BD PuraMatrix peptide hydrogel, a three-dimensional cell culture model of nanofiber scaffold derived from the self-assembling peptide RADA16, has been applied to regenerative tissue repair in order to develop novel nanomedicine systems. In this study with PuraMatrix, self-assembling nanofiber scaffold (SAPNS) and Schwann cells (SCs) were isolated from human fetal sciatic nerves, cultured within SAPNS, and then transplanted into the spinal cord after injury (SCI) in rats. First, the peptide nanofiber scaffold was evaluated via scanning electron microscopy and atomic force microscopy. With phase-contrast microscopy, the appearance of representative human fetal SCs encapsulated in PuraMatrix on days 3, 5, and 7 in 12-well plates was revealed. The Schwann cells in PuraMatrix were cultured for 2 days, and the SCs had active proliferative potential. Spinal cord injury was induced by placing a 35-g weight on the dura of T9-T10 segments for 15 min, followed by in vivo treatment with SAPNS and human fetal SCs (100,000 cells/10 μl/injection) grafted into spinal cord 7 days after SCI. After treatment, the recovery of motor function was assessed periodically using the Basso, Beattie, and Bresnahan scoring system. Eight weeks after grafting, animals were perfusion fixed, and the survival of implanted cells was analyzed with antibody recognizing SCs. Immunohistochemical analysis of grafted lumber segments at 8 weeks after grafting revealed reduced asterogliosis and considerably increased infiltration of endogenous S100(+) cells into the injury site, suggesting that PuraMatrix may play an important role in the repair observed after SAPNS and human fetal SC transplantation.
(7.5 µ M ). After equilibration, the strips were relaxed by acetylcholine (10 n M to 1 m M ) in the presence or absence of indomethacin (a cyclooxygenase inhibitor; 20 µ M ). Furthermore, the relaxant responses to sodium nitroprusside (1 n M to 1 m M ), a nitric oxide (NO) donor, were investigated in both groups. NADPH-diaphorase histochemistry was used to identify NO synthase within cavernosal tissue strips of both groups.
RESULTSThe acetylcholine-dependent relaxation was significantly lower in lithium-treated rats than in controls. Although indomethacin decreased significantly the relaxant responses to acetylcholine in controls, it increased the relaxant responses in lithiumtreated rats. NADPH-diaphorase staining was greater in the chronic lithium-treated than in control preparations. Sodium nitroprusside produced similar relaxation in both groups.
CONCLUSIONChronic lithium administration can impair the endothelium-dependent relaxation of rat corpus cavernosum; NO availability might decrease after lithium administration and the cyclooxygenase pathways might have a role in this effect.
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