Neonatal Dorsal Root Ganglia Stem Cells Form Oligodendrocytes After Transplantation To The Cerebrospinal Fluid Surrounding Cauda Equina Lesions

BackgroundNeural stem cells (NSCs) possess the ability for self-renewal and the capacity to formneurons and glia. Numerous studies attempt to perform stem cell transplantation as a mean tomediate recovery of the brain and spinal cord following injury. A simultaneous compressionof several, eventually all lumbosacral spinal nerve roots may lead to the development of acomplex clinical entity called cauda equina syndrome (CES). The failure of axons toregenerate results in severe and often permanent functional impairments. The results ofrecovery of bladder function are, in general, felt to be poor. At present there is no effectivetreatment for CES in clinic. To our knowledge, the NSCs’ fate after transplantation to thecerebrospinal fluid around lesioned cauda equina has not been reported before.In our study, we try to use NSCs to repair damaged cauda equina in a rat model of lumbarspinal canal stenosis (LCS). We adopted neonate day2rat DRG as the source of NSCs. Weinvestigated neonate DRG-NSCs’ multipotency in vitro. Furthermore, these stem cells weretransplanted in the cerebrospinal fluid around lesioned cauda equina through subarachnoidmicroinjection to investigate neonate DRG-NSCs’ survival, differentiation and functionalsignificance in vivo.ObjectiveThe purpose of this study was to characterize the fate of neonatal dorsal root ganglia(DRG) stem cells following transplantation into the cerebrospinal fluid surrounding caudaequina lesions.MethodsNeonatal day2rat DRG were used as the source of neural stem cells (NSCs). Thirty-six6-week-old male SD rats were anesthetized with10%chloral hydrate. Laminectomies wereperformed at L4, and a piece of silicone (10-mm long,1-mm wide,1-mm thick) was placedunder the laminae of the fifth and sixth lumbar vertebrae (n=24). Lumbar spinal canalstenosis (LCS) model rats were divided randomly into2subgroups: the NSCs group (n=12)and the control group (n=12). In the sham-operated group, laminectomies were performed at L4(n=12). Seven days after surgery, rats from the NSCs group were injected with greenfluorophore [lenti-(e)GFP]-NSCs. Approximately800,000GFP-NSCs were injected into eachrat from the NSCs group by subarachnoid microinjection; control-group rats were injectedwith the same volume of phosphate buffered saline (PBS) in the same manner. Differentiationof DRG-NSCs in vitro and in vivo was assessed by immunohistochemistry. The tail-flick testwas performed to assess whether transplantation of NSCs improved sensory function.ResultsThe neonatal DRG-NSCs used in the in vitro experiment mostly differentiated intooligodendrocytes after7days without growth factors, and1week after transplantation, mostGFP-NSCs differentiated into O4+oligodendrocytes; no astrocytes (GFAP+) or neurons(βIII-tubulin+) were detected. No significant differences in the tail-flick test results weredetected at any time point between the NSCs group and the control group.ConclusionNeonatal DRG-NSCs differentiated into oligodendrocytes in vitro. DRG-NSCs cansurvive and differentiate into oligodendrocytes after transplantation into the cerebrospinalfluid. The recovery of sensory function was not significantly improved in rats withtransplanted NSCs.