Preparation of Human Olfactory Ensheathing Cells for the Therapy of Spinal Cord Injuries

Application of cell transplantation in the treatment of neuropathic pain

Nerve injury can not only lead to sensory and motor dysfunction, but also be complicated with neuropathic pain (NPP), which brings great psychosomatic injury to patients. At present, there is no effective treatment for NPP. Based on the functional characteristics of cell transplantation in nerve regeneration and injury repair, cell therapy has been used in the exploratory treatment of NPP and has become a promising treatment of NPP. In this article, we discuss the current mainstream cell types for the treatment of NPP, including Schwann cells, olfactory ensheathing cells, neural stem cells and mesenchymal stem cells in the treatment of NPP. These bioactive cells transplanted into the host have pharmacological properties of decreasing pain threshold and relieving NPP by exerting nutritional support, neuroprotection, immune regulation, promoting axonal regeneration, and remyelination. Cell transplantation can also change the microenvironment around the nerve injury, which is conducive to the survival of neurons. It can effectively relieve pain by repairing the injured nerve and rebuilding the nerve function. At present, some preclinical and clinical studies have shown that some encouraging results have been achieved in NPP treatment based on cell transplantation. Therefore, we discussed the feasible strategy of cell transplantation as a treatment of NPP and the problems and challenges that need to be solved in the current application of cell transplantation in NPP therapy.

Features of Remyelination after Transplantation of Olfactory Ensheathing Cells with Neurotrophic Factors into Spinal Cord Cysts

This paper shows for the first time that co-transplantation of human olfactory ensheathing cells with neurotrophin-3 into spinal cord cysts is more effective for activation of remyelination than transplantation of cells with brain-derived neurotrophic factor and a combination of these two factors. The studied neurotrophic factors do not affect proliferation and migration of ensheathing cells in vitro. It can be concluded that the maximum improvement of motor function in rats receiving ensheathing cells with neurotrophin-3 is largely determined by activation of remyelination.

Application and challenges of olfactory ensheathing cells in clinical trials of spinal cord injury

Spinal cord injury (SCI) can lead to severe motor, sensory and autonomic nervous dysfunction, cause serious psychosomatic injury to patients. There is no effective treatment for SCI at present. In recent years, exciting evidence has been obtained in the application of cell-based therapy in basic research. These studies have revealed the fact that cells transplanted into the host can exert the pharmacological properties of treating and repairing SCI. Olfactory ensheathing cells (OECs) are a kind of special glial cells. The application value of OECs in the study of SCI lies in their unique biological characteristics, that is, they can survive and renew for life, give full play to neuroprotection, immune regulation, promoting axonal regeneration and myelination formation. The function of producing secretory group and improving microenvironment. This provides an irreplaceable treatment strategy for the repair of SCI. At present, some researchers have explored the possibility of treatment of OECs in clinical trials of SCI. Although OECs transplantation shows excellent safety and effectiveness in animal models, there is still lack of sufficient evidence to prove the effectiveness of their clinical application in clinical trials. There has been an obvious stagnation in the transformation of OECs transplantation into routine clinical practice, and clinical trials of cell therapy in this field are still facing major challenges and many problems that need to be solved. Therefore, this paper summarized and analyzed the clinical trials of OECs transplantation in the treatment of SCI, and discussed the problems and challenges of OECs transplantation in clinical trials.

Modeling of Alzheimer's Disease to Study the Efficacy of Cell Therapy (Review)

We analyzed the main approaches to the modeling of Alzheimer's disease for studying the effectiveness of cell therapy. Recent advances in regenerative medicine in the field of neuroscience create prospects for the use of various cell preparations for the treatment of Alzheimer's disease. Experimental data on the use of neural stem/progenitor cells, mesenchymal stem cells, embryonic stem cells, and induced pluripotent stem cells in various models of Alzheimer's disease are presented. Of particular importance is the standardization of protocols. The use of a standardized protocol in modeling of Alzheimer's disease will allow a comparative analysis of the effectiveness and safety of treatment to identify the optimal cell preparation. The data obtained on experimental animals can form the basis for further preclinical and clinical studies of cell therapy for Alzheimer's disease.

Cell therapies for spinal cord injury: a review of the clinical trials and cell-type therapeutic potential

Spinal cord injury (SCI) is an as yet untreatable neuropathology that causes severe dysfunction and disability. Cell-based therapies hold neuroregenerative and neuroprotective potential, but, although being studied in SCI patients for more than two decades, long-term efficacy and safety remain unproven, and which cell types result in higher neurological and functional recovery remains under debate. In a comprehensive scoping review of 142 reports and registries of SCI cell-based clinical trials, we addressed the current therapeutical trends and critically analysed the strengths and limitations of the studies. Schwann cells, olfactory ensheathing cells (OECs), macrophages and various types of stem cells have been tested, as well as combinations of these and other cells. A comparative analysis between the reported outcomes of each cell type was performed, according to gold-standard efficacy outcome measures like the ASIA impairment scale, motor and sensory scores. Most of the trials were in the early phases of clinical development (phase I/II), involved patients with complete chronic injuries of traumatic aetiology and did not display a randomized comparative control arm. Bone marrow stem cells and OECs were the most commonly tested cells, while open surgery and injection were the main methods of delivering cells into the spinal cord or submeningeal spaces. Transplantation of support cells, such as OECs and Schwann cells, resulted in the highest ASIA Impairment Scale (AIS) grade conversion rates (improvements in ∼40% of transplanted patients), which surpassed the spontaneous improvement rate expected for complete chronic SCI patients within 1 year post-injury (5-20%). Some stem cells, such as peripheral blood-isolated and neural stem cells, offer potential for improving patient recovery. Complementary treatments, particularly post-transplantation rehabilitation regimes, may contribute highly to neurological and functional recovery. However, unbiased comparisons between the tested therapies are difficult to draw, given the great heterogeneity of the design and outcome measures used in the SCI cell-based clinical trials and how these are reported. It is therefore crucial to standardize these trials when aiming for higher value clinical evidence-based conclusions.

Study of the Therapeutic Efficiency of Transduced Olfactory Ensheathing Cells in Spinal Cord Cysts

Posttraumatic spinal cord cysts are difficult to treat with medication and surgery. Gene-cell therapy is a promising area of treatment for such patients. However, optimal gene-cell construct for this therapy has not been developed. We investigated the therapeutic efficiency of human olfactory ensheathing cells (OECs) transduced by adenoviral vector encoding the mature form of brain-derived neurotrophic factor (mBDNF) in spinal cord cysts. The adenoviral vectors Ad5/35-CAG-mBDNF and Ad5/35-CAG-Fluc were constructed. Spinal cysts were modeled in female Wistar rats. We selected animals at the early and intermediate stages of recovery with scores to 13 according to the Basso, Beattie and Bresnahan (BBB) scale. The efficiency of therapy was evaluated by BBB tests. No cytotoxicity was detected using the Resazurin/AlamarBlue assay for both vectors at multiplicity of infection (MOIs) of 1, 5, and 25. There was an increase in the proliferation of cells treated with Ad5/35-CAG-mBDNF at MOIs of 5 and 25. The hind limb mobility after the transplantation of Ad5/35-CAG-mBDNF- and Ad5/35-CAG-Fluc-transduced human OECs and nontransduced OECs had approximately the same tendency to improve. Cyst reduction was observed with the transplantation of all the samples. Although Ad5/35-CAG-mBDNF-transduced OECs had high BDNF expression levels in vitro, these cells lacked positive effect in vivo because they did not exhibit significant effect concerning functional test when comparing the groups that received the same numbers of OECs. The therapeutic efficiency of transduced OECs appears to be due to the cell component. The autological and tissue-specific human OECs are promising for the personalized cell therapy. It is extremely important to test new gene-cell constructs based on these cells for further clinical use.

The Effect of Transplantation of Olfactory Ensheathing Cells on the Size of Posttraumatic Spinal Cord Cysts

We studied the effect of transplantation of ensheathing cells obtained from the olfactory mucosa of rats and humans on the size of posttraumatic spinal cord cysts. MRI examination showed that transplantation of these cells into experimental posttraumatic cysts of the spinal cord led to a significant decrease in cyst volume and even their complete disappearance in two animals receiving transplantation of rat or human cells. These findings attested to regenerative processes developing as a result of ensheathing cell transplantation. Further studies in this field will be aimed at elucidation of the mechanisms underlying spinal cord regeneration in the area of posttraumatic cysts after transplantation of ensheathing cells.

Combined Preparation of Human Olfactory Ensheathing Cells in the Therapy of Post-Traumatic Cysts of the Spinal Cord

In experiments on rats, co-transplantation of olfactory ensheathing cells of the human olfactory mucosa and neural stem/progenitor cells from the same source into post-traumatic cysts of the spinal cord led to improvement of the motor activity of the hind limbs and reduced the size of the cysts in some animals by 4-12%. The transplantation of a combination of the olfactory mucosa cells is effective and can be used in preclinical trials for the treatment of spinal cord injuries.

Neural Stem/Progenitor Cells of Human Olfactory Mucosa for the Treatment of Chronic Spinal Cord Injuries

We studied the efficiency of transplantation of neural stem/progenitor cells from human olfactory mucosa in chronic spinal cord injury. Neural stem/progenitor cells were obtained by a protocol modified by us and transplanted to rats with spinal post-traumatic cysts. It was shown that transplantation of neural stem/progenitor cells from human olfactory lining improved motor activity of hind limbs in the recipient rat with spinal post-traumatic cysts (according to BBB scale).

Comparison of the Efficiency of Transplantation of Rat and Human Olfactory Ensheathing Cells in Posttraumatic Cysts of the Spinal Cord

Olfactory ensheathing cells showed significant effects on the regeneration of the spinal cord in experimental models and in clinical trials. However, the use of these cells in the therapy of posttraumatic cysts of the spinal cord has not been studied. Cultures of human and rat olfactory mucosa were obtained according to the protocols developed by us. Passage 3-4 cultures are most enriched with olfactory ensheathing cells and are preferable for transplantation. We performed transplantation of 750,000 olfactory ensheathing cells into the region of modeled cysts. The therapeutic effect of human cells was more pronounced. The positive dynamics of recovery of motor activity in the hind limbs of rats can reflect regenerative processes in the spinal cord after transplantation of olfactory ensheathing cells into the region of posttraumatic cysts.

Efficiency of Human Olfactory Ensheathing Cell Transplantation into Spinal Cysts to Improve Mobility of the Hind Limbs

The pathological processes developing after spinal cord injuries often lead to formation of cysts. Existing surgical and medical methods are insufficient for treatment of post-traumatic spinal cord cysts. One of the emerging tools is cell therapy. Olfactory ensheathing cells (OECs) are perspective cells for cell therapy. In this study, we demonstrated that human OEC transplantation is effective in experimental spinal cysts. For our experiments, we selected animals only at the intermediate stage of recovery with scores from 8 to 13 according to the Basso, Beattie, and Bresnahan (BBB) scale. Cells were transplanted in different quantities (0.75 and 1.5 million) into the fully formed cysts and in the areas of injury without cysts. Improvement of limb mobility after human OEC transplantation into post-traumatic cysts was shown. In the group of rats with cysts, time-dependent increase in the BBB score was observed in subgroups treated with 0.75 and 1.5 million OECs with no statistically significant time-dependent dynamics of BBB values in the control group. When all three subgroups (control and two OEC doses) were compared, the Kruskal-Wallis test showed the presence of differences between subgroups after 1, 3, and 4 weeks of treatment with evidence of divergence increase. There was no statistically significant difference between the two doses of OEC treatment. The human OECs in the experiments without cysts were not effective. It was also shown that PKH26-labeled human OECs survive throughout the experiment and migrate to nearby areas of the cyst. Therefore, it was found that it is effective to transplant human OECs into fully formed cysts. In the future, autologous OECs can be used to personalize the treatment of patients with spinal cysts.

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.