Feasibility of Diffusion Tensor Imaging for Assessing Functional Recovery in Rats with Olfactory Ensheathing Cell Transplantation After Contusive Spinal Cord Injury (SCI)

Considering the Cellular Composition of Olfactory Ensheathing Cell Transplants for Spinal Cord Injury Repair: A Review of the Literature

Olfactory ensheathing cells (OECs) are specialized glia cells of the olfactory system that support the continual regeneration of olfactory neurons throughout adulthood. Owing to their pro-regenerative properties, OECs have been transplanted in animal models of spinal cord injuries (SCI) and trialed in clinical studies on SCI patients. Although these studies have provided convincing evidence to support the continued development of OEC transplantation as a treatment option for the repair of SCI, discrepancies in the reported outcome has shown that OEC transplantation requires further improvement. Much of the variability in the reparative potential of OEC transplants is due to the variations in the cell composition of transplants between studies. As a result, the optimal cell preparation is currently a subject of debate. Here we review, the characterization as well as the effect of the cell composition of olfactory cell transplantation on therapeutic outcome in SCI. Firstly, we summarize and review the cell composition of olfactory cell preparations across the different species studied prior to transplantation. Since the purity of cells in olfactory transplants might affect the study outcome we also examine the effect of the proportions of OECs and the different cell types identified in the transplant on neuroregeneration. Finally, we consider the effect of the yield of cells on neuroregeneration by assessing the cell dose of transplants on therapeutic outcome.

Biological effects different diameters of Tussah silk fibroin nanofibers on olfactory ensheathing cells

Transplantation of olfactory ensheathing cells (OECs) has potential for treating spinal cord and brain injury. However, they are void of an extracellular matrix to support cell growth and migration. Engineering of tissue to mimic the extracellular matrix is a potential solution for neural repair. Tussah silk fibroin (TSF) has good biocompatibility and an Arg-Gly-Asp tripeptide sequence. A small number of studies have assessed the effect of the diameter of TSF nanofibers on cell adhesion, growth and migration. In the present study, TSF nanofibers with a diameter of 400 and 1,200 nm were prepared using electrospinning technology; these were then used as scaffolds for OECs. The structure and morphology of the TSF nanofibers were characterized by scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy. An inverted-phase contrast microscope and SEM were used to observe the morphology of OECs on the TSF nanofibers. The effect on the adhesion of the cells was observed following crystal violet staining. The phenotype of the cells and the maximum axon length on the scaffolds were evaluated by immunostaining for nerve growth factor receptor p75. Cell proliferation and viability were assessed by an MTT assay and a Live/Dead reagent kit. The migration efficiency of OECs was observed using live-cell microscopy. The results indicated that a 400-nm TSF fiber scaffold was more conducive to OEC adhesion, growth and migration compared with a 1,200-nm TSF scaffold. The phenotype of the OECs was normal, and no difference in OEC phenotype was observe when comparing those on TSF nanofibers to those on PLL. The present study may provide guidance regarding the preparation of tissue-engineered materials for neural repair.

Transplantation of Recombinant Vascular Endothelial Growth Factor (VEGF)189-Neural Stem Cells Downregulates Transient Receptor Potential Vanilloid 1 (TRPV1) and Improves Motor Outcome in Spinal Cord Injury

Background

Spinal cord injury (SCI) causes a rapid loss of motor neurons, leading to weakness and paralysis. Transplantation of neural stem cells is known to restore the neuronal activity but is inefficient due to limited regenerative capability and low rate of survival. There has been an emphasis on the use of growth factors along with neural stem cells (NSCs) to enhance the neuronal recovery. Transplantation of recombinant NSCs with vascular endothelial growth factor (VEGF) might promote neuronal repair. This effect might be attributed to the reduced transient receptor potential vanilloid 1 (TRPV1) expression following transplantation.

Material/Methods

NSCs were cultured from the embryos of Sprague-Dawley rats (E12.5). Four group of rats (n=10, each) were subjected to SCI and allowed to recover for 1 week. Recombinant VEGF-NSCs, normal NSCs and PBS were intrathecally administered to the rats. VEGF and TRPV-1 expression at mRNA and protein level was evaluated. ELISA was performed to determine the release of neurotrophic factors after the transplantation. Motor neurons and axons were counted and the motor behavioral outcome was assessed using the rota-rod test.

Results

VEGF-NSC transgene transplantation resulted in an enhanced neuronal repair and motor behavioral outcome compared to the normal NSCs transplanted group. VEGF-NSCs increased the release of neurotrophic factors and reduced the expression of TRPV1.

Conclusions

Recombinant VEGF-NSCs transplantation following SCI is more efficacious compared to normal NSC transplantation. This might also be related to a reduced pain in the process of recovery due to reduced TRPV1 expression.