人脐带间充质干细胞移植治疗脊髓损伤的研究进展

脊髓损伤（SCI）由于复杂病理生理和神经修复再生困难,至今仍旧是难以攻克的医学难题,而干细胞因其神经再生和神经保护特性被认为是治疗SCI最有希望的方法。其中人脐带间充质干细胞（HUC-MSCs）近年培养分化方法不断改进、神经修复机制初步阐明,联合移植等综合治疗方案也不断实践,使HUC-MSCs移植治疗效果提高。另外关于HUC-MSCs治疗SCI的临床试验逐渐开展,术后患者神经功能恢复改善且无严重并发症出现,表明干细胞移植应用于人体是安全有效的。本文就HUC-MSCs治疗SCI的研究状况及进展进行综述。     

Adult stem cell transplants for spinal cord injury repair: current state in preclinical research

Spinal cord injury (SCI) is a traumatic disorder resulting in a functional deficit that usually leads to severe and permanent paralysis. After the initial insult to the spinal cord, additional structure and function are lost through an active and complex secondary process. Since there is not effective treatment for SCI, several strategies including cellular, pharmacological and rehabilitation therapies have been approached in animal models. Some of them have been proved in clinical trials. In this review we focus on the current state of cell therapies, particularly on cells from adult origin, assayed in preclinical research. Cell types used in SCI therapy include Schwann cells, olfactory ensheathing cells and adult stem cells, such as neural stem cells, umbilical cord blood derived cells, mesenchymal stem cells or induced pluripotent stem cells. There are not yet conclusive evidences on which types of glial or adult stem cells are most effective in SCI treatment. Their ability to incorporate into the damaged spinal cord, to differentiate into neural lineages, to exert neuroprotective effects, to promote regeneration of damaged axons, and to improve functional deficits are still discussed, before translation towards clinical use, as a single therapy or in combination with other strategies.     

Testing Stem Cell Therapy in a Rat Model of Inflammatory Bowel Disease: Role of Bone Marrow Stem Cells and Stem Cell Factor in Mucosal Regeneration

Background

The gastrointestinal (GI) mucosal cells turnover regularly under physiological conditions, which may be stimulated in various pathological situations including inflammation. Local epithelial stem cells appear to play a major role in such mucosal renewal or pathological regeneration. Less is clear about the involvement of multipotent stem cells from blood in GI repair. We attempted to explore a role of bone marrow mesenchymal stromal cells (BMMSCs) and soluble stem cell factor (SCF) in GI mucosa regeneration in a rat model of inflammatory bowel diseases (IBD).

Methods

BMMSCs labelled with the fluorescent dye PKH26 from donor rats were transfused into rats suffering indomethacin-induced GI injury. Experimental effects by BMMSCs transplant and SCF were determined by morphometry of intestinal mucosa, double labeling of PKH26 positive BMMSCs with endogenous proliferative and intestinal cell markers, and western blot and PCR analyses of the above molecular markers in the recipient rats relative to controls.

Results

PKH26 positive BMMSCs were found in the recipient mucosa, partially colocalizing with the proliferating cell nuclear antigen (PCNA), Lgr5, Musashi-1 and ephrin-B3. mRNA and protein levels of PCNA, Lgr5, Musashi-1 and ephrin-B3 were elevated in the intestine in BMMSCs-treated rats, most prominent in the BMMSCs-SCF co-treatment group. The mucosal layer and the crypt layer of the small intestine were thicker in BMMSCs-treated rats, more evident in the BMMSCs-SCF co-treatment group.

Conclusion

BMMSCs and SCF participate in but may play a synergistic role in mucosal cell regeneration following experimentally induced intestinal injury. Bone marrow stem cell therapy and SCF administration may be of therapeutic value in IBD.     

Stem cell therapy: A novel approach for myocardial infarction

Myocardial infarction (MI) is a major cause of morbidity and mortality worldwide. Until recently, it was thought that myocardium was not able to repair itself, but studies have now shown that resident cardiac stem cells have regenerative capacity, and stem cell therapy may be a novel approach for cardiac muscle repair and regeneration. Stem cell-derived paracrine factors have been shown to regulate ventricular remodeling, inflammation, apoptosis, cardiomyocytes regeneration, and neovascularization in regions of infarcted cardiac tissue. In this review, we summarize the evidence from cellular, animal, and clinical studies supporting the potential clinical significance of stem cell therapy as a novel therapeutic approach for the treatment of MI.     

WJSC 6th Anniversary Special Issues（2）:Mesenchymal stem cells Mesenchymal stem cells in the treatment of spinal cord injuries:A review

With technological advances in basic research,the intricate mechanism of secondary delayed spinal cord injury(SCI)continues to unravel at a rapid pace.However,despite our deeper understanding of the molecular changes occurring after initial insult to the spinal cord,the cure for paralysis remains elusive.Current treatment of SCI is limited to early administration of high dose steroids to mitigate the harmful effect of cord edema that occurs after SCI and to reduce the cascade of secondary delayed SCI.R ecent evident-based clinical studies have cast doubt on the clinical benefit of steroids in SCI and intense focus on stem cell-based therapy has yielded some encouraging results.An array of mesenchymal stem cells(MSCs)from various sources with novel and promising strategies are being developed to improve function after SCI.In this review,we briefly discuss the pathophysiology of spinal cord injuries and characteristics and the potential sources of MSCs that can be used in the treatment of SCI.We will discuss the progress of MSCs application in research,focusing on the neuroprotective properties of MSCs.Finally,we will discuss the results from preclinical and clinical trials involving stem cell-based therapy in SCI.     

Endogenous neurogenesis following ischaemic brain injury: Insights for therapeutic strategies

Ischaemic stroke is among the most common yet most intractable types of central nervous system (CNS) injury in the adult human population. In the acute stages of disease, neurons in the ischaemic lesion rapidly die and other neuronal populations in the ischaemic penumbra are vulnerable to secondary injury. Multiple parallel approaches are being investigated to develop neuroprotective, reparative and regenerative strategies for the treatment of stroke. Accumulating evidence indicates that cerebral ischaemia initiates an endogenous regenerative response within the adult brain that potentiates adult neurogenesis from populations of neural stem and progenitor cells. A major research focus has been to understand the cellular and molecular mechanisms that underlie the potentiation of adult neurogenesis and to appreciate how interventions designed to modulate these processes could enhance neural regeneration in the post-ischaemic brain. In this review, we highlight recent advances over the last 5 years that help unravel the cellular and molecular mechanisms that potentiate endogenous neurogenesis following cerebral ischaemia and are dissecting the functional importance of this regenerative mechanism following brain injury.This article is part of a Directed Issue entitled: Regenerative Medicine: the challenge of translation.     

Injury-induced Cavl-expressing cells at lesion rostral side play major roles in spinal cord regeneration

The extent of cellular heterogeneity involved in neuronal regeneration after spinal cord injury (SCI) remains unclear. Therefore, we established stress-responsive transgenic zebrafish embryos with SCI. As a result, we found an SCI-induced cell population, termed SCI stress-responsive regenerating cells (SrRCs), essential for neuronal regeneration post-SCI. SrRCs were mostly composed of subtypes of radial glia (RGs-SrRCs) and neuron stem/progenitor cells (NSPCs-SrRCs) that are able to differentiate into neurons, and they formed a bridge across the lesion and connected with neighbouring undamaged motor neurons post-SCI. Compared to SrRCs at the caudal side of the SCI site (caudal-SrRCs), rostral-SrRCs participated more actively in neuronal regeneration. After RNA-seq analysis, we discovered that caveolin 1 (cav1) was significantly upregulated in rostral-SrRCs and that cav1 was responsible for the axonal regrowth and regenerative capability of rostral-SrRCs. Collectively, we define a specific SCI-induced cell population, SrRCs, involved in neuronal regeneration, demonstrate that rostral-SrRCs exhibit higher neuronal differentiation capability and prove that cav1 is predominantly expressed in rostral-SrRCs, playing a major role in neuronal regeneration after SCI.     

Integration and Long Distance Axonal Regeneration in the Central Nervous System from Transplanted Primitive Neural Stem Cells

Spinal cord injury (SCI) results in devastating motor and sensory deficits secondary to disrupted neuronal circuits and poor regenerative potential. Efforts to promote regeneration through cell extrinsic and intrinsic manipulations have met with limited success. Stem cells represent an as yet unrealized therapy in SCI. Recently, we identified novel culture methods to induce and maintain primitive neural stem cells (pNSCs) from human embryonic stem cells. We tested whether transplanted human pNSCs can integrate into the CNS of the developing chick neural tube and injured adult rat spinal cord. Following injection of pNSCs into the developing chick CNS, pNSCs integrated into the dorsal aspects of the neural tube, forming cell clusters that spontaneously differentiated into neurons. Furthermore, following transplantation of pNSCs into the lesioned rat spinal cord, grafted pNSCs survived, differentiated into neurons, and extended long distance axons through the scar tissue at the graft-host interface and into the host spinal cord to form terminal-like structures near host spinal neurons. Together, these findings suggest that pNSCs derived from human embryonic stem cells differentiate into neuronal cell types with the potential to extend axons that associate with circuits of the CNS and, more importantly, provide new insights into CNS integration and axonal regeneration, offering hope for repair in SCI.     

Augmenting peripheral nerve regeneration using stem cells: A review of current opinion

Outcomes following peripheral nerve injury remain frustratingly poor. The reasons for this are multifactorial, although maintaining a growth permissive environment in the distal nerve stump following repair is arguably the most important. The optimal environment for axonal regeneration relies on the synthesis and release of many biochemical mediators that are temporally and spatially regulated with a high level of incompletely understood complexity. The Schwann cell(SC) has emerged as a key player in this process. Prolonged periods of distal nerve stump denervation, characteristic of large gaps and proximal injuries, have been associated with a reduction in SC number and ability to support regenerating axons. Cell based therapy offers a potential therapy for the improvement of outcomes following peripheral nerve reconstruction. Stem cells have the potential to increase the number of SCs and prolong their ability to support regeneration. They may also have the ability to rescue and replenish populations of chromatolytic and apoptotic neurons following axotomy. Finally, they can be used in non-physiologic ways to preserve injured tissues such as denervated muscle while neuronal ingrowth has not yet occurred. Aside from stem cell type, careful consideration must be given to differentiation status, how stem cells are supported following transplantation and how they will be delivered to the site of injury. It is the aim of this article to review current opinions on the strategies of stem cell based therapy for the augmentation of peripheral nerve regeneration.     

Fibro-adipogenic progenitors in skeletal muscle homeostasis,regeneration and diseases

Skeletal muscle possesses a remarkable regenerative capacity that relies on the activity of muscle stem cells, also known as satellite cells. The presence of non-myogenic cells also plays a key role in the coordination of skeletal muscle regeneration. Particularly, fibro-adipogenic progenitors (FAPs) emerged as master regulators of muscle stem cell function and skeletal muscle regeneration. This population of muscle resident mesenchymal stromal cells has been initially characterized based on its bi-potent ability to differentiate into fibroblasts or adipocytes. New technologies such as single-cell RNAseq revealed the cellular heterogeneity of FAPs and their complex regulatory network during muscle regeneration. In acute injury, FAPs rapidly enter the cell cycle and secrete trophic factors that support the myogenic activity of muscle stem cells. Conversely, deregulation of FAP cell activity is associated with the accumulation of fibrofatty tissue in pathological conditions such as muscular dystrophies and ageing. Considering their central role in skeletal muscle pathophysiology, the regulatory mechanisms of FAPs and their cellular and molecular crosstalk with muscle stem cells are highly investigated in the field. In this review, we summarize the current knowledge on FAP cell characteristics, heterogeneity and the cellular crosstalk during skeletal muscle homeostasis and regeneration. We further describe their role in muscular disorders, as well as different therapeutic strategies targeting these cells to restore muscle regeneration.     

Functional recovery after spinal cord injury in dogs treated with a combination of Matrigel and neural-induced adipose-derived mesenchymal Stem cells

Background aimsPrevious studies have reported that scaffold or cell-based transplantation may improve functional recovery following spinal cord injury (SCI), but these results were based on neuronal regeneration and cell replacement. In this study, we investigated whether a combination of Matrigel and neural-induced mesenchymal stem cells (NMSC) improved hindlimb function in dogs with SCI, and what mechanisms were involved.MethodsWe pre-differentiated canine adipose-derived mesenchymal stem cells into NMSC. A total of 12 dogs subjected to SCI procedures were assigned to one of the following three transplantation treatment groups: phosphate-buffered saline (PBS); Matrigel; or Matrigel seeded with NMSC. Treatment occurred 1 week after SCI. Basso, Beattie and Bresnahan (B.B.B.) and Tarlov scores, histopathology, immunofluorescence staining and Western blot analysis were used to evaluate the treatment effects.ResultsCompared with dogs administered PBS or Matrigel alone, dogs treated with Matrigel + NMSC showed significantly better functional recovery 8 weeks after transplantation. Histology and immunochemical analysis revealed that the combination of Matrigel + NMSC reduced fibrosis from secondary injury processes and improved neuronal regeneration more than the other treatments. In addition, the combination of Matrigel + NMSC decreased the expression of inflammation and/or astrogliosis markers. Increased expressions of intracellular molecules related to neuronal extension, neuronal markers and neurotrophic factors were also found in the Matrigel + NMSC group. However, the expression of nestin as a neural stem cell marker was increased with Matrigel aloneConclusionsThe combination of Matrigel + NMSC produced beneficial effects in dogs with regard to functional recovery following SCI through enhancement of anti-inflammation, anti-astrogliosis, neuronal extension and neuronal regeneration effects.     

Spinal Cord Injury: Animal Models,Imaging Tools and the Treatment Strategies

Spinal cord injury (SCI) often leads to irreversible neuro-degenerative changes with life-long consequences. While there is still no effective therapy available, the results of past research have led to improved quality of life for patients suffering from partial or permanent paralysis. In this review we focus on the need, importance and the scientific value of experimental animal models simulating SCI in humans. Furthermore, we highlight modern imaging tools determining the location and extent of spinal cord damage and their contribution to early diagnosis and selection of appropriate treatment. Finally, we focus on available cellular and acellular therapies and novel combinatory approaches with exosomes and active biomaterials. Here we discuss the efficacy and limitations of adult mesenchymal stem cells which can be derived from bone marrow, adipose tissue or umbilical cord blood and its Wharton’s jelly. Special attention is paid to stem cell-derived exosomes and smart biomaterials due to their special properties as a delivery system for proteins, bioactive molecules or even genetic material.

     

Potential advantages of acute kidney injury management by mesenchymal stem cells

Mesenchymal stem cells are currently considered as a promising tool for therapeutic application in acute kidney injury (AKI) management. AKI is characterized by acute tubular injury with rapid loss of renal function. After AKI, inflammation, oxidative stress and excessive deposition of extracellular matrix are the molecular events that ultimately cause the end-stage renal disease. Despite numerous improvement of supportive therapy, the mortality and morbidity among patients remain high. Therefore, exploring novel therapeutic options to treat AKI is mandatory. Numerous evidence in animal models has demonstrated the capability of mesenchymal stem cells (MSCs) to restore kidney function after induced kidney injury. After infusion, MSCs engraft in the injured tissue and release soluble factors and microvesicles that promote cell survival and tissue repairing. Indeed, the main mechanism of action of MSCs in tissue regeneration is the paracrine/endocrine secretion of bioactive molecules. MSCs can be isolated from several tissues, including bone marrow, adipose tissue, and blood cord; pre-treatment procedures to improve MSCs homing and their paracrine function have been also described. This review will focus on the application of cell therapy in AKI and it will summarize preclinical studies in animal models and clinical trials currently ongoing about the use of mesenchymal stem cells after AKI.     

Mesenchymal Stem Cells in the Treatment of Human Spinal Cord Injury: The Effect on Individual Values of pNF-H,GFAP, S100 Proteins and Selected Growth Factors,Cytokines and Chemokines

At present, there is no effective way to treat the consequences of spinal cord injury (SCI). SCI leads to the death of neural and glial cells and widespread neuroinflammation with persisting for several weeks after the injury. Mesenchymal stem cells (MSCs) therapy is one of the most promising approaches in the treatment of this injury. The aim of this study was to characterize the expression profile of multiple cytokines, chemokines, growth factors, and so-called neuromarkers in the serum of an SCI patient treated with autologous bone marrow-derived MSCs (BM-MSCs). SCI resulted in a significant increase in the levels of neuromarkers and proteins involved in the inflammatory process. BM-MSCs administration resulted in significant changes in the levels of neuromarkers (S100, GFAP, and pNF-H) as well as changes in the expression of proteins and growth factors involved in the inflammatory response following SCI in the serum of a patient with traumatic SCI. Our preliminary results encouraged that BM-MSCs with their neuroprotective and immunomodulatory effects could affect the repair process after injury.     

EvoRegen in animals: Time to uncover deep conservation or convergence of adult stem cell evolution and regenerative processes

How do animals regenerate specialised tissues or their entire body after a traumatic injury, how has this ability evolved and what are the genetic and cellular components underpinning this remarkable feat? While some progress has been made in understanding mechanisms, relatively little is known about the evolution of regenerative ability. Which elements of regeneration are due to lineage specific evolutionary novelties or have deeply conserved roots within the Metazoa remains an open question. The renaissance in regeneration research, fuelled by the development of modern functional and comparative genomics, now enable us to gain a detailed understanding of both the mechanisms and evolutionary forces underpinning regeneration in diverse animal phyla. Here we review existing and emerging model systems, with the focus on invertebrates, for studying regeneration. We summarize findings across these taxa that tell us something about the evolution of adult stem cell types that fuel regeneration and the growing evidence that many highly regenerative animals harbor adult stem cells with a gene expression profile that overlaps with germline stem cells. We propose a framework in which regenerative ability broadly evolves through changes in the extent to which stem cells generated through embryogenesis are maintained into the adult life history.     

The effects of conditioned media generated by polarized macrophages on the cellular behaviours of bone marrow mesenchymal stem cells

Macrophages (Mφs) are involved in a variety of physiological and pathological events including wound healing and tissue regeneration, in which they play both positive and negative roles depending on their polarization state. In this study, we investigated the cellular behaviours of bone marrow mesenchymal stem cells (BMMSCs) after incubation in different conditioned media (CMs) generated by unpolarized Mφs (M0) or polarized Mφs (M1 and M2). Mφ polarization was induced by stimulation with various cytokines, and CMs were obtained from in vitro Mφ cultures termed CM0, CM1 and CM2 based on each Mφ phenotype. We found that CM1 supported the proliferation and adipogenic differentiation of BMMSCs, whereas CM0 had a remarkable effect on cell osteogenic differentiation. To a certain degree, CM2 also facilitated BMMSC osteogenesis; in particular, cells incubated with CM2 exhibited an enhanced capacity to form robust stem cell sheets. Although incubation with CM1 also increased production of extracellular matrix components, such as fibronectin, COL‐1 and integrin β1during sheet induction, the sheets generated by CM2‐incubated cells were thicker than those generated by CM1‐incubated cells (P < 0.001). Our data suggest that each Mφ phenotype has a unique effect on BMMSCs. Fine‐tuning Mφ polarization following transplantation may serve as an effective method to modulate the therapeutic potential of BMMSCs.     

脂肪干细胞在周围神经损伤修复中的作用

周围神经损伤的修复是临床外科中的一个难题。尽管周围神经系统在损伤后具有内在的自我修复能力,但一般很难达到完全功能恢复,特别是近端的损伤或者大段的神经缺损。近年来,基于干细胞的细胞治疗为周围神经再生带来了曙光。大量研究表明干细胞可促进周围神经损伤的再生,然而其作用机制还不明确。为此,本文将对脂肪干细胞在周围神经损伤修复中作用包括向雪旺细胞分化、神经营养、血管形成、神经元保护、靶器官保护和免疫调节等作用进行归纳,并进一步探讨其潜在的作用机制。