The use of autograft resulted in better motor recovery than did the use of allograft or a collagen conduit for a short nerve gap in rats. A longer evaluation time of sixteen weeks after segmental nerve injuries in rats would be beneficial as more substantial muscle recovery was seen at that time.
Isometric tetanic muscle force has been described in a rat model to evaluate motor recovery in a segmental sciatic nerve defect reconstructions. However, to test longer nerve defects, an alternative and larger animal model is necessary. The purpose of this study is to describe and validate a technique for isometric force measurement of the tibialis anterior (TA) muscle in New Zealand rabbits. Muscle preload and electrical stimulation parameters were optimized to obtain the highest tetanic contraction bilaterally in 10 animals. Electrophysiology, muscle weight, peroneal nerve length, and histomorphometry were also analyzed. Only the peroneal nerve length and the ratio of highest muscle force/muscle weight demonstrated the equivalence between the sides. A small variability of TA muscle force and TA muscle weight was observed between the sides suggesting dominance. Optimization of electrical stimulation and preload as well as the use of correct anesthesia were fundamental to acquire the highest muscle force.
ABSTRACT:We have previously shown experimental transplantation of living allogeneic bone to be feasible without long-term immunosuppression by development of a recipient-derived neoangiogenic circulation within bone. In this study, we examine the role of angiogenic cytokine delivery with biodegradable microspheres to enhance this process. Microsurgical femoral allotransplantation was performed from Dark Agouti to Piebald Virol Glaxo rats. Poly(D,L-lactide-co-glycolide) microspheres loaded with buffer, basic fibroblast growth factor (FGF), vascular endothelial growth factor (VEGF), or both, were inserted intramedullarly along with a recipient-derived arteriovenous (a/v) bundle. FK-506 was administered daily for 14 days, then discontinued. At 28 days, bone blood flow was measured using hydrogen washout. Microangiography, histologic, and histomorphometric analyses were performed. Capillary density was greater in the FGFþVEGF group (35.1%) than control (13.9%) (p < 0.05), and a linear trend was found from control, FGF, VEGF, to FGFþVEGF (p < 0.005). Bone formation rates were greater with VEGF (p < 0.01) and FGFþVEGF (p < 0.05). VEGF or FGF alone increased blood flow more than when combined. Histology rejection grading was low in all grafts. Local administration of vascular and fibroblast growth factors augments angiogenesis, bone formation, and bone blood flow from implanted blood vessels of donor origin in vascularized bone allografts after removal of immunosuppression. ß
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