Human Epidural AD–MSC Exosomes Improve Function Recovery after Spinal Cord Injury in Rats

Functional biomaterials for modulating the dysfunctional pathological microenvironment of spinal cord injury

Spinal cord injury (SCI) often results in irreversible loss of sensory and motor functions, and most SCIs are incurable with current medical practice. One of the hardest challenges in treating SCI is the development of a dysfunctional pathological microenvironment, which mainly comprises excessive inflammation, deposition of inhibitory molecules, neurotrophic factor deprivation, glial scar formation, and imbalance of vascular function. To overcome this challenge, implantation of functional biomaterials at the injury site has been regarded as a potential treatment for modulating the dysfunctional microenvironment to support axon regeneration, remyelination at injury site, and functional recovery after SCI. This review summarizes characteristics of dysfunctional pathological microenvironment and recent advances in biomaterials as well as the technologies used to modulate inflammatory microenvironment, regulate inhibitory microenvironment, and reshape revascularization microenvironment. Moreover, technological limitations, challenges, and future prospects of functional biomaterials to promote efficient repair of SCI are also discussed. This review will aid further understanding and development of functional biomaterials to regulate pathological SCI microenvironment.

Applications of Stem Cell-Derived Extracellular Vesicles in Nerve Regeneration

Extracellular vesicles (EVs), including exosomes, microvesicles, and other lipid vesicles derived from cells, play a pivotal role in intercellular communication by transferring information between cells. EVs secreted by progenitor and stem cells have been associated with the therapeutic effects observed in cell-based therapies, and they also contribute to tissue regeneration following injury, such as in orthopaedic surgery cases. This review explores the involvement of EVs in nerve regeneration, their potential as drug carriers, and their significance in stem cell research and cell-free therapies. It underscores the importance of bioengineers comprehending and manipulating EV activity to optimize the efficacy of tissue engineering and regenerative therapies.

The role of small extracellular vesicles and microRNA as their cargo in the spinal cord injury pathophysiology and therapy

Spinal cord injury (SCI) is a devastating condition with a complex pathology that affects a significant portion of the population and causes long-term consequences. After primary injury, an inflammatory cascade of secondary injury occurs, followed by neuronal cell death and glial scar formation. Together with the limited regenerative capacity of the central nervous system, these are the main reasons for the poor prognosis after SCI. Despite recent advances, there is still no effective treatment. Promising therapeutic approaches include stem cells transplantation, which has demonstrated neuroprotective and immunomodulatory effects in SCI. This positive effect is thought to be mediated by small extracellular vesicles (sEVs); membrane-bound nanovesicles involved in intercellular communication through transport of functional proteins and RNA molecules. In this review, we summarize the current knowledge about sEVs and microRNA as their cargo as one of the most promising therapeutic approaches for the treatment of SCI. We provide a comprehensive overview of their role in SCI pathophysiology, neuroprotective potential and therapeutic effect.

The Translation of Nanomedicines in the Contexts of Spinal Cord Injury and Repair

PURPOSE OF THIS REVIEW

Manipulating or re-engineering the damaged human spinal cord to achieve neuro-recovery is one of the foremost challenges of modern science. Addressing the restricted permission of neural cells and topographically organised neural tissue for self-renewal and spontaneous regeneration, respectively, is not straightforward, as exemplified by rare instances of translational success. This review assembles an understanding of advances in nanomedicine for spinal cord injury (SCI) and related clinical indications of relevance to attempts to design, engineer, and target nanotechnologies to multiple molecular networks.

RECENT FINDINGS

Recent research provides a new understanding of the health benefits and regulatory landscape of nanomedicines based on a background of advances in mRNA-based nanocarrier vaccines and quantum dot-based optical imaging. In relation to spinal cord pathology, the extant literature details promising advances in nanoneuropharmacology and regenerative medicine that inform the present understanding of the nanoparticle (NP) biocompatibility-neurotoxicity relationship. In this review, the conceptual bases of nanotechnology and nanomaterial chemistry covering organic and inorganic particles of sizes generally less than 100 nm in diameter will be addressed. Regarding the centrally active nanotechnologies selected for this review, attention is paid to NP physico-chemistry, functionalisation, delivery, biocompatibility, biodistribution, toxicology, and key molecular targets and biological effects intrinsic to and beyond the spinal cord parenchyma.

SUMMARY

The advance of nanotechnologies for the treatment of refractory spinal cord pathologies requires an in-depth understanding of neurobiological and topographical principles and a consideration of additional complexities involving the research's translational and regulatory landscapes.

Role of epidural fat in the local milieu: what we know and what we don't

PURPOSE

Traditionally, the epidural fat (EF) is known as a physical buffer for the dural sac against the force and a lubricant facilitating the relative motion of the latter on the osseous spine. Along with the development of the studies on EF, controversies still exist on vital questions, such as the underlying mechanism of the spinal epidural lipomatosis. Meanwhile, the scattered and fragmented researches hinder the global insight into the seemingly dispensable tissue.

METHODS

Herein, we reviewed literature on the EF and its derivatives to elucidate the dynamic change and complex function of EF in the local milieu, especially at the pathophysiological conditions. We start with an introduction to EF and the current pathogenic landscape, emphasizing the interlink between the EF and adjacent structures. We generally categorize the major pathological changes of the EF into hypertrophy, atrophy, and inflammation.

RESULTS AND CONCLUSIONS

It is acknowledged that not only the EF (or its cellular components) may be influenced by various endogenic/exogenic and focal/systematic stimuli, but the adjacent structures can also in turn be affected by the EF, which may be a hidden pathogenic clue for specific spinal disease. Meanwhile, the unrevealed sections, which are also the directions the future research, are proposed according to the objective result and rational inference. Further effort should be taken to reveal the underlying mechanism and develop novel therapeutic pathways for the relevant diseases.

Hydrogel-encapsulated extracellular vesicles for the regeneration of spinal cord injury

Spinal cord injury (SCI) is a critical neurological condition that may impair motor, sensory, and autonomous functions. At the cellular level, inflammation, impairment of axonal regeneration, and neuronal death are responsible for SCI-related complications. Regarding the high mortality and morbidity rates associated with SCI, there is a need for effective treatment. Despite advances in SCI repair, an optimal treatment for complete recovery after SCI has not been found so far. Therefore, an effective strategy is needed to promote neuronal regeneration and repair after SCI. In recent years, regenerative treatments have become a potential option for achieving improved functional recovery after SCI by promoting the growth of new neurons, protecting surviving neurons, and preventing additional damage to the spinal cord. Transplantation of cells and cells-derived extracellular vesicles (EVs) can be effective for SCI recovery. However, there are some limitations and challenges related to cell-based strategies. Ethical concerns and limited efficacy due to the low survival rate, immune rejection, and tumor formation are limitations of cell-based therapies. Using EVs is a helpful strategy to overcome these limitations. It should be considered that short half-life, poor accumulation, rapid clearance, and difficulty in targeting specific tissues are limitations of EVs-based therapies. Hydrogel-encapsulated exosomes have overcome these limitations by enhancing the efficacy of exosomes through maintaining their bioactivity, protecting EVs from rapid clearance, and facilitating the sustained release of EVs at the target site. These hydrogel-encapsulated EVs can promote neuroregeneration through improving functional recovery, reducing inflammation, and enhancing neuronal regeneration after SCI. This review aims to provide an overview of the current research status, challenges, and future clinical opportunities of hydrogel-encapsulated EVs in the treatment of SCI.

Exosomal Cargo: Pro-angiogeneic, anti-inflammatory, and regenerative effects in ischemic and non-ischemic heart diseases - A comprehensive review

Heart diseases are the primary cause of mortality and morbidity worldwide which inflict a heavy social and economic burden. Among heart diseases, most deaths are due to myocardial infarction (MI) or heart attack, which occurs when a decrement in blood flow to the heart causes injury to cardiac tissue. Despite several available diagnostic, therapeutic, and prognostic approaches, heart disease remains a significant concern. Exosomes are a kind of small extracellular vesicles released by different types of cells that play a part in intercellular communication by transferring bioactive molecules important in regenerative medicine. Many studies have reported the diagnostic, therapeutic, and prognostic role of exosomes in various heart diseases. Herein, we reviewed the roles of exosomes as new emerging agents in various types of heart diseases, including ischemic heart disease, cardiomyopathy, arrhythmia, and valvular disease, focusing on pathogenesis, therapeutic, diagnostic, and prognostic roles in different areas. We have also mentioned different routes of exosome delivery to target tissues, the effects of preconditioning and modification on exosome's capability, exosome production in compliance with good manufacturing practice (GMP), and their ongoing clinical applications in various medical contexts to shed light on possible clinical translation.

Extracellular Vesicles from Human Adipose Tissue-Derived Mesenchymal Stem Cells Suppress RANKL-Induced Osteoclast Differentiation via miR122-5p

Researchers are increasingly interested in cell therapy using mesenchymal stem cells (MSCs) as an alternative remedy for osteoporosis, with fewer side effects. Thus, we isolated and characterized extracellular vesicles (EVs) from human adipose tissue-derived MSCs (hMSCs) and investigated their inhibitory effects on RANKL-induced osteoclast differentiation. Purified EVs were collected from the supernatant of hMSCs by tangential flow filtration. Characterization of EVs included typical evaluation of the size and concentration of EVs by nanoparticle tracking analysis and morphology analysis using transmission electron microscopy. hMSC-EVs inhibited RANKL-induced differentiation of bone marrow-derived macrophages (BMDMs) into osteoclasts in a dose-dependent manner. F-actin ring formation and bone resorption were also reduced by EV treatment of osteoclasts. In addition, EVs decreased RANKL-induced phosphorylation of p38 and JNK and expression of osteoclastogenesis-related genes in BMDMs treated with RANKL. To elucidate which part of the hMSC-EVs plays a role in the inhibition of osteoclast differentiation, we analyzed miRNA profiles in hMSC-EVs. The results showed that has-miR122-5p was present at significantly high read counts. Overexpression of miR122-5p in BMDMs significantly inhibited RANKL-induced osteoclast differentiation and induced defects in F-actin ring formation and bone resorption. Our results also revealed that RANKL-induced phosphorylation of p38 and JNK and osteoclast-specific gene expression was decreased by miR122-5p transfection, which was consistent with the results of hMSC-EVs. These findings suggest that hMSC-EVs containing miR122-5p inhibit RANKL-induced osteoclast differentiation via the downregulation of molecular mechanisms and could be a preventive candidate for destructive bone diseases.

A swift expanding trend of extracellular vesicles in spinal cord injury research: a bibliometric analysis

Extracellular vesicles (EVs) in the field of spinal cord injury (SCI) have garnered significant attention for their potential applications in diagnosis and therapy. However, no bibliometric assessment has been conducted to evaluate the scientific progress in this area. A search of articles in Web of Science (WoS) from January 1, 1991, to May 1, 2023, yielded 359 papers that were analyzed using various online analysis tools. These articles have been cited 10,842 times with 30.2 times per paper. The number of publications experienced explosive growth starting in 2015. China and the United States led this research initiative. Keywords were divided into 3 clusters, including "Pathophysiology of SCI", "Bioactive components of EVs", and "Therapeutic effects of EVs in SCI". By integrating the average appearing year (AAY) of keywords in VoSviewer with the time zone map of the Citation Explosion in CiteSpace, the focal point of research has undergone a transformative shift. The emphasis has moved away from pathophysiological factors such as "axon", "vesicle", and "glial cell" to more mechanistic and applied domains such as "activation", "pathways", "hydrogels" and "therapy". In conclusions, institutions are expected to allocate more resources towards EVs-loaded hydrogel therapy and the utilization of innovative materials for injury mitigation.

Mesenchymal stem cell-derived extracellular vesicles: emerging concepts in the treatment of spinal cord injury

Spinal cord injury (SCI) is a prevalent central nervous system disease with a high disability rate, leading to the loss of motor and sensory nerve function. Due to the complex pathophysiology of SCI, more effective clinical treatment strategies are needed. Research has indicated the considerable potential of extracellular vesicles (EVs) derived from mesenchymal stem cells (MSC-EVs) as a cell-free therapy in SCI repair and regeneration due to their ability to regulate immune cell activity and stimulate damaged neuron regeneration. Moreover, applying MSCs and engineered EVs can fully exploit the potential of MSC-EVs in spinal cord repair. Here, we outline the pathological process of SCI and its current clinical treatment status, summarize the latest MSC-EVs research and its pretreatment and engineering strategies in SCI treatment, and explore MSC-EVs application prospects.

The Role of Mesenchymal Stromal Cells and Their Products in the Treatment of Injured Spinal Cords

Spinal cord injury (SCI) is a destructive condition that results in lasting neurological damage resulting in disruption of the connection between the central nervous system and the rest of the body. Currently, there are several approaches in the treatment of a damaged spinal cord; however, none of the methods allow the patient to return to the original full-featured state of life before the injury. Cell transplantation therapies show great potential in the treatment of damaged spinal cords. The most examined type of cells used in SCI research are mesenchymal stromal cells (MSCs). These cells are at the center of interest of scientists because of their unique properties. MSCs regenerate the injured tissue in two ways: (i) they are able to differentiate into some types of cells and so can replace the cells of injured tissue and (ii) they regenerate tissue through their powerful known paracrine effect. This review presents information about SCI and the treatments usually used, aiming at cell therapy using MSCs and their products, among which active biomolecules and extracellular vesicles predominate.

Exosomes combined with biomaterials in the treatment of spinal cord injury

Spinal cord injury (SCI) is a serious and disabling disease with a high mortality rate. It often leads to complete or partial sensory and motor dysfunction and is accompanied by a series of secondary outcomes, such as pressure sores, pulmonary infections, deep vein thrombosis in the lower extremities, urinary tract infections, and autonomic dysfunction. Currently, the main treatments for SCI include surgical decompression, drug therapy, and postoperative rehabilitation. Studies have shown that cell therapy plays a beneficial role in the treatment of SCI. Nonetheless, there is controversy regarding the therapeutic effect of cell transplantation in SCI models. Meanwhile exosomes, as a new therapeutic medium for regenerative medicine, possess the advantages of small size, low immunogenicity, and the ability to cross the blood-spinal cord barrier. Certain studies have shown that stem cell-derived exosomes have anti-inflammatory effects and can play an irreplaceable role in the treatment of SCI. In this case, it is difficult for a single treatment method to play an effective role in the repair of neural tissue after SCI. The combination of biomaterial scaffolds and exosomes can better transfer and fix exosomes to the injury site and improve their survival rate. This paper first reviews the current research status of stem cell-derived exosomes and biomaterial scaffolds in the treatment of SCI respectively, and then describes the application of exosomes combined with biomaterial scaffolds in the treatment of SCI, as well as the challenges and prospects.

Exosomal LncRNAs in Gastrointestinal Cancer: Biological Functions and Emerging Clinical Applications

Due to the lack of specific and effective biomarkers and therapeutic targets, the early diagnosis and treatment of gastrointestinal cancer remain unsatisfactory. As a type of nanosized vesicles derived from living cells, exosomes mediate cell-to-cell communication by transporting bioactive molecules, thus participating in the regulation of many pathophysiological processes. Recent evidence has revealed that several long non-coding RNAs (lncRNAs) are enriched in exosomes. Exosomes-mediated lncRNAs delivery is critically involved in various aspects of gastrointestinal cancer progression, such as tumor proliferation, metastasis, angiogenesis, stemness, immune microenvironment, and drug resistance. Exosomal lncRNAs represent promising candidates to act as the diagnosis biomarkers and anti-tumor targets. This review introduces the major characteristics of exosomes and lncRNAs and describes the biological functions of exosomal lncRNAs in gastrointestinal cancer development. The preclinical studies on using exosomal lncRNAs to monitor and treat gastrointestinal cancer are also discussed, and the opportunities and challenges for translating them into clinical practice are evaluated.

Regenerative Effects of Exosomes-Derived MSCs: An Overview on Spinal Cord Injury Experimental Studies

Spinal cord injury (SCI) is a devastating condition usually induced by the initial mechanical insult that can lead to permanent motor and sensory deficits. At present, researchers are investigating potential therapeutic strategies to ameliorate the neuro-inflammatory cascade that occurs post-injury. Although the use of mesenchymal stromal/stem (MSCs) as a potential therapy in application to regenerative medicine promoted anti-inflammatory and neuroprotective effects, several disadvantages limit their use. Therefore, recent studies have reported the effects of exosomes-derived MSCs (MSC-EXOs) as an innovative therapeutic option for SCI patients. It is noteworthy that MSC-EXOs can maintain the integrity of the blood-spinal cord barrier (BSCB), promoting angiogenic, proliferative, and anti-oxidant effects, as well as immunomodulatory, anti-inflammatory, and antiapoptotic properties. Therefore, in this study, we summarized the preclinical studies reported in the literature that have shown the effects of MSC-EXOs as a new molecular target to counteract the devastating effects of SCI.

Therapeutic potential of small extracellular vesicles derived from mesenchymal stem cells for spinal cord and nerve injury

Neural diseases such as compressive, congenital, and traumatic injuries have diverse consequences, from benign mild sequelae to severe life-threatening conditions with associated losses of motor, sensory, and autonomic functions. Several approaches have been adopted to control neuroinflammatory cascades. Traditionally, mesenchymal stem cells (MSCs) have been regarded as therapeutic agents, as they possess growth factors and cytokines with potential anti-inflammatory and regenerative effects. However, several animal model studies have reported conflicting outcomes, and therefore, the role of MSCs as a regenerative source for the treatment of neural pathologies remains debatable. In addition, issues such as heterogeneity and ethical issues limited their use as therapeutic agents. To overcome the obstacles associated with the use of traditional agents, we explored the therapeutic potentials of extracellular vesicles (EVs), which contain nucleic acids, functional proteins, and bioactive lipids, and play crucial roles in immune response regulation, inflammation reduction, and cell-to-cell communication. EVs may surpass MSCs in size issue, immunogenicity, and response to the host environment. However, a comprehensive review is required on the therapeutic potential of EVs for the treatment of neural pathologies. In this review, we discuss the action mechanism of EVs, their potential for treating neural pathologies, and future perspectives regarding their clinical applications.

Multiple strategies enhance the efficacy of MSCs transplantation for spinal cord injury

Spinal cord injury (SCI) is a serious complication of the central nervous system (CNS) after spine injury, often resulting in severe sensory, motor, and autonomic dysfunction below the level of injury. To date, there is no effective treatment strategy for SCI. Recently, stem cell therapy has brought hope to patients with neurological diseases. Mesenchymal stem cells (MSCs) are considered to be the most promising source of cellular therapy after SCI due to their immunomodulatory, neuroprotective and angiogenic potential. Considering the limited therapeutic effect of MSCs due to the complex pathophysiological environment following SCI, this paper not only reviews the specific mechanism of MSCs to facilitate SCI repair, but also further discusses the research status of these pluripotent stem cells combined with other therapeutic approaches to promote anatomical and functional recovery post-SCI.