Delayed nerve repair increases number of caspase 3 stained Schwann cells

Caspase 3 staining in Schwann cells was investigated with immunohistochemistry, as a measure of Schwann cell apoptosis, after transection and immediate (day 0) or delayed rat sciatic nerve repair (30, 90 and 180 days post injury). Cleaved caspase 3 stained Schwann cells significantly increased at the site of lesion (SNL; median [IQR], 15.2 [7.0] %) and in the distal nerve segment (SND; 9.5 [3.6] %) 10 days after immediate repair. The number of cleaved caspase stained Schwann cells also increased significantly after delayed repair, irrespective of length of delay, at both locations (SNL: 22.0-27.1%; SND: 18.5-22.1%; p < 0.05). Some cleaved caspase 3 stained satellite cells were seen in dorsal root ganglia on the injured side, but no stained motor or sensory neurons were observed at any time-point. Delayed nerve repair is associated with more pronounced Schwann cell apoptosis which may explain impaired nerve regeneration after nerve injury and delayed repair. (C) 2009 Elsevier Ireland Ltd. All rights reserved