ABSTRACT
Even though autogenous nerve grafts are used frequently, there is little information
concerning cell survival rates and migration patterns, following peripheral nerve
grafting. Labeling techniques with a vital fluorescent stain (PKH-26, Zynaxis Cell
Science, Malvern, PA) allow cell migrations from both the nerve graft and host nerve
to be tracked for up to 45 days from the time of nerve transplantation. With this
labeling technique, two phases of nerve graft incorporation were identified, early
and late, in an animal model using inbred Lewis and Brown-Norway rats. In genetically
identical Lewis rats, isografts were performed as a means of modeling the autografts
used clinically. At approximately 3 days after isogeneic transplantation, with the
proximal host nerve end labeled, there was an early migration of host cells from the
proximal nerve end into the epineural tissue of the nerve graft. At 25 days, a late
phase was evident, with fluorescent labeling of host cells into the perineural and
endoneural tissues. When the nerve grafts were labeled, the label persisted for up
to 45 days, indicating viability of the graft. Cells migrated from the labeled nerve
graft into the distal host nerve segment. Cellular migration from peripheral nerve
tissue, following allograft transplantation, was initially similar to the isograft
studies. But after 25 days, with the proximal host nerve end labeled, a significant
decrease in the labeled host cells migrating into the graft was noted (p < 0.05). By 45 days after allograft transplantation with the nerve graft labeled,
there was a significant decrease in the percentage of tissue with the fluorescent
label, indicating a loss in viable cells within the graft (p < 0.05). Furthermore, the migration of labeled cells from the graft into the distal
host nerve end was significantly decreased.
Clinical Relevance. Autogenous nerve grafts function as viable tissue grafts, and
techniques to preserve this viability during surgery should be optimized. Allografts
are incorporated by integration of host nerve cells until rejection occurs. This labeling
technique with PKH-26 may provide a method of quantifying the efficacy of techniques
to delay or decrease allograft rejection through immunosuppression or tissue typing.
