Regeneration across cold preserved peripheral nerve allografts

Area of Science:

• Regenerative Medicine
• Transplantation Immunology
• Nerve Repair

Background:

• Peripheral nerve injuries often require nerve grafts.
• Autografts are ideal but limited; allografts offer an alternative but face rejection.
• Effective nerve allograft storage is crucial for clinical application.

Purpose of the Study:

• To investigate the feasibility of cold storage or freeze-thawing for peripheral nerve allograft pretreatment.
• To assess the impact of these storage methods on nerve regeneration and function in a rat model.

Main Methods:

• Sciatic nerve allografts were cold-stored (3 or 5 weeks) or freeze-thawed (FT).
• Regeneration was compared to fresh auto- and allografts in an inbred rat model at 16 weeks.
• Histological and functional assessments (Sciatic Function Index, conduction velocity) were performed.

Main Results:

• Freeze-thawed (FT) allografts showed the best gross appearance, similar to autografts.
• All allograft groups exhibited inferior regeneration quality compared to autografts, with perineurial disruption and extrafascicular axons.
• While myelinated fiber numbers were comparable, allograft groups had smaller diameters and reduced conduction velocities.

Conclusions:

• Prolonged cold storage and freeze-thawing improve nerve allograft regeneration over fresh allografts but remain inferior to autografts.
• These storage techniques, combined with immunosuppression, can facilitate nerve allograft transportation and elective surgeries.
• Further research into optimizing storage and immunotherapy is warranted for clinical translation.