Combination of olfactory ensheathing cells and human umbilical cord mesenchymal stem cell-derived exosomes promotes sciatic nerve regeneration

The role of exosomes derived from stem cells in nerve regeneration: A contribution to neurological repair

Stem cell-derived exosomes have gained attention in regenerative medicine for their role in encouraging nerve regeneration and potential use in treating neurological diseases. These nanosized extracellular vesicles act as carriers of bioactive molecules, facilitating intercellular communication and enhancing the regenerative process in neural tissues. This comprehensive study explores the methods by which exosomes produced from various stem cells contribute to nerve healing, with a particular emphasis on their role in angiogenesis, inflammation, and cellular signaling pathways. By examining cutting-edge developments and exploring the potential of exosomes in delivering disease-specific miRNAs and proteins, we highlight their versatility in tailoring personalized therapeutic strategies. The findings presented here highlight the potential of stem cell-produced exosomes for use in neurological diseases therapy, establishing the door for future research into exosome-based neurotherapies.

Exploring the Role of Mesenchymal Stem Cell-Derived Exosomes in Diabetic and Chemotherapy-Induced Peripheral Neuropathy

Diabetic and chemotherapy-induced peripheral neuropathies are known for long-term complications that are associated with uncontrolled hyperglycemia and cancer treatment, respectively. Peripheral neuropathy often requires long-term therapy and could persist after treatment provoking detrimental effects on the patient's quality of life. Despite continuous drug discoveries, development of efficient therapies is still needed for the significant management of diabetic and chemotherapy-induced peripheral neuropathy. Exosomes are nanosized extracellular vesicles that show great promise recently in tissue regeneration and injury repair compared to their parent stem cells. Herein, we provided a summary for the use of mesenchymal stem cell-derived exosomes in diabetic and chemotherapy-induced peripheral neuropathy in addition to recent advancements and ways proposed for the enhancement of their efficacy in these diseases.

Exosomes repairment for sciatic nerve injury: a cell-free therapy

Sciatic nerve injury (SNI) is a common type of peripheral nerve injury typically resulting from trauma, such as contusion, sharp force injuries, drug injections, pelvic fractures, or hip dislocations. It leads to both sensory and motor dysfunctions, characterized by pain, numbness, loss of sensation, muscle atrophy, reduced muscle tone, and limb paralysis. These symptoms can significantly diminish a patient's quality of life. Following SNI, Wallerian degeneration occurs, which activates various signaling pathways, inflammatory factors, and epigenetic regulators. Despite the availability of several surgical and nonsurgical treatments, their effectiveness remains suboptimal. Exosomes are extracellular vesicles with diameters ranging from 30 to 150 nm, originating from the endoplasmic reticulum. They play a crucial role in facilitating intercellular communication and have emerged as highly promising vehicles for drug delivery. Increasing evidence supports the significant potential of exosomes in repairing SNI. This review delves into the pathological progression of SNI, techniques for generating exosomes, the molecular mechanisms behind SNI recovery with exosomes, the effectiveness of combining exosomes with other approaches for SNI repair, and the changes and future outlook for utilizing exosomes in SNI recovery.

Recent perspectives on the synergy of mesenchymal stem cells with micro/nano strategies in peripheral nerve regeneration-a review

Despite the intrinsic repair of peripheral nerve injury (PNI), it is important to carefully monitor the process of peripheral nerve repair, as peripheral nerve regeneration is slow and incomplete in large traumatic lesions. Hence, mesenchymal stem cells (MSCs) with protective and regenerative functions are utilized in synergy with innovative micro/nano technologies to enhance the regeneration process of peripheral nerves. Nonetheless, as MSCs are assessed using standard regenerative criteria including sensory-motor indices, structural features, and morphology, it is challenging to differentiate between the protective and regenerative impacts of MSCs on neural tissue. This study aims to analyze the process of nerve regeneration, particularly the performance of MSCs with and without synergistic approaches. It also focuses on the paracrine secretions of MSCs and their conversion into neurons with functional properties that influence nerve regeneration after PNI. Furthermore, the study explores new ideas for nerve regeneration after PNI by considering the synergistic effect of MSCs and therapeutic compounds, neuronal cell derivatives, biological or polymeric conduits, organic/inorganic nanoparticles, and electrical stimulation. Finally, the study highlights the main obstacles to developing synergy in nerve regeneration after PNI and aims to open new windows based on recent advances in neural tissue regeneration.

Olfactory ensheathing cells as candidate cells for chronic pain treatment

Chronic pain is often accompanied by tissue damage and pain hypersensitivity. It easily relapses and is challenging to cure, which seriously affects the patients' quality of life and is an urgent problem to be solved. Current treatment methods primarily rely on morphine drugs, which do not address the underlying nerve injury and may cause adverse reactions. Therefore, in recent years, scientists have shifted their focus from chronic pain treatment to cell transplantation. This review describes the classification and mechanism of chronic pain through the introduction of the characteristics of olfactory ensheathing cells (OECs), an in-depth discussion of special glial cells through the phagocytosis of nerve debris, receptor-ligand interactions, providing nutrition, and other inhibition of neuroinflammation, and ultimately supporting axon regeneration and mitigation of chronic pain. This review summarizes the potential and limitations of OECs for treating chronic pain by objectively analyzing relevant clinical trials and methods to enhance efficacy and future development prospects.

The role of olfactory ensheathing cells in the repair of nerve injury

Cell transplantation has brought about a breakthrough in the treatment of nerve injuries, and the efficacy of cell transplantation compared to drug and surgical therapies is very exciting. In terms of transplantation targets, the classic cells include neural stem cells (NSCs) and Schwann cells, while a class of cells that can exist and renew throughout the life of the nervous system - olfactory ensheathing cells (OECs) - has recently been discovered in the olfactory system. OECs not only encircle the olfactory nerves but also act as macrophages and play an innate immune role. OECs can also undergo reprogramming to transform into neurons and survive and mature after transplantation. Currently, many studies have confirmed the repairing effect of OECs after transplantation into injured nerves, and safe and effective results have been obtained in clinical trials. However, the specific repair mechanism of OECs among them is not quite clear. For this purpose, we focus here on the repair mechanisms of OECs, which are summarized as follows: neuroprotection, secretion of bioactive factors, limitation of inflammation and immune regulation, promotion of myelin and axonal regeneration, and promotion of vascular proliferation. In addition, integrating the aspects of harvesting, purification, and prognosis, we found that OECs may be more suitable for transplantation than NSCs and Schwann cells, but this does not completely discard the value of these classical cells. Overall, OECs are considered to be one of the most promising transplantation targets for the treatment of nerve injury disorders.

Potential therapeutic effect of olfactory ensheathing cells in neurological diseases: neurodegenerative diseases and peripheral nerve injuries

Neurological diseases are destructive, mainly characterized by the failure of endogenous repair, the inability to recover tissue damage, resulting in the increasing loss of cognitive and physical function. Although some clinical drugs can alleviate the progression of these diseases, but they lack therapeutic effect in repairing tissue injury and rebuilding neurological function. More and more studies have shown that cell therapy has made good achievements in the application of nerve injury. Olfactory ensheathing cells (OECs) are a special type of glial cells, which have been proved to play an important role as an alternative therapy for neurological diseases, opening up a new way for the treatment of neurological problems. The functional mechanisms of OECs in the treatment of neurological diseases include neuroprotection, immune regulation, axon regeneration, improvement of nerve injury microenvironment and myelin regeneration, which also include secreted bioactive factors. Therefore, it is of great significance to better understand the mechanism of OECs promoting functional improvement, and to recognize the implementation of these treatments and the effective simulation of nerve injury disorders. In this review, we discuss the function of OECs and their application value in the treatment of neurological diseases, and position OECs as a potential candidate strategy for the treatment of nervous system diseases.

Stem cell-derived extracellular vesicle-based therapy for nerve injury: A review of the molecular mechanisms

Recent evidence suggests that stem cell therapy has beneficial effects on nerve damage. These beneficial effects were subsequently found to be exerted in part in a paracrine manner by the release of extracellular vesicles. Stem cell-secreted extracellular vesicles have shown great potential to reduce inflammation and apoptosis, optimize the function of Schwann cells, regulate genes related to regeneration, and improve behavioral performance after nerve damage. This review summarizes the current knowledge on the effect of stem cell-derived extracellular vesicles on neuroprotection and regeneration along with their molecular mechanisms after nerve damage.

miR-145a-5p/Plexin-A2 promotes the migration of OECs and transplantation of miR-145a-5p engineered OECs promotes the functional recovery in rats with SCI

BACKGROUND

Olfactory ensheathing cells (OECs) serve as a bridge by migrating at the site of spinal cord injury (SCI) to facilitate the repair of the neural structure and neural function. However, OEC migration at the injury site not only faces the complex and disordered internal environment but also is closely associated with the migration ability of OECs.

METHODS

We extracted OECs from the olfactory bulb of SD rats aged <7 days old. We verified the micro ribonucleic acid (miR)-145a-5p expression level in the gene chip after SCI and OEC transplantation using quantitative reverse transcription (qRT)-polymerase chain reaction (PCR). The possible target gene Plexin-A2 of miR-145a-5p was screened using bioinformatics and was verified using dual-luciferase reporter assay, Western blot, and qRT-PCR. The effect of miR-145a-5p/plexin-A2 on OEC migration ability was verified by wound healing assay, Transwell cell migration assay, and immunohistochemistry. Nerve regeneration was observed at the injured site of the spinal cord after OEC transplantation using tissue immunofluorescence and magnetic resonance imaging, diffusion tensor imaging, and the Basso-Beattie-Bresnahan locomotor rating scale were further used for imaging and functional evaluation.

RESULTS

miR-145a-5p expression in the injured spinal cord tissue after SCI considerably decreased, while Plexin-A2 expression significantly increased. OEC transplantation can reverse miR-145a-5p and Plexin-A2 expression after SCI. miR-145a-5p overexpression enhanced the intrinsic migration ability of OECs. As a target gene of miR-145a-5p, Plexin-A2 hinders OEC migration. OEC transplantation overexpressing miR-145a-5p after SCI can increase miR-145a-5p levels in the spinal cord, reduce Plexin-A2 expression in the OECs and the spinal cord tissue, and promote OEC migration and distribution at the injured site. OEC transplantation overexpressing miR-145a-5p can promote the regeneration and repair of neural morphology and neural function.

CONCLUSIONS

Our study demonstrated that miR-145a-5p could promote OEC migration to the injured spinal cord after cell transplantation by down-regulating the target gene Plexin-A2, thereby repairing the neural structure and function after SCI in rats.

Research Advances on Stem Cell-Derived Extracellular Vesicles Promoting the Reconstruction of Alveolar Bone through RANKL/RANK/OPG Pathway

Periodontal bone tissue defects and bone shortages are the most familiar and troublesome clinical problems in the oral cavity. Stem cell-derived extracellular vesicles (SC-EVs) have biological properties similar to their sources, and they could be a promising acellular therapy to assist with periodontal osteogenesis. In the course of alveolar bone remodeling, the RANKL/RANK/OPG signaling pathway is an important pathway involved in bone metabolism. This article summarizes the experimental studies of SC-EVs applied for the therapy of periodontal osteogenesis recently and explores the role of the RANKL/RANK/OPG pathway in their mechanism of action. Their unique patterns will open a new field of vision for people, and they will help to advance a possible future clinical treatment.

Exploring the Physicochemical, Electroactive, and Biodelivery Properties of Metal Nanoparticles on Peripheral Nerve Regeneration

Despite the advances in the regeneration/rehabilitation field of damaged tissues, the functional recovery of peripheral nerves (PNs), especially in a long gap injury, is considered a great medical challenge. Recent progress in nanomedicine has provided great hope for PN regeneration through the strategy of controlling cell behavior by metal nanoparticles individually or loaded on scaffolds/conduits. Despite the confirmed toxicity of metal nanoparticles due to long-term accumulation in nontarget tissues, they play a role in the damaged PN regeneration based on the topography modification of scaffolds/conduits, enhancing neurotrophic factor secretion, the ion flow improvement, and the regulation of electrical signals. Determining the fate of neural progenitor cells would be a major achievement in PN regeneration, which seems to be achievable by metal nanoparticles through altering cell vital approaches and controlling their functions. Therefore, in this literature, an attempt was made to provide an overview of the effective activities of metal nanoparticles on the PN regeneration, until the vital clues of the PN regeneration and how they are changed by metal nanoparticles are revealed to the researcher.

Exosomes from Hair Follicle Epidermal Neural Crest Stem Cells Promote Acellular Nerve Allografts to Bridge Rat Facial Nerve Defects

Previous studies showed that acellular nerve allografts (ANAs) have been successfully utilized in repairing peripheral nerve defects, and exosomes produced by stem cells are useful in supporting axon regrowth after peripheral nerve injury. In this study, exosomes from hair follicle epidermal neural crest stem cells (EPI-NCSCs-Exos) combined with ANAs were used to bridge facial nerve defects. EPI-NCSCs-Exos were isolated by ultracentrifuge, and were identified. After coculture, EPI-NCSCs-Exos were internalized into dorsal root ganglions (DRGs) and schwann cells (SCs) in vitro, respectively. EPI-NCSCs-Exos elongate the length of axons and dendrites of DRGs, and accelerated the proliferation and migration of SCs, and increased neurotrophic factor expression of SCs as well. The next step was to assign 24 Sprague Dawley male rats randomly and equally into three groups: the autograft group, the ANA group, and the ANA + EPI-NCSCs-Exos group. Each rat manufactured a 5-mm gap of facial nerve defect and immediately bridged by the corresponding transplants, respectively. After surgery, behavioral changes and electrophysiological testing of each rat were observed and assessed. At 90 days postoperatively, the retrogradely fluorescent tracer-labeled neurons were successfully observed on the injured side in the three groups. Morphological changes of facial nerve regeneration were evaluated by transmission electron microscopy and semithin toluidine blue staining. The results showed that nerve fiber density, nerve fiber diameter, and myelin sheath thickness in the ANA group were significantly worse than those in the other two groups (P < 0.05). No significant difference in nerve fiber density and myelin sheath thickness was observed between the autograft group and the ANA + EPI-NCSCs-Exos group (P = 0.14; P = 0.23). Our data indicated that EPI-NCSCs-Exos facilitate ANAs to bridge facial nerve defects and have the potential to replace autograft therapy in clinic.

The therapeutical effects of damage-specific stress induced exosomes on the cisplatin nephrotoxicity IN VIVO

Cisplatin is one of the metal containing drugs for the solid cancer treatments. However, its side-effects limit its application in the cancer treatment. Stem cell therapy is a promising treatment for the tissue damage caused by the chemotherapeutic agents, like cisplatin. Exosomes secreted by mesenchymal stem cells (MSCs) could be used for cell-free regenerative treatment, but their potency and reproducibility are questionable. In this study, the microenvironment of the renal tubular epithelial cells was mimicked by coculture of endothelial-, renal proximal tubule epithelial- and fibroblast cells. Cisplatin was applied to this tricell culture model, and the secreted rescue signals were collected and used to induce MSCs. From these stress-induced MSCs, the (stress-induced) exosomes were collected and used for the cell-free therapeutic treatment of cisplatin-treated rats with acute kidney injury. The composition of the stress-induces exosomes was compared with the non-induced exosomes and found that the expression of some critical factors for cell proliferation, repair mechanism and oxidative stress was improved. The cisplatin-damaged renal tissue showed substantial recovery after the treatment with stress-induced exosomes compared to the treatment with non-induced exosomes. Although, the non-induced exosomes showed their activity mostly as cytoprotective, the induced exosomes further involved actively in the tissue regeneration, like MSCs. It was shown that the exosomes could be reprogrammed to improve their therapeutic effect to be used in cell-free regenerative medicine. Further, cisplatin-induced tissue damage in the kidney might be effectively prevented and used for tissue regeneration by use of induced exosomes generated for a particular damage.

Role of exosomes in the pathogenesis, diagnosis, and treatment of central nervous system diseases

Central nervous system (CNS) diseases, such as multiple sclerosis, Alzheimer's disease (AD), and Parkinson’s disease (PD), affect millions of people around the world. Great efforts were put in disease related research, but few breakthroughs have been made in the diagnostic and therapeutic approaches. Exosomes are cell-derived extracellular vesicles containing diverse biologically active molecules secreted by their cell of origin. These contents, including nucleic acids, proteins, lipids, amino acids, and metabolites, can be transferred between different cells, tissues, or organs, regulating various intercellular cross-organ communications and normal and pathogenic processes. Considering that cellular environment and cell state strongly impact the content and uptake efficiency of exosomes, their detection in biological fluids and content composition analysis potentially offer a multicomponent diagnostic readout of several human diseases. Recently, studies have found that aberrant secretion and content of exosomes are closely related to the pathogenesis of CNS diseases. Besides, loading natural cargoes, exosomes can deliver drugs cross the blood brain barrier, making them emerging candidates of biomarkers and therapeutics for CNS diseases. In this review, we summarize and discuss the advanced research progress of exosomes in the pathological processes of several CNS diseases in regarding with neuroinflammation, CNS repair, and pathological protein aggregation. Moreover, we propose the therapeutic strategies of applying exosomes to the diagnosis, early detection, and treatment of CNS diseases.

The Therapeutic Potential of Exosomes in Soft Tissue Repair and Regeneration

Soft tissue defects are common following trauma and tumor extirpation. These injuries can result in poor functional recovery and lead to a diminished quality of life. The healing of skin and muscle is a complex process that, at present, leads to incomplete recovery and scarring. Regenerative medicine may offer the opportunity to improve the healing process and functional outcomes. Barriers to regenerative strategies have included cost, regulatory hurdles, and the need for cell-based therapies. In recent years, exosomes, or extracellular vesicles, have gained tremendous attention in the field of soft tissue repair and regeneration. These nanosized extracellular particles (30-140 nm) can break the cellular boundaries, as well as facilitate intracellular signal delivery in various regenerative physiologic and pathologic processes. Existing studies have established the potential of exosomes in regenerating tendons, skeletal muscles, and peripheral nerves through different mechanisms, including promoting myogenesis, increasing tenocyte differentiation and enhancing neurite outgrowth, and the proliferation of Schwann cells. These exosomes can be stored for immediate use in the operating room, and can be produced cost efficiently. In this article, we critically review the current advances of exosomes in soft tissue (tendons, skeletal muscles, and peripheral nerves) healing. Additionally, new directions for clinical applications in the future will be discussed.

Functional tissue-engineered microtissue formed by self-aggregation of cells for peripheral nerve regeneration

Background

Peripheral nerve injury (PNI) is one of the essential causes of physical disability with a high incidence rate. The traditional tissue engineering strategy, Top-Down strategy, has some limitations. A new tissue-engineered strategy, Bottom-Up strategy (tissue-engineered microtissue strategy), has emerged and made significant research progress in recent years. However, to the best of our knowledge, microtissues are rarely used in neural tissue engineering; thus, we intended to use microtissues to repair PNI.

Methods

We used a low-adhesion cell culture plate to construct adipose-derived mesenchymal stem cells (ASCs) into microtissues in vitro, explored the physicochemical properties and microtissues components, compared the expression of cytokines related to nerve regeneration between microtissues and the same amount of two-dimension (2D)-cultured cells, co-cultured directly microtissues with dorsal root ganglion (DRG) or Schwann cells (SCs) to observe the interaction between them using immunocytochemistry, quantitative reverse transcription polymerase chain reaction (qRT-PCR), enzyme-linked immunosorbent assay (ELISA). We used grafts constructed by microtissues and polycaprolactone (PCL) nerve conduit to repair sciatic nerve defects in rats.

Results

The present study results indicated that compared with the same number of 2D-cultured cells, microtissue could secrete more nerve regeneration related cytokines to promote SCs proliferation and axons growth. Moreover, in the direct co-culture system of microtissue and DRG or SCs, axons of DRG grown in the direction of microtissue, and there seems to be a cytoplasmic exchange between SCs and ASCs around microtissue. Furthermore, microtissues could repair sciatic nerve defects in rat models more effectively than traditional 2D-cultured ASCs.

Conclusion

Tissue-engineered microtissue is an effective strategy for stem cell culture and therapy in nerve tissue engineering.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02676-0.

Delving into the recent advancements of spinal cord injury treatment: a review of recent progress

Spinal cord injury (SCI) research is a very complex field lending to why reviews of SCI literatures can be beneficial to current and future researchers. This review focuses on recent articles regarding potential modalities for the treatment and management of SCI. The modalities were broken down into four categories: neuroprotection-pharmacologic, neuroprotection-non-pharmacologic, neuroregeneration-pharmacologic, neuroregeneration-non-pharmacologic. Peer-reviewed articles were found using PubMed with search terms: "spinal cord injury", "spinal cord injury neuroregeneration", "olfactory ensheathing cells spinal cord injury", "rho-rock inhibitors spinal cord injury", "neural stem cell", "scaffold", "neural stem cell transplantation", "exosomes and SCI", "epidural stimulation SCI", "brain-computer interfaces and SCI". Most recent articles spanning two years were chosen for their relevance to the categories of SCI management and treatment. There has been a plethora of pre-clinical studies completed with their results being difficult to replicate in clinical studies. Therefore, scientists should focus on understanding and applying the results of previous research to develop more efficacious preclinical studies and clinical trials.

Designing Olfactory Ensheathing Cell Transplantation Therapies: Influence of Cell Microenvironment

Olfactory ensheathing cell (OEC) transplantation is emerging as a promising treatment option for injuries of the nervous system. OECs can be obtained relatively easily from nasal biopsies, and exhibit several properties such as secretion of trophic factors, and phagocytosis of debris that facilitate neural regeneration and repair. But a major limitation of OEC-based cell therapies is the poor survival of transplanted cells which subsequently limit their therapeutic efficacy. There is an unmet need for approaches that enable the in vitro production of OECs in a state that will optimize their survival and integration after transplantation into the hostile injury site. Here, we present an overview of the strategies to modulate OECs focusing on oxygen levels, stimulating migratory, phagocytic, and secretory properties, and on bioengineering a suitable environment in vitro.

Extracellular vesicles and their role in peripheral nerve regeneration

Peripheral nerve injuries often result in sensory and motor dysfunction in respective parts of the body. Regeneration after peripheral nerve injuries is a complex process including the differentiation of Schwann cells, recruiting of macrophages, blood vessel growth and axonal regrowth. Extracellular vesicles (EVs) are considered to play a pivotal role in intercellular communication and transfer of biological information. Specifically, their bioactivity and ability to deliver cargos of various types of nucleic acids and proteins have made them a potential vehicle for neurotherapeutics. However, production, characterization, dosage and targeted delivery of EVs still pose challenges for the clinical translation of EV therapeutics. This review summarizes the current knowledge of EVs in the context of the healthy and injured peripheral nerve and addresses novel concepts for modification of EVs as therapeutic agents for peripheral nerve regeneration.

Human olfactory ensheathing cell-derived extracellular vesicles: miRNA profile and neuroprotective effect

BACKGROUND

Extracellular vesicle (EV)-based therapy has been identified as a leading alternative approach in several disease models. EV derived from the olfactory ensheathing cell (OEC) has been documented for its strong neuro-regenerative capacity. However, no information on its cargo that may contribute to its therapeutic effect has been available.

OBJECTIVE

To report the first miRNA profile of human OEC (hOEC) -EV, and investigate the neuroprotective effects.

METHODS

hOEC-EV was isolated and sequenced. We established in vitro experiments to assess the therapeutic potential of hOEC-EVs with respect to insulted neural progenitor cells (NPCs), and the angiogenesis effect. Secondary post-injury insults were imitated using t-BHP-mediated oxidative stress.

RESULTS

We noted a strong abundance of hOEC-EV-miRNAs, including hsa-miR148a-3p, has-miR151a-3p and several members of let-7 family. The common targets of 15 miRNAs among the top 20 miRNAs were thrombospondin 1 and cyclin dependent kinase 6. We demonstrated that hOEC-EVs promote normal NPC proliferation and differentiation to neuron-like morphologies with prolonged axons. hOEC-EVs protect cells from t-BHP mediated apoptosis. We also found that the migration rate of either NPCs or endothelial cells significantly improved with hOEC-EVs. Furthermore, in vitro tube formation assays indicated that angiogenesis, an important process for tissue repair, was significantly enhanced in human umbilical vein endothelial cells exposed to hOEC-EVs.

CONCLUSION

Our results revealed that hOEC-EVs exert neuroprotective effects by protecting cells from apoptosis and promoting in vitro biological processes that are important to neural tissue repair, including neural cell proliferation, axonal growth, and cell migration, in addition to enhancing angiogenesis. </p>.

Peripheral Nerve Regeneration Using Different Germ Layer-Derived Adult Stem Cells in the Past Decade

Peripheral nerve injuries (PNIs) are some of the most common types of traumatic lesions affecting the nervous system. Although the peripheral nervous system has a higher regenerative ability than the central nervous system, delayed treatment is associated with disturbances in both distal sensory and functional abilities. Over the past decades, adult stem cell-based therapies for peripheral nerve injuries have drawn attention from researchers. This is because various stem cells can promote regeneration after peripheral nerve injuries by differentiating into neural-line cells, secreting various neurotrophic factors, and regulating the activity of in situ Schwann cells (SCs). This article reviewed research from the past 10 years on the role of stem cells in the repair of PNIs. We concluded that adult stem cell-based therapies promote the regeneration of PNI in various ways.

Mesenchymal stem cell-derived exosomes: a promising vector in treatment for diabetes and its microvascular complications

Mesenchymal stem cell-derived exosomes (MSC-exos) are phospholipid bimolecular vesicles containing various materials, and they mediate crosstalk among cells. MSC-exos can maintain glucose homeostasis and delay the progression of diabetes and its microvascular complications through multiple mechanisms, such as by improving β-cell viability and insulin resistance as well as through multiple signal transduction pathways. However, related knowledge has not yet been systematically summarized. Therefore, we reviewed the applications and relevant mechanisms of MSC-exos in treatments for diabetes and its microvascular complications, particularly treatments for improving islet β-cells viability, insulin resistance, diabetic nephropathy, and retinopathy.

Advances in mesenchymal stem cell exosomes: a review

Stem cells can be used for regenerative medicine and as treatments for disease. The application of tissue engineering-related transplantation, stem cells, and local changes in the microenvironment is expected to solve major medical problems. Currently, most studies focus on tissue repair and regeneration, and mesenchymal stem cells (MSCs) are among the most common research topics. MSCs are applicable as seed cells, and they represent one of the current hot topics in regenerative medicine research. However, due to storage limitations and because cell senescence occurs during in vitro expansion, their clinical application is challenging. Exosomes, which are secreted by MSCs through paracrine signalling, not only have the same effects as MSCs, but they also have the advantages of targeted delivery, low immunogenicity, and high repairability. This article reviews the acquisition methods, characteristics, biological functions, and clinical applications of exosomes.

Extracellular vesicles derived from mesenchymal stem cells: A platform that can be engineered

Mesenchymal stem cells play an important role in tissue damage and repair. This role is mainly due to a paracrine mechanism, and extracellular vesicles (EVs) are an important part of the paracrine function. EVs play a vital role in many aspects of cell homeostasis, physiology, and pathology, and EVs can be used as clinical biomarkers, vaccines, or drug delivery vehicles. A large number of studies have shown that EVs derived from mesenchymal stem cells (MSC-EVs) play an important role in the treatment of various diseases. However, the problems of low production, low retention rate, and poor targeting of MSC-EVs are obstacles to current clinical applications. The engineering transformation of MSC-EVs can make up for those shortcomings, thereby improving treatment efficiency. This review summarizes the latest research progress of MSC-EV direct and indirect engineering transformation from the aspects of improving MSC-EV retention rate, yield, targeting, and MSC-EV visualization research, and proposes some feasible MSC-EV engineering methods of transformation.

Transplantation of olfactory ensheathing cells combined with chitosan down-regulates the expression of P2X7 receptor in the spinal cord and inhibits neuropathic pain

BACKGROUND

Neuropathic pain (NPP) is the common symptom of most clinical diseases, and its treatment has always been a difficult problem at present. Therefore, the purpose of this study is to explore a new method for the treatment of NPP by transplanting olfactory ensheathing cells combined with chitosan (OECs-CS).

METHODS

Animal model of chronic compression sciatic nerve injury (CCI) was made, olfactory ensheathing cells (OECs) were cultured, chitosan (CS) biomaterials were prepared, and biocompatibility of OECs and CS were detected by MTT method, OECs and OECs-CS were transplanted into the site of the injured sciatic nerve respectively, behavioral method was used to measured the mechanical withdrawal thresholds (MWT) and thermal withdrawal latency (TWL) of rats. On days 7 and 14 after surgery, the expression level of P2X7 receptor (P2X7R) in the L4-5 spinal cord was measured by using in situ hybridization, western-blotting and qRT-PCR. To explore the therapeutic effect of OECs-CS transplantation on pain suppression.

RESULTS

After chronic compression sciatic nerve injury, the MWT and TWL of rats were significantly reduced, and the expression levels of P2X7R protein and mRNA in the L4-5 spinal cord was significantly increased. After the transplantation of OECs and OECs-CS, the expression levels of P2X7R was significantly reduced, and the MWT and TWL of rats were significantly increased. Importantly, compared with the transplantation of OECs, OECs-CS transplantation could better reduce the expression levels of P2X7R, and relieve hyperalgesia in rats. Moreover, compared with the CCI + OECs-CS group on days 7 after surgery, the expression levels of P2X7R in the CCI + OECs-CS group was reduced on days 14 after surgery, and the pain in rats was relieved.

CONCLUSION

OECs and OECs-CS transplantation can inhibit P2X7R overexpression mediated NPP, while OECs-CS transplantation has better therapeutic effect than OECs transplantation alone. Our results provide a novel method and theoretical basis for the treatment of NPP.