Abstract：Objective To detect the myelinating role of olfactory ensheathing cells (OECs in the contused spinal cord and their impact on remyelination.Methods The rats were subjected to spinal cord injury at T10(10 g ×25 mm) using a NYU-Ⅱ impactor.One week later,the rats were transplanted with green fluorescence protein (GFP)-OECs (OECs group) or an equal volume of Dulbecco' s modification of Eagle's medium (DMEM) (control group) at epicenter of the injury as well as its rostral and caudal sites.Six weeks after transplantation,the spinal cords were removed for frozen section.Myelin basic protein (MBP),protein zero (P0),and S100 protein (S100) were determined with qualitative and semi-quantitative immunocytochemical assay.Moreover,plastic embedded semithin and ultrathin sections were prepared for qualitative and semi-quantitative examination under light microscopy and electroscopic study of myelin sheath ultrastructure.Results In OECs group,the nerve fibers labeled with S100,MBP,and PO were extended from the normal tissues to the injured region and even grew through the region with space consuming of 12.3％,11.6％,and 9.3％ respectively.Moreover,there were no statistical differences regarding the number of fibers labeled by the three proteins,but all were significantly larger than that in control group (2.89％,P ＜ 0.01).Number of myelinated nerve fibers in injured regions on hemithin sections was increased significantly to 354.67 ± 59.00 in OECs group,with significant difference compared with 167.33 ± 42.16 in control group (P ＜ 0.01).The regenerated myelin sheaths in OECs group were smaller and thicker than those in control group.Conclusions OECs can accelerate regeneration of myelinated nerve fibers.Additionally,some OECs form myelin sheaths themselves,but the sheath structures are relatively thinner.
