Physiology of peripheral nerve graft incorporation

The degree of cell survival and the rate and extent of cellular migration was studied in fresh- and freeze-killed nerve grafts using an animal model with isogeneic nerve grafts performed between inbred rats. Nerve isografts 1.4 cm in length were used to bridge a 1.0 cm gap created in recipient animals. Vital fluorescent staining was used to monitor cell viability and to track cell migration between the nerve graft and the recipient host's nerve endings. The fresh nerve grafts maintained their fluorescent label, indicating that these grafts maintained their viability. The freeze-killed grafts had significantly lower cell survival, as determined by percent area of fluorescence, both 14 and 25 days after nerve grafting. The freeze-killed grafts also demonstrated a lower percentage of incorporation of labeled host cells from the proximal host nerve ending. Since the fresh nerve grafts maintained their viability, even though they were performed as nonvascularized grafts, free vascularized nerve grafts may not be necessary if a good vascular bed is present.