Influence of collagen and laminin gels concentration on nerve regeneration after resection and tube repair

In order to assess the usefulness of collagen and laminin gels prefilling nerve chambers to enhance nerve regeneration, we compared reinnervation of target organs after sciatic nerve resection leaving gaps of 4 or 6 mm followed by repair with silicone tubes in different groups of mice. Tubes were prefilled with saline solution, collagen gels, or laminin- containing gels at different concentrations. Functional reinnervation was assessed by noninvasive methods to quantitate recovery of sweating, nociceptive, sensory, and motor functions in the hindpaw repeatedly during 4- 5 months postoperation. The increase in gap length between nerve stumps delayed the beginning and reduced the degree of functional recovery achieved. Reinnervation started earlier and achieved slightly higher levels with collagen gel diluted at 1.28 mg/ml than with more concentrated (1.92 and 2.56 mg/ml) collagen gels and with saline-prefilled tubes bridging a 4-mm gap. Recovery was also better with diluted (4 mg/ml) than with concentrated (12 mg/ml) laminin-containing gel, although lower than with collagen gels and saline. By prefilling silicone tubes bridging a 6-mm gap, a length considered limiting for regeneration in the mouse sciatic nerve, with diluted collagen or laminin gels, both matrices allowed for higher levels of recovery and for successful regeneration in a higher proportion of mice than saline solution. The laminin gel performed slightly better than the collagen gel.