Analysis of fibrogenic processes in denervated tissues of spinal cord injury patients

To test the hypothesis that altered collagen metabolism is a contributing factor in the apparent delayed wound healing in denervated regions of spinal cord injury (SCI) patients, a tissue implant (PVA) was used to directly measure collagen deposition. Sterile PVA implants were placed subcutaneously in the inner aspect of the upper arm above the cord injury (innervated) and in the inner aspect of the upper leg below the cord injury (denervated) of 20 spinal cord injury patients and compared to eight healthy volunteers. On day 14, the implants were removed and analyzed histologically by trichrome stain and biochemically for hydroxyproline as a measure of collagen deposition. No remarkable histologic differences were observed in the sponge material removed from the upper regions compared to the lower denervated regions of the spinal cord injury patients. Sponges from both areas were infiltrated with fibroblasts containing well-developed rough endoplasmic reticulum and large quantities of trichrome-positive collagen. Likewise, upper and lower histology of controls was identical and nondistinguishable from the corresponding sections obtained from the spinal cord injury patients. Quantitation of the hydroxyproline in the arms of the spinal cord injury patients (n = 20) showed 4.3 +/- 0.7 nmol hydroxyproline per milligram of sponge compared to 4.1 +/- 0.4 nmol/mg in the denervated regions of the lower limb. The hydroxyproline content in the arms of control volunteers was 5.2 +/- 0.7 nmol/mg compared to 3.9 +/- 0.8 nmol/mg in the leg (n = 8). These observations suggest that fibrogenic processes in denervated regions are not reduced significantly compared to innervated regions.