Long-Term Effects of Neural Precursor Cell Transplantation on Secondary Injury Processes and Functional Recovery after Severe Cervical Contusion-Compression Spinal Cord Injury.

Alexander Younsi,Moritz Scherer,Lennart Riemann,Guoli Zheng,Thomas Skutella,Mohamed Tail,Maryam Hatami,Klaus Zweckberger,Andreas Unterberg,Hao Zhang

doi:10.3390/ijms222313106

Abstract

Cervical spinal cord injury (SCI) remains a devastating event without adequate treatment options despite decades of research. In this context, the usefulness of common preclinical SCI models has been criticized. We, therefore, aimed to use a clinically relevant animal model of severe cervical SCI to assess the long-term effects of neural precursor cell (NPC) transplantation on secondary injury processes and functional recovery. To this end, we performed a clip contusion-compression injury at the C6 level in 40 female Wistar rats and a sham surgery in 10 female Wistar rats. NPCs, isolated from the subventricular zone of green fluorescent protein (GFP) expressing transgenic rat embryos, were transplanted ten days after the injury. Functional recovery was assessed weekly, and FluoroGold (FG) retrograde fiber-labeling, as well as manganese-enhanced magnetic resonance imaging (MEMRI), were performed prior to the sacrifice of the animals eight weeks after SCI. After cryosectioning of the spinal cords, immunofluorescence staining was conducted. Results were compared between the treatment groups (NPC, Vehicle, Sham) and statistically analyzed (p < 0.05 was considered significant). Despite the severity of the injury, leading to substantial morbidity and mortality during the experiment, long-term survival of the engrafted NPCs with a predominant differentiation into oligodendrocytes could be observed after eight weeks. While myelination of the injured spinal cord was not significantly improved, NPC treated animals showed a significant increase of intact perilesional motor neurons and preserved spinal tracts compared to untreated Vehicle animals. These findings were associated with enhanced preservation of intact spinal cord tissue. However, reactive astrogliosis and inflammation where not significantly reduced by the NPC-treatment. While differences in the Basso–Beattie–Bresnahan (BBB) score and the Gridwalk test remained insignificant, animals in the NPC group performed significantly better in the more objective CatWalk XT gait analysis, suggesting some beneficial effects of the engrafted NPCs on the functional recovery after severe cervical SCI.

Highlights

Spinal cord injury (SCI) remains a devastating event leading to loss of independence and often lifelong disability while incurring high socioeconomic costs [1,2]
In our study of cervical clip contusion-compression SCI with intraspinal transplantation of the neural precursor cell (NPC) in the subacute phase, engrafted cells were verifiable in the spinal cord even in the chronic phase eight weeks after the injury
Most of the surviving NPCs had differentiated towards the oligodendroglial lineage with 2636 ± 732 cells expressing green fluorescent protein (GFP) and the adenomatous polyposis coli (APC) protein, a marker for mature oligodendrocytes (46% of the surviving NPCs with a GFP+ /APC+ mature oligodendroglial immunophenotype; Figure 1B,C)

Summary

Introduction

Spinal cord injury (SCI) remains a devastating event leading to loss of independence and often lifelong disability while incurring high socioeconomic costs [1,2]. The transplantation of exogenous stem cells into the injured spinal cord to mimic such repair processes has become increasingly popular in recent years [10,11] and has shown promising results by, e.g., inhibiting inflammatory signaling, releasing trophic factors, or supplying an extracellular matrix [12,13] In this context, neural precursors cells (NPCs) have been especially attractive because they differentiate into both neurons and glial cells promoting remyelination and improving functional recovery after transplantation while not forming tumors in existing preclinical studies [8,14,15,16,17]. We, used a contusion-compression model of cervical SCI to assess the long-term effects of NPC-transplantation on relevant tissue and neurobehavioral outcomes, including myelination, spinal tract, and spinal cord tissue preservation, astroglial scarring, inflammation as well as gait and front- and hindlimb function

Methods

Results

Conclusion