Optimization of the Missouri Osteochondral Preservation System for the storage of peripheral nerve allografts

Peripheral nerve reconstruction for large-gap injuries remains limited by the shortcomings of autografts and decellularized allografts, which rarely achieve full recovery and carry donor site morbidity. This study investigated whether the Missouri Osteochondral Preservation System (MOPS) could be optimized for peripheral nerve allograft preservation by supplementing it with methylcobalamin (MOPS-N-B12) or glial-derived neurotrophic factor (MOPS-N-GDNF). Fifty rat sciatic nerves were harvested, stored in one of three solutions (MOPS, MOPS-N-B12, MOPS-N-GDNF), and analyzed after 30, 60, or 90 days. Outcomes included compound action potentials (CAPs), Schwann cell viable cell density (VCD), and histopathology. CAPs were evoked in all grafts at 30 days, and in all MOPS-N-B12 and MOPS-N-GDNF grafts at 60 days, compared to only 60% of MOPS grafts. At 90 days, 80% of MOPS-N-B12 and MOPS-N-GDNF grafts retained CAPs, vs. 40% for MOPS. VCD was maintained across groups at 30 days, but MOPS-N-B12 showed significantly higher VCD at 60 and 90 days. Notably, grafts with VCD <100 cells/mm² failed to evoke CAPs. Histopathology severity scores increased over time for all groups, though MOPS-N-B12 consistently had lower scores at 60 and 90 days, reflecting reduced Schwann cell death, axonal degeneration, and myelin disruption. These findings suggest that MOPS-N-B12 provides superior preservation of Schwann cell viability, myelin integrity, and electrical conduction compared to standard MOPS or MOPS-N-GDNF. Importantly, viable nerve allografts were maintained for up to 90 days at room temperature, supporting the feasibility of shelf-stable, off-the-shelf viable nerve allografts for clinical use in peripheral nerve reconstruction.