Micropuncture and pressure assisted Schwann cell seeding of nerve allograft.

BACKGROUND: Tissue processing to create immunotolerant nerve allograft removes neurosupportive cells. Few strategies have been described for implanting new cells into the graft to support axonal regeneration.

NEW METHOD: Micropuncture of the nerve allograft surface combined with immersion into a pressurized cell-rich solution to potentiate the introduction of viable Schwann cells (SC) into processed nerve allograft. Allografts were used to repair rodent sciatic nerve defects. At 3, 7, and 21days, grafts were harvested, stained for SCs, and analyzed using total cross sectional area (CSA) occupied by SCs to quantify SC presence.

RESULTS: At days 3 and 7, SC CSA was significantly greater for the injection group compared to all other groups. At day 21, SC CSA for the injection group (0.2252%±0.2730) was significantly greater compared to following groups: pressurized-punctured (0.0653%±0.0934), nonpressurized-nonpunctured (0.0607%±0.0709), punctured-control (0.0246%±0.0398), and nonpunctured-control (0.0126%±0.0151). A significant decrease in percent CSA occupied by SCs from day 3 to day 21 was noted in nonpressurized-punctured group (p=0.0106), pressurized-nonpunctured group (p=0.0477), and injection group (p=0.0010).

COMPARISON WITH EXISTING METHOD(S): Most studies have used small caliber hypodermic needles to inject the cells into grafts.

CONCLUSIONS: Despite a presumed decrease in cell viability over the three weeks of the study, the large initial inoculum achieved by injection technique results in higher levels of final SC seeding in acellular nerve allograft compared with bathing techniques with or without micropuncture or pressurization.