外胚间充质干细胞构建组织工程骨骼肌的应用研究

目的:探讨利用大鼠颌突外胚间充质干细胞构建组织工程骨骼肌的可行性,并观察对骨骼肌缺损的修复重建的促进效应。方法:取妊娠E 11.5胎鼠颌突外胚间充质干细胞,纯化后在含5ml/L体积浓度二甲基亚砜的DMEM/F12培养基中诱导分化为骨骼肌样细胞,将细胞种植于BAM膜上培养形成组织工程骨骼肌。将其移植入大鼠骨骼肌缺损模型,手术后14 d观察骨骼肌恢复情况,同期进行组织学及免疫组化染色鉴定。结果:经诱导后外胚间充质干细胞可向骨骼肌样细胞转化,构建的组织工程骨骼肌可加速缺损的修复重建,组织学染色显示外胚间充质干细胞具有正常骨骼肌的组织形态,可表达成肌相关蛋白MyOD。结论:诱导后的外胚间充质干细胞可作为种子细胞构建组织工程骨骼肌,本实验为临床肌肉的缺损修复奠定了理论基础。     

肝细胞生长因子在骨骼肌再生中的作用研究进展

骨骼肌损伤后的修复包括炎症反应期、修复期、组织重塑期三个阶段。而骨骼肌卫星细胞的激活、增殖与分化和骨骼肌伤后的修复有着密切的关系。骨骼肌损伤后,肝细胞生长因子(HGF)可以自分泌、旁分泌或内分泌的形式,调控肌卫星细胞功能,从而影响损伤骨骼肌的再生。其机制研究表明,HGF可能通过与其受体c-met结合,启动相关信号途径,参与骨骼肌卫星细胞激活、增殖、分化和迁移,从而影响骨骼肌再生进程。     

骨髓间充质干细胞成肌和成脂分化的调控

骨髓间充质干细胞(mesenchymal stem cells,MSCs)是来源于骨髓基质的一类具有高度自我更新能力和多向分化潜能的成体干细胞.因其具有容易获取、体外扩增方便迅速、移植排斥反应较弱等优点而成为临床应用的理想细胞模型.骨髓间充质干细胞向成肌和成脂的分化对动物机体内肌肉和脂肪的组成具有直接影响,因而与肉品质及人类健康息息相关.本文综述了骨髓间充质干细胞定向分化为骨骼肌细胞和脂肪细胞的过程及其调控机制,并重点分析了关键调控因子PRDM16(PR domain-containing16)和骨形态发生蛋白(bone morphogenetic proteins,BMPs)在骨髓间充质干细胞成肌和成脂分化中的作用.     

肌源干细胞及其应用研究进展

研究证实,肌肉中存在2种类型的干细胞,即肌卫星细胞和多能干细胞,后者又可分为不同的细胞亚群。这些细胞群表现出自我更新能力和多潜能性,可分化为血细胞、成骨细胞、神经细胞等不同胚层的组织细胞。由于肌源干细胞具有治疗包括骨骼肌和心肌在内的肌肉疾病的可能性,并且潜在地可促进其他组织,如骨和软骨的再生和愈合,因此近几年来的相关研究取得很大进展。     

骨骼肌卫星细胞生物学特性及临床应用前景

骨骼肌卫星细胞是位于肌细胞膜和基膜之间的具有增殖和分化潜力的生肌干细胞,对于出生后骨骼肌的生长、再生修复和维持具有重要的意义.主要对卫星细胞的含量与分布、细胞标志、可塑性和不均一性等生物学特性做了综述,最后展望了卫星细胞移植在临床上的应用前景.     

骨髓间充质干细胞促进皮肤创伤愈合的作用机制及临床应用

皮肤是人体面积最大的器官,不同来源的损伤可使皮肤正常结构遭到破坏,皮肤创面修复过程失衡,从而导致皮肤愈合缓慢或畸形愈合,损害皮肤正常功能。骨髓间充质干细胞因其易获取、体外培养技术简单、低免疫原性、旁分泌、高度自我复制能力及多向分化潜能等特点而使其具有独特的优越性。已有研究表明骨髓间充质干细胞(BMSC)可通过多种复杂机制实现其促进皮肤创面愈合的作用,其趋化性可使BMSC向损伤部位迁移,并在局部分化为多种皮肤细胞、皮肤附属器细胞以及血管内皮细胞,促进皮肤的再生,通过抑制免疫细胞的生物学活性来发挥免疫调节作用。此外,BMSC可以分泌多种重要的生物活性因子,起到抗炎、促进新血管形成、抗纤维化及瘢痕形成、加快伤口愈合等作用。目前,BMSC已运用于多种类型皮肤损伤的临床治疗以及组织工程和再生医学中,且已取得了一定成果。本文主要就骨髓间充质干细胞的生物学特性、促进皮肤创伤愈合的作用机制及其临床应用进行了综述。     

肌卫星细胞研究进展

骨骼肌中的卫星细胞,长期以来就被认为是出生后骨骼肌生长、修复和维持的单能成肌干细胞。近年研究发现,卫星细胞与内皮细胞共同起源于胚胎血管祖细胞,且成年骨骼肌中存在多能干细胞,这些肌源多能干细胞在适当的微环境中具有多向分化潜能。这将为治疗包括帕金森病在内的多种临床退行性疾病提供自体干细胞的新来源。本文对肌卫星细胞的起源、增殖和成肌分化的分子调节机制,以及肌卫星细胞的多能干细胞潜能等方面的研究进展进行了综述。     

Wnt信号通路在骨骼肌损伤修复过程中的作用及机制研究CSCD

Wnt信号通路分为经典Wnt信号通路和非经典Wnt信号通路,而非经典Wnt信号通路又可分为Wnt/Ca^(2+)信号通路、Wnt/PCP信号通路和Wnt/PI3K信号通路。经典Wnt信号通路的恰当激活可有效抑制Notch信号通路,促进成肌分化和肌管融合。但经典Wnt信号通路过早或持续性激活,可通过调节多种细胞因子的表达,加重损伤骨骼肌纤维化,损害骨骼肌再生。而Wnt7a通过多条非经典Wnt信号通路刺激肌卫星细胞扩增、迁移,促进骨骼肌损伤修复,并能激活Akt/mTOR信号通路而诱导肌纤维肥大。     

间充质干细胞在炎症调节中的研究进展

间充质干细胞是一种具有多向分化潜能的成体干细胞,它不仅能促进损伤组织的再生与修复,还拥有良好的免疫调节能力,通过调控免疫细胞的增殖、分化和功能状态,调节炎症因子水平,对于各种炎症相关疾病具有很好的应用前景。该文就间充质干细胞的免疫调节能力的最新进展作一简要阐述,并介绍其在临床前试验的研究结果。     

脐血干细胞向不同体细胞分化的研究进展

脐血干细胞是一种具有多分化潜能的原始细胞,具备自我更新和增殖的能力,并能在特定因素的影响或诱导下,向多种细胞或组织分化。脐血来源的间充质干细胞不但可以分化为骨、脂肪和软骨,还可以转变成带有神经、肝脏及骨骼肌特异标记的细胞,并且具有应用到组织损伤修复、基因治疗载体和造血干细胞共移植等方面的潜力。旨在对于脐血干细胞在一定条件下分化为多种细胞研究进展进行综述。     

Signals from damaged but not undamaged skeletal muscle induce myogenic differentiation of rat bone-marrow-derived mesenchymal stem cells

The regenerative capacity of skeletal muscle has been usually attributed to resident satellite cells, which, upon activation by local or distant stimuli, initiate a myogenic differentiation program. Although recent studies have revealed that bone-marrow-derived progenitor cells may also participate in regenerative myogenesis, the signals and mechanisms involved in this process have not been elucidated. This study was designed to investigate whether signals from injured rat skeletal muscle were competent to induce a program of myogenic differentiation in expanded cultures of rat bone-marrow-derived mesenchymal stem cells (MSC). We observed that the incubation of MSC with a conditioned medium prepared from chemically damaged but not undamaged muscle resulted in a time-dependent change from fibroblast-like into elongated multinucleated cells, a transient increase in the number of MyoD positive cells, and the subsequent onset of myogenin, alpha-actinin, and myosin heavy chain expression. These results show that damaged rat skeletal muscle is endowed with the capacity to induce myogenic differentiation of bone-marrow-derived mesenchymal progenitors.     

Stem cell based therapy for skeletal muscle diseases

The use of stem cells to repair and replace damaged skeletal muscle cells in chronic, debilitating muscle diseases such as the muscular dystrophies holds great promise. Different stem cell populations, both of embryonic and adult origin display the potential to generate skeletal muscle cells and have been studied in animal models of muscular dystrophy. These include muscle derived satellite cells; bone marrow derived mesenchymal stem cells, muscle or bone marrow side population cells, circulating CD133+ cells and cells derived from blood vessel walls such as mesoangioblasts or pericytes. The design of effective stem cell based therapies requires a detailed understanding of the molecules and signaling pathways which determine myogenic lineage commitment and differentiation. We discuss the great strides that have been made in delineating these pathways and how a better understanding of muscle stem cell biology has the potential to lead to more effective stem cell based therapies for skeletal muscle regeneration for devastating muscle diseases.     

Cellular and molecular basis of skeletal muscle hystogenesis

The molecular basis of development and regeneration of skeletal muscles are reviewed. A model of parent-progeny relationships of mature animals?? skeletal muscles is proposed. Different cellular populations that contribute to myogenesis in vivo and in vitro are described. Both well-known typical cellular sources for muscle regeneration (satellite cells, muscle derived stem cells) and alternative cellular sources (CD133+ cells, pericytes, SP-cells from muscles and from bone marrow, mesangioblasts, embryonic stem cells and mesenchymal stromal cells) are presented. Moreover, some evidence for the existence of ectopic myogenic precursors in nonmuscle tissues is given.     

Mac-1(low) early myeloid cells in the bone marrow-derived SP fraction migrate into injured skeletal muscle and participate in muscle regeneration

Recent studies have shown that bone marrow (BM) cells, including the BM side population (BM-SP) cells that enrich hematopoietic stem cells (HSCs), are incorporated into skeletal muscle during regeneration, but it is not clear how and what kinds of BM cells contribute to muscle fiber regeneration. We found that a large number of SP cells migrated from BM to muscles following injury in BM-transplanted mice. These BM-derived SP cells in regenerating muscles expressed different surface markers from those of HSCs and could not reconstitute the mouse blood system. BM-derived SP/Mac-1(low) cells increased in number in regenerating muscles following injury. Importantly, our co-culture studies with activated satellite cells revealed that this fraction carried significant potential for myogenic differentiation. By contrast, mature inflammatory (Mac-1(high)) cells showed negligible myogenic activities. Further, these BM-derived SP/Mac-1(low) cells gave rise to mononucleate myocytes, indicating that their myogenesis was not caused by stochastic fusion with host myogenic cells, although they required cell-to-cell contact with myogenic cells for muscle differentiation. Taken together, our data suggest that neither HSCs nor mature inflammatory cells, but Mac-1(low) early myeloid cells in the BM-derived SP fraction, play an important role in regenerating skeletal muscles.     

A new function of a previously isolated compound that stimulates activation and differentiation of myogenic precursor cells leading to efficient myofiber regeneration and muscle repair

Muscle repair following severe injury is slow and incomplete due to the limited regenerative capacity of muscles comprising the function. In this study, one pure compound structurally corresponding to triterpenoid, which can directly induce the activation, proliferation and maturation of quiescent satellite cells into myocytes in vitro, was isolated from Geum japonicum. The potential effect of this compound on myogenesis was further tested in repair of severe muscle injury. It was found that this compound could significantly stimulate the regenerative potential of the damaged muscle resulting in regeneration of myotubes and myotube bundles time-dependently replacing the damaged muscle tissues. This compound-mediated active regeneration of new myofibers repairing damaged muscles was probably due to its direct action on activation and proliferation of quiescent myogenic precursor cells and enhancement of their maturation into regenerating myotubes, as was demonstrated in our primary myogenic precursor cells culture experiments. The up-regulated expression of endogenous phospho-Akt1 in compound-treated myogenic precursor cells may also contribute to the process of myofiber regeneration and muscle repair probably via promoting myogenic cell survival capacity.     

Pax7-expressing satellite cells are indispensable for adult skeletal muscle regeneration

Distinct cell populations with regenerative capacity have been reported to contribute to myofibres after skeletal muscle injury, including non-satellite cells as well as myogenic satellite cells. However, the relative contribution of these distinct cell types to skeletal muscle repair and homeostasis and the identity of adult muscle stem cells remain unknown. We generated a model for the conditional depletion of satellite cells by expressing a human diphtheria toxin receptor under control of the murine Pax7 locus. Intramuscular injection of diphtheria toxin during muscle homeostasis, or combined with muscle injury caused by myotoxins or exercise, led to a marked loss of muscle tissue and failure to regenerate skeletal muscle. Moreover, the muscle tissue became infiltrated by inflammatory cells and adipocytes. This localised loss of satellite cells was not compensated for endogenously by other cell types, but muscle regeneration was rescued after transplantation of adult Pax7(+) satellite cells alone. These findings indicate that other cell types with regenerative potential depend on the presence of the satellite cell population, and these observations have important implications for myopathic conditions and stem cell-based therapeutic approaches.     

Skeletal muscle repair by adult human mesenchymal stem cells from synovial membrane

We have demonstrated previously that adult human synovial membrane-derived mesenchymal stem cells (hSM-MSCs) have myogenic potential in vitro (De Bari, C., F. Dell'Accio, P. Tylzanowski, and F.P. Luyten. 2001. Arthritis Rheum. 44:1928-1942). In the present study, we have characterized their myogenic differentiation in a nude mouse model of skeletal muscle regeneration and provide proof of principle of their potential use for muscle repair in the mdx mouse model of Duchenne muscular dystrophy. When implanted into regenerating nude mouse muscle, hSM-MSCs contributed to myofibers and to long term persisting functional satellite cells. No nuclear fusion hybrids were observed between donor human cells and host mouse muscle cells. Myogenic differentiation proceeded through a molecular cascade resembling embryonic muscle development. Differentiation was sensitive to environmental cues, since hSM-MSCs injected into the bloodstream engrafted in several tissues, but acquired the muscle phenotype only within skeletal muscle. When administered into dystrophic muscles of immunosuppressed mdx mice, hSM-MSCs restored sarcolemmal expression of dystrophin, reduced central nucleation, and rescued the expression of mouse mechano growth factor.     

The emerging biology of satellite cells and their therapeutic potential

Adult skeletal muscle contains an abundant and highly accessible population of muscle stem and progenitor cells called satellite cells. The primary function of satellite cells is to mediate postnatal muscle growth and repair. Owing to their availability and remarkable capacity to regenerate damaged muscle, satellite cells and their descendent myoblasts have been considered as powerful candidates for cell-based therapies to treat muscular dystrophies and other neuromuscular diseases. However, regenerative medicine in muscle repair requires a thorough understanding of, and the ability to manipulate, the molecular mechanisms that control the proliferation, self-renewal and myogenic differentiation of satellite cells. Here, we review the latest advances in our current understanding of the quiescence, activation, proliferation and self-renewal of satellite cells and the challenges in the development of satellite cell-based regenerative medicine.     

A new look at the origin, function, and "stem-cell" status of muscle satellite cells

Muscle satellite cells have long been considered a distinct myogenic lineage responsible for postnatal growth, repair, and maintenance of skeletal muscle. Recent studies in mice, however, have revealed the potential for highly purified hematopoietic stem cells from bone marrow to participate in muscle regeneration. Perhaps more significantly, a population of putative stem cells isolated directly from skeletal muscle efficiently reconstitutes the hematopoietic compartment and participates in muscle regeneration following intravenous injection in mice. The plasticity of muscle stem cells has raised important questions regarding the relationship between the muscle-derived stem cells and the skeletal muscle satellite cells. Furthermore, the ability of hematopoietic cells to undergo myogenesis has prompted new investigations into the embryonic origin of satellite cells. Recent developmental studies suggest that a population of satellite cells is derived from progenitors in the embryonic vasculature. Taken together, these studies provide the first evidence that pluripotential stem cells are present within adult skeletal muscle. Tissue-specific stem cells, including satellite cells, may share a common embryonic origin and possess the capacity to activate diverse genetic programs in response to environmental stimuli. Manipulation of such tissue-specific stem cells may eventually revolutionize therapies for degenerative diseases, including muscular dystrophy.     

Niche regulation of muscle satellite cell self-renewal and differentiation

Muscle satellite cells have been shown to be a heterogeneous population of committed myogenic progenitors and noncommitted stem cells. This hierarchical composition of differentiating progenitors and self-renewable stem cells assures the extraordinary regenerative capacity of skeletal muscles. Recent studies have revealed a role for asymmetric division in satellite cell maintenance and offer novel insights into the regulation of satellite cell function by the niche. A thorough understanding of the molecular regulation and cell fate determination of satellite cells and other potential stem cells resident in muscle is essential for successful stem cell-based therapies to treat muscular diseases.