IMPROVED CRYOPRESERVATIVE MEDIUM SUITABLE FOR THE FREEZE-STORAGE AND TRANSPLANTATION OF FETAL NEURAL TISSUES

Techniques to maintain viable fetal neural tissue might be an importan t tool for a successful neural transplantation by giving enough time f or preparation, storage, and transportation of donor tissue. In the pr esent study, we examined the effect of freeze-storage (cryopreservatio n) for 7 days at liquid nitrogen temperature on the survivability of i ntraventricular rat fetal mesencephalic grafts (gestational day 15) wh en using 10% dimethyl sulfoxide (DMSO), 0.1% methylcellulose, or 10% D MSO with additional 0.1% methylcellulose (m-DMSO) as a cryoprotective agent. As a control group, the survivability of grafts transplanted im mediately after dissection was examined. The volume of grafts treated with m-DMSO was 3 times as large as that of grafts treated with 10% DM SO alone. While the number of surviving neurons in 10% DMSO-treated tr ansplants decreased down to 15% of the control value, there was no sta tistically significant difference in the number of surviving neurons b etween the m-DMSO treated group and control group. In the group treate d with m-DMSO, there were a lot of well developed tyrosine hydroxylase positive neurons and fibers in the graft, and a few reactive astrocyt es were observed only in the peripheral region of the grafts. In the g roup treated with 0.1% methylcellulose alone, no graft survival was ob served in any of the animals. We conclude that the addition of methylc ellulose to the commonly used cryoprotective agent (DMSO) is beneficia l for the freeze-storage of fetal neural tissue.