Propofol injection combined with bone marrow mesenchymal stem cell transplantation better improves electrophysiological function in the hindlimb of rats with spinal cord injury than monotherapy

Stem Cell Therapy for Spinal Cord Injury

Traumatic spinal cord injury (SCI) results in direct and indirect damage to neural tissues, which results in motor and sensory dysfunction, dystonia, and pathological reflex that ultimately lead to paraplegia or tetraplegia. A loss of cells, axon regeneration failure, and time-sensitive pathophysiology make tissue repair difficult. Despite various medical developments, there are currently no effective regenerative treatments. Stem cell therapy is a promising treatment for SCI due to its multiple targets and reactivity benefits. The present review focuses on SCI stem cell therapy, including bone marrow mesenchymal stem cells, umbilical mesenchymal stem cells, adipose-derived mesenchymal stem cells, neural stem cells, neural progenitor cells, embryonic stem cells, induced pluripotent stem cells, and extracellular vesicles. Each cell type targets certain features of SCI pathology and shows therapeutic effects via cell replacement, nutritional support, scaffolds, and immunomodulation mechanisms. However, many preclinical studies and a growing number of clinical trials found that single-cell treatments had only limited benefits for SCI. SCI damage is multifaceted, and there is a growing consensus that a combined treatment is needed.

Transplantation of rat-derived microglial cells promotes functional recovery in a rat model of spinal cord injury

This study evaluated the effect of microglia transplantation on neurological functional recovery in rats subjected to traumatic spinal cord injury (SCI). The rat model of SCI was established using a weight drop device. Forty SCI rats were randomly divided into the microglia group and the saline group. Then, rat-derived microglial cells or normal saline was injected into the injured site 7 days after surgery. The Basso-Beattie-Bresnahan (BBB) score, inclined plate test, and motor-evoked potentials (MEPs) were applied to assess the recovery of motor function. Hematoxylin and eosin (H&E) staining was used to assess the therapeutic effect. Microglia transplantation significantly improved BBB scores and functional scores at 2, 3, 4, 6, and 8 weeks after surgery compared to saline injection (P<0.05). Meanwhile, a prolonged MEP latency and decreased MEP amplitude were observed at 4 and 8 weeks in the microglia group (P<0.05). Histological analysis showed less damage and better prognosis in SCI rats of the microglia group. BrdU⁺ cell tracing experiments showed that microglia were recruited to the injured area of the spinal cord at 7 and 14 days after transplantation. The intensity of immunofluorescence was increased in CD68⁺ and OX42⁺ microglia at 2 days, 1 week, and 2 weeks, and then decreased at 3 and 4 weeks after transplantation in the microglia group. The transplantation of activated microglia played a key role in promoting the recovery of spinal cord function in a rat model of SCI.

Rat vibrissa dermal papilla cells promote healing of spinal cord injury following transplantation

Bone marrow mesenchymal stem cell (BMSC) transplantation is effective for repairing spinal cord injuries (SCIs); however, there are limitations of clinical BMSC applications. Previously, we reported that dermal papilla cells (DPCs) secrete brain-derived neurotrophic factor and glial cell line-derived neurotrophic factor more actively than BMSCs. To analyze the therapeutic function of DPCs in SCI, primary DPCs and BMSCs were cultured from the same green fluorescence protein-transgenic rat. The cells were suspended in rat-tail collagen I and transplanted separately into completely transected spinal cord lesion sites. Grafted-cell survival was examined with a small animal in vivo imaging detection system, and lesion sites were examined histochemically. In vivo imaging revealed enhanced lesion filling and survival with DPC grafts compared with BMSC grafts on days 14 and 21 post-transplantation. Hematoxylin and eosin staining demonstrated that lesion area sizes in the two groups were not markedly different. In the DPC transplant group, more axons formed within the lesion sites. CD31-positive vessel-like structures were more abundant in lesion sites near the grafted cells in the DPC group. The results of the present study suggest that DPCs may be a valuable alternative source of stem cells for autologous cell therapy for the treatment of SCI.

Propofol protects against blood-spinal cord barrier disruption induced by ischemia/reperfusion injury

Propofol has been shown to exert neuroprotective effects on the injured spinal cord. However, the effect of propofol on the blood-spinal cord barrier (BSCB) after ischemia/reperfusion injury (IRI) is poorly understood. Therefore, we investigated whether propofol could maintain the integrity of the BSCB. Spinal cord IRI (SCIRI) was induced in rabbits by infrarenal aortic occlusion for 30 minutes. Propofol, 30 mg/kg, was intravenously infused 10 minutes before aortic clamping as well as at the onset of reperfusion. Then, 48 hours later, we performed histological and mRNA/protein analyses of the spinal cord. Propofol decreased histological damage to the spinal cord, attenuated the reduction in BSCB permeability, downregulated the mRNA and protein expression levels of matrix metalloprotease-9 (MMP-9) and nuclear factor-κB (NF-κB), and upregulated the protein expression levels of occludin and claudin-5. Our findings suggest that propofol helps maintain BSCB integrity after SCIRI by reducing MMP-9 expression, by inhibiting the NF-κB signaling pathway, and by maintaining expression of tight junction proteins.

Stem Cells and Labeling for Spinal Cord Injury

Spinal cord injury (SCI) is a devastating condition that usually results in sudden and long-lasting locomotor and sensory neuron degeneration below the lesion site. During the last two decades, the search for new therapies has been revolutionized with the improved knowledge of stem cell (SC) biology. SCs therapy offers several attractive strategies for spinal cord repair. The transplantation of SCs promotes remyelination, neurite outgrowth and axonal elongation, and activates resident or transplanted progenitor cells across the lesion cavity. However, optimized growth and differentiation protocols along with reliable safety assays should be established prior to the clinical application of SCs. Additionally, the ideal method of SCs labeling for efficient cell tracking after SCI remains a challenging issue that requires further investigation. This review summarizes the current findings on the SCs-based therapeutic strategies, and compares different SCs labeling approaches for SCI.

Targeting the blood-spinal cord barrier: A therapeutic approach to spinal cord protection against ischemia-reperfusion injury

One of the principal functions of physical barriers between the blood and central nervous system protects system (i.e., blood brain barrier and blood-spinal cord barrier) is the protection from toxic and pathogenic agents in the blood. Disruption of blood-spinal cord barrier (BSCB) plays a key role in spinal cord ischemia-reperfusion injury (SCIRI). Following SCIRI, the permeability of the BSCB increases. Maintaining the integrity of the BSCB alleviates the spinal cord injury after spinal cord ischemia. This review summarizes current knowledge of the structure and function of the BSCB and its changes following SCIRI, as well as the prevention and cure of SCIRI and the role of the BSCB.