Intraspinal cord graft of autologous activated Schwann cells efficiently promotes axonal regeneration and functional recovery after rat's spinal cord injury.

Basic research in spinal cord injury (SCI) has made great strides in recent years, and some new insights and strategies have been applied in promoting effective axonal regrowth and sprouting. However, a relatively safe and efficient transplantation technique remains undetermined. This study, therefore, was aimed to address a question of how to graft Schwann cells to achieve the best possible therapeutic effects. To clarify the issue, the rats were subjected to spinal cord injury at T10. Autologous activated Schwann cells (AASCs) were obtained by prior ligation of saphenous nerve and subsequently isolated and purified in vitro and then grafted into spinal cord-injured rats via three different routes (group I: intravenous, group II: intrathecal and group III: intraspinal cord). Neurologic function was serially evaluated by Basso, Beattie, Bresnahan locomotor rating scale and footprint analysis. We also evaluated the migration of the transplanted cells at 2 weeks after transplantation. Using biotinylated dextran amine (BDA) anterograde tracing, we demonstrated that more regenerative axons of corticospinal tract (CST) surrounding the injured cavity in group III than those in the other two groups, and we also confirmed it further by quantitative analysis. The microenvironment surrounding the injured spinal cord has been improved to the greatest extent in group III, as determined by immunohistological staining. Relatively complete myelin sheaths and more neurofilaments in axons were found in groups II and III than those in group I under electron microscopy. The results showed that intraspinal cord injection of AASCs promoted recovery of hindlimb locomotor function of injured rats more efficiently than the other grafting routes. In addition, intact myelin sheaths and sufficient neurofilaments in axons were not adequate for full functional recovery after SCI, suggesting that reestablishment of normal synaptic connection is indispensable. The findings in this study strongly suggest that transplantation of AASCs directly into the spinal cord may be one of the promising candidates for potential scaffold for injured spinal cord, and such strategy of transplantation of AASCs could be hopeful to treat patients with SCI.

Regeneration of spinal cord with cell and gene therapy.

OBJECTIVE: Transplantation of fetal spinal cord cells (FSCC) can promote regeneration of injured spinal cord, while Schwann cells (SC) and some growth factors have a similar effect. However, the synergistic effects and optimal combination of these modalities have not yet been evaluated. In the current study, the efficiency of cell therapy of FSCC and/or SC, with/without growth factors (nerve growth factor [NGF] and brain-derived neurotrophic factor [BDNF]) was examined, with the aim of establishing an optimized protocol for spinal cord injury. METHODS: One hundred and twenty adult rats were randomly divided into six groups with 20 rats in each group. One week after the thoracic spinal cord injury model had been created, the rats were treated with different therapeutic modalities: Dulbecco's modified Eagles medium (DMEM) in Group I, FSCC in Group II, FSCC plus SC in Group III, FSCC plus SC over-expressing NGF in Group IV, FSCC plus SC over-expressing BDNF in Group V, and FSCC plus SC over-expressing both NGF and BDNF in Group VI. Subsequently, the rats were subjected to behavioral tests once a week after injury, while histology, immunohistochemistry and electron microscopy were performed at one and three month post-operation. RESULTS: Both SC and FSCC promoted regeneration of spinal cord injury when used separately, while a combination of the two types of cell resulted in better recovery than either alone. Both growth factors (NGF and BDNF) enhanced the outcomes of cell therapy, while synergistic effects meant that a combination of each individual component (group VI) achieved the best results according to locomotion scale, histology and immunoreactivity in the injured cords. CONCLUSION: SC, NGF and BDNF can enhance the outcome of FSCC therapy, while the combination of FSC with SC, NGF and BDNF is possibly the optimal protocol for clinical treatment of acute spinal cord injury.

Treatment of spinal cord injury with co-grafts of genetically modified Schwann cells and fetal spinal cord cell suspension in the rat.

Fetal spinal cord cells, Schwann cells and neurotrophins all have the capacity to promote repair of injured spinal cord in animal models. To explore the possibility of using these approaches to treat clinical patients, we have examined whether a combination of these protocols produces functional and anatomical improvement. The spinal cords of adult rats (n=16) were injured with a modified New York University (NYU) device (10 gram.5cm). One week after injury, the injured cords were injected with Dulbecco-modified Eagles Medium (DMEM, control group), or fetal spinal cord cell suspension (FSCS) plus nerve growth factor (NGF) gene-modified Schwann cells (SC) and brain-derived neurotrophic factor (BDNF) gene-modified SC (treatment group). The rats were subjected to BBB (Basso, Beattie, Bresnahan, Exp. Neurol. 139:244, 1996) behavioral tests. Anterograde tracing of corticospinal tract was performed before sacrifice 3 months after the treatment. The results showed that the combination treatment elicited a robust growth of corticospinal axons within and beyond the injury site. A dramatic functional recovery in the treatment group was observed compared with the control group. We conclude that the combination of FSCS with genetically modified Schwann cells over-expressing NGF and BDNF was an effective protocol for the treatment of severe spinal cord injury.

[Synapses developing process of neuroblasts after acute spinal cord transplantation in rats].

OBJECTIVE: To explore the potential possibility of synaptic connection and 3D adhesion between fetal spinal cord cell suspension (FSCS) and host, and to observe the synapses developing process of FSCS transplantation. METHODS: Spinal cord injury model produced in 42 Wistar rats on T7 by use of modified Allen's impact method (10 g x 5 cm); 3 days after injury, 20 microliters FSCS with a density of 1 x 10(5)/microliter prepared from E14 rat were injected into the epicenter of the traumatized cavity. Animals were sacrificed after 2, 4, 6, 8, 10 and 12 weeks of transplantation, the graft survival, its differentiation and integration with the host were observed by light and electronmicroscopic study as well as immunohistochemical assay (NF, GFAP, CGRP, 5-HT). RESULTS: In the transplantation area, the neuroblasts stretched out the terminal endings 4 weeks after implantation, followed by the presenting of the pre- and postsynaptic membrane. After 8 weeks, the dense or developed projections were observed in the pre- and postsynaptic membrane; the synaptic cleft filled with the high electron dense substance. All the spherical clear vesicles, granular vesicles, elliptical vesicles and flattened-f type vesicles were seen under the electronmicroscope. After 10 weeks, the axosomatic, dendrosomatic, dendro-dendritic, axo-axonic, dendro-axonic synapses coexisted. Light microscopy showed that the graft cell grew gradually. Immunohistochemical assay showed that NF, 5-HT, CGRP and GFAP positive fibers were in the graft. Synapses, gliafibers and blood brain barrier integrated each other. CONCLUSION: (1) The transplanted FSCS can develop mature synapses with miscellaneous synaptic vesicles in the acute injured spinal cord, host injury cavity wall may induce the FSCS into 3D adhesion. (2) Co-existence of different type of synapse and the immunohistochemistry findings indicate the possibility of synaptic connection between FSCS and host.