Tissue sparing, behavioral recovery, supraspinal axonal sparing/regeneration following sub-acute glial transplantation in a model of spinal cord contusion

Abstract

BackgroundIt has been shown that olfactory ensheathing glia (OEG) and Schwann cell (SCs) transplantation are beneficial as cellular treatments for spinal cord injury (SCI), especially acute and sub-acute time points. In this study, we transplanted DsRED transduced adult OEG and SCs sub-acutely (14 days) following a T10 moderate spinal cord contusion injury in the rat. Behaviour was measured by open field (BBB) and horizontal ladder walking tests to ascertain improvements in locomotor function. Fluorogold staining was injected into the distal spinal cord to determine the extent of supraspinal and propriospinal axonal sparing/regeneration at 4 months post injection time point. The purpose of this study was to investigate if OEG and SCs cells injected sub acutely (14 days after injury) could: (i) improve behavioral outcomes, (ii) induce sparing/regeneration of propriospinal and supraspinal projections, and (iii) reduce tissue loss.ResultsOEG and SCs transplanted rats showed significant increased locomotion when compared to control injury only in the open field tests (BBB). However, the ladder walk test did not show statistically significant differences between treatment and control groups. Fluorogold retrograde tracing showed a statistically significant increase in the number of supraspinal nuclei projecting into the distal spinal cord in both OEG and SCs transplanted rats. These included the raphe, reticular and vestibular systems. Further pairwise multiple comparison tests also showed a statistically significant increase in raphe projecting neurons in OEG transplanted rats when compared to SCs transplanted animals. Immunohistochemistry of spinal cord sections short term (2 weeks) and long term (4 months) showed differences in host glial activity, migration and proteoglycan deposits between the two cell types. Histochemical staining revealed that the volume of tissue remaining at the lesion site had increased in all OEG and SCs treated groups. Significant tissue sparing was observed at both time points following glial SCs transplantation. In addition, OEG transplants showed significantly decreased chondroitin proteoglycan synthesis in the lesion site, suggesting a more CNS tolerant graft.ConclusionsThese results show that transplantation of OEG and SCs in a sub-acute phase can improve anatomical outcomes after a contusion injury to the spinal cord, by increasing the number of spared/regenerated supraspinal fibers, reducing cavitation and enhancing tissue integrity. This provides important information on the time window of glial transplantation for the repair of the spinal cord.

Does the preclinical evidence for functional remyelination following myelinating cell engraftment into the injured spinal cord support progression to clinical trials?

“…However, myelin was not assessed and the source of variability between these studies is unclear. Three additional studies, not from within the final 6, compared transplantation of OEGs and SCs (Barakat et al, 2005; Barbour et al, 2013; Li et al, 2012). Significant improvement in BBB scores was seen for both groups, but media was the only control used.…”

Transplantation of Olfactory Ensheathing Cells in Spinal Cord Injury

“…However, in mice there are no such suitable differential cell surface markers that have been identified to date that can be used to separate OECs and Schwann cells effectively. Comparisons have been made between the efficacy of Schwann cells versus OECs for repair of the injured spinal cord with the results typically showing that both OECs and Schwann cells can enhance the anatomical or functional outcomes although with differences between the cell types depending on the assay (Lankford et al 2008;Li et al 2012;Barbour et al 2013). While the proportion of contaminating Schwann cells is likely to be low in OEC cultures, it should still be considered that Schwann cells could be contributing to the results of spinal repair transplantation studies and may be a source of the variation in outcomes that are observed.…”

Designer, injectable gels to prevent transplanted Schwann cell loss during spinal cord injury therapy

“…SCs were expanded in growth medium [Dulbecco's modified Eagle's medium (DMEM), fetal bovine serum, GlutaMAX, Antibiotic-Antimycotic (ABAM) (Life Technologies), pituitary extract (20 g/ml; Gibco), and 2 M forskolin (Sigma)] on poly-llysine-coated tissue culture plastic following a previously described protocol ( fig. S8) (12). SCs were used between passages 2 and 4 for all in vitro and in vivo studies.…”

“…Female Fischer 344 rats were used as animal models to determine the efficacy of delivering SCs within SHIELD for functional recovery after SCI. Numbers of animals per group were between 4 and 5 for 48 hours and between 8 and 10 for 4 weeks after transplantation based on (i) power analysis study to determine experimental numbers in animal models of SCIs to appropriately assess statistical differences and (ii) previous publications from the laboratory (table S2) (12). Transplantation studies were completed in two separate, independent studies to demonstrate reproducibility.…”