the same tissues were grafted immediately after removal from the donor, and a study of cryopreservation of developing hippocampal tissue. We conclude that cryopreservation is a reliable method for storage of immature neural tissue later to be used for intracerebral grafting.