| [Objective]In present study, based on a great deal of reports and effective strategies of clinical therapy of SCI, we used different supporting cells (SC and OEC) to combined with different stem cells like neural stem cells(NSC), mensenchymal stem cells(BMSC) and heomopoietic stem cells(HSC) to seek for the optimal method which promotes SCI restoration, by means of co-transplantation of different supporting cells and different stem cells based on the theory that supporting cells can play a role in bridge grafting and NTF secretion and stem cells can differentiate into target cells so as to replace of host lost neurons. Our objective is to get the most effective methods for the SCI therapy by cellular coordination. Then we ask the possible mechnism.[Method]Three Stem cells consisting of neural stem cells(NSC), mensenchymal stem cells(BMSC) and heomopoietic stem cells(HSC) as well as two support cells including olfactory ensheathing cell (OEC) , and Schwann cells (SC) were as seedcells to be impanted into spinal cord following injury. The the most Optimal strategyof stem cell transplantation into transected spinal cord, and the role of PDGF were investigated by using cells culture, Immunohistochemistry (IHC), Western-blot, Reverse Transcription polymerase Chain Reaction (RT-PCR), RNA intererence and antibody block method, and Behavioral test as well as electrophysiological test. [Result]1. Aafter spinal cord was transected, rats showed flaccid paralysis in hindlimbs immediately, indicating that the transection of the cord was completely transected. Moreover, cell transplantation results in spontaneous, howbeit incomplete, recovery of the hindlimb locomotor functions after spinal cord transection (SCT). The BBB score of cell transplantaion group was significant higher than operation group at all of the different time points (P<0.05), especially from 2 wekks to 6 month. Of 11 combination strategy, we found that NSC and OEC co-transplantation could provide the most significant amelioration for the recovery of rats behavior following SCT. This effect was confirmed from the test employed by monkey SCI model. The mechanism for this improvement is involved in regulation of various NTF in host spinal cord. Involved factors by RT-PCR including in brain derived neurotrophic factor (BDNF), Cilliary neurotrophic factor(CNTF), Isulin-like growth factor, (IGF), Fibroblast growth factor(FGF), Glia derived neurotrophic factor(GDNF), etc.2. The optimal strategy of stem cell transplantation into transected spinal cord was test in primate monkey so as to provide some evidences fo humanbeing usage.3. Based on the results from previous data that quantitative analysis demonstrated that the Pletlet derived neurotrophic factors (PDGF) was downregulated in the spinal cord following NSC and OEC transplantaion (P<0.05). This indicated that PDGF maybe a vital molecules that exert negtive effect in improving neuroplasticity. This push us to determine the role of PDGF in the traumatic spinal cord. Despite PDGF-BB plays a crucial role in regulating neuronal survival and cell differentiation during embryonic development and in the adulthood. The roles it plays in astrogliosis and the formation of scar tissue after spinal cord transection (SCT), however, has not been studied. Thereforem This part we explore the roles of PDGF-BB in regulating astrogliosis at molecular level and to correlate them with axonal regeneration and sprouting and functional recovery. As early as 1 day after SCT and continuing through 28days, PDGF-BB protein and mRNA were up-regulated in the injured spinal cord. PDGF-BB immunoreactive products were detected in both neurons and astrocytes, at 1 day after SCT and these gradually increased in astrocytes till 28days. This was paralleled by scar tissue formation, and upregulation of signal transducer and activator of transcription 3 (STAT-3), all of which are the downstream signaling molecules of PDGF-BB. Blocking of and interfering with the activity of PDGF-BB with PDGB-BB-antibody and siRNA (to spell out in full) respectively resulted in significant (i) down-regulation in the downstream signaling molecules of PDGF-BB; (ii) reduction in astrogliosis and scar tissue formation; (iii) reduction of STAT-3; and (iii) improvements in hindlimb locomotor and sensory functions.Taken together, our data suggest that OEC and NSC transplantaion could be as a optimal strategy into damaged spinal cord for future clinic usage, and the possible mechnism involved in several cytokines regulation. Of them, PDGF play a crucial role in neuroplasticity following spinal cord injury and cell transplantion. |
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