Viability of nerve grafts preserved in different storage medium: ultrastructural features

ABSTRACT

We investigated the ultrastructural organization of transplanted autologous grafts after storage in two different solutions. Male Wistar rats were divided into groups to obtain normal tibial nerves, freshly transplanted nerves, and nerves stored in Wisconsin/Belzer or Collins solution for 24 or 72 hours at 4 °C and transplanted (W1, W3, C1, C3). After storage or transplantation, the specimens were processed for ultrastructural analysis. All grafts showed alterations in collagen fiber organization in the endoneurial space compared to normal nerves. These fibers were more loosely organized among nerve fibers, a finding that was significantly more marked in group C3 compared to groups W1 and W3. Important alterations were also observed in the myelin sheath structure of grafts stored in the two media. These changes were characterized by separation of the lipid lamellae, clearly visible in larger diameter nerve fibers. These findings were more marked and frequent in the C1 and C3 groups compared to the W1 and W3 groups. Ultrastructural analysis showed better preservation of Schwann cells and other elements that support axonal regeneration for grafts stored in Wisconsin/Belzer solution. These results support ongoing studies for the formulation of storage solutions that permit the creation of nerve banks for heterologous transplantation.