Effects of Fetal Spinal Cord Transplants on Injured Rat Spinal Cord

OBJECTIVE: Previous studies have demonstrated that axon regeneration or remyelination after spinal cord injury occurs when provided with a suitable substratum such as fetal spinal cord (FSC). We carry out this study to determine whether FSC transplants can reduce the glial scar at the interface between host and graft. METHODS: Hemisectioned spinal cord injury was made by aspiration at T3 or T4 spinal cord level in rat. Cell suspension of E-14 FSC was introduced into the injured cavity contaning glial scar tissue. To indentify the transplanted cells from host tissue, FSC cells were labeled with DiI. Rats were sacrificed at 1, 2, 3, and 8 weeks after transplanation and spinal cord was undergone serial sections for immunocytochemistry and histological observation. The observation by electron microscope was carried out too. RESULTS: We could observe that the FSC transplants survived in host spinal cord and generally occupied most of the neuron-depleted area. Examination of serial sections through the graft-host interface which had been immunoreacted for glial fibrillary acidic protein demonstrated that the glial scar was no longer a continuous wall separating the graft and host tissues at eight weeks after injury. We could observe oligodendrocyte and the reformed myelin at the interface by electron microscope. CONCLUSION: The fetal spinal cord transplant can reduce an established glial scar or restrict the reformation of a scar following surgical manipulation, and that the FSC transplant can promote remyelination.

Early Detection of Hyperacute Cerebral Infarction in Dogs: Comparison of Unenhanced CT, Diffusion-weighted,Spin-echo T2 - weighted, and Fast FLAIR MR Imaging

PURPOSE: This study was performed in order to compare unenhanced CT with diffusion-weighted, T2-weight-ed,and fast FLAIR MR imaging in the detection of hyperacute cerebral ischema induced in a dog and to deter-mine whichmodality first detected cerebral ischemia. MATERIALS AND METHODS: Experimental cerebral infarction was induced bythe occlusion of intracerebral arter-ies using embolic materials (polyvinyl-alcohol, 300 -6 00 micro) introducedthrough a microcatheter into the internal carotid artery of five dogs weighing 12 -20 kg. Serial CT and MR imageswere obtained at one hour intervals from one to five hours after occlusion, and were analyzed independently by tworadiologists. We assessed changes in attenuation, as seen on unenhanced CT and the signal intensity of the lesionon each MR image, and measured the contrast-to-noise ratio (CNR) of the lesions. RESULTS: Ischemic lesions weredetected on unenhanced CT 1 -3 hours after occlusion of cerebral arteries. In all dogs, the lesions were detectedearliest on diffusion-weighted images obtained at 1 hour. They were detect-ed on T2-weighted images at 3 -5 hoursand on fast FLAIR images of 2 -5 hours. The CNR of ischemic lesions increased gradually during the 5-hour period.It was highest on diffusion-weighted images, while on unen-hanced CT, T2-weighted, and fast FLAIR images it wassimilar. CONCLUSION: Hyperacute ischemic lesions were detected earliest on diffusion-weighted images, and earlieron unenhanced CT than on fast FLAIR or T2-weighted MR image.