Enhanced in vivo survival of Schwann cells by a synthetic oxygen carrier promotes sciatic nerve regeneration and functional recovery

Local hypoxia in the early stages of peripheral nerve injury is a challenge for axonal regeneration. To address this issue, perfluorotributylamine (PFTBA)‐based oxygen carrying fibrin hydrogel was prepared and injected into Schwann cell (SC)‐seeded collagen‐chitosan conduits to increase oxygen supply to SCs within the conduits. The conduit containing PFTBA‐SC gel was then applied to bridge a 15‐mm sciatic nerve defect in rats. It was observed that most of the GFP‐labeled SCs initially seeded in the PFTBA hydrogel remained alive for approximately 28 days after their in vivo implantation. The number of SCs was significantly higher in the PFTBA‐SC scaffold than that in the SC scaffold without PFTBA. In addition, nerve regeneration and functional recovery were examined after nerve injury repair. We found that the PFTBA‐SC scaffold was capable of promoting axonal regeneration and remyelination of the regenerated axons. Further studies showed the PFTBA‐SC scaffold was able to accelerate the recovery of motor and sensory function of the regenerating nerves. Electrophysiological analysis showed area under the curve of compound muscle action potential and nerve conduction velocity were also improved, and gastrocnemius muscle atrophy was partially reversed by PFTBA‐SC scaffold. Furthermore, microvessel density analysis showed PFTBA‐SC composites were beneficial for microvascular growth, which provided sustained oxygen for regenerating nerve in the later stages of nerve regeneration. In conclusion, enhanced survival of SCs by PFTBA is capable of promoting sciatic nerve regeneration and functional recovery, which provides a new avenue for achieving better functional recovery in the treatment of peripheral nerve injuries. Copyright © 2016 John Wiley & Sons, Ltd.     

MicroRNA‐132 directs human periodontal ligament‐derived neural crest stem cell neural differentiation

Neurogenesis is the basis of stem cell tissue engineering and regenerative medicine for central nervous system (CNS) disorders. We have established differentiation protocols to direct human periodontal ligament‐derived stem cells (PDLSCs) into neuronal lineage, and we recently isolated the neural crest subpopulation from PDLSCs, which are pluripotent in nature. Here, we report the neural differentiation potential of these periodontal ligament‐derived neural crest stem cells (NCSCs) as well as its microRNA (miRNA) regulatory mechanism and function in NCSC neural differentiation. NCSCs, treated with basic fibroblast growth factor and epidermal growth factor‐based differentiation medium for 24 days, expressed neuronal and glial markers (βIII‐tubulin, neurofilament, NeuN, neuron‐specific enolase, GFAP, and S100) and exhibited glutamate‐induced calcium responses. The global miRNA expression profiling identified 60 upregulated and 19 downregulated human miRNAs after neural differentiation, and the gene ontology analysis of the miRNA target genes confirmed the neuronal differentiation‐related biological functions. In addition, overexpression of miR‐132 in NCSCs promoted the expression of neuronal markers and downregulated ZEB2 protein expression. Our results suggested that the pluripotent NCSCs from human periodontal ligament can be directed into neural lineage, which demonstrate its potential in tissue engineering and regenerative medicine for CNS disorders.     

Regenerative effects of human embryonic stem cell‐derived neural crest cells for treatment of peripheral nerve injury

Surgical intervention is the current gold standard treatment following peripheral nerve injury. However, this approach has limitations, and full recovery of both motor and sensory modalities often remains incomplete. The development of artificial nerve grafts that either complement or replace current surgical procedures is therefore of paramount importance. An essential component of artificial grafts is biodegradable conduits and transplanted cells that provide trophic support during the regenerative process. Neural crest cells are promising support cell candidates because they are the parent population to many peripheral nervous system lineages. In this study, neural crest cells were differentiated from human embryonic stem cells. The differentiated cells exhibited typical stellate morphology and protein expression signatures that were comparable with native neural crest. Conditioned media harvested from the differentiated cells contained a range of biologically active trophic factors and was able to stimulate in vitro neurite outgrowth. Differentiated neural crest cells were seeded into a biodegradable nerve conduit, and their regeneration potential was assessed in a rat sciatic nerve injury model. A robust regeneration front was observed across the entire width of the conduit seeded with the differentiated neural crest cells. Moreover, the up‐regulation of several regeneration‐related genes was observed within the dorsal root ganglion and spinal cord segments harvested from transplanted animals. Our results demonstrate that the differentiated neural crest cells are biologically active and provide trophic support to stimulate peripheral nerve regeneration. Differentiated neural crest cells are therefore promising supporting cell candidates to aid in peripheral nerve repair.     

Human dental pulp stem cells expressing STRO‐1, c‐kit and CD34 markers in peripheral nerve regeneration

Peripheral nerve injuries are a commonly encountered clinical problem and often result in long‐term functional defects. The application of stem cells able to differentiate in Schwann cell‐like cells in vitro and in vivo, could represent an attractive therapeutic approach for the treatment of nerve injuries. Further, stem cells sources sharing the same embryological origin as Schwann cells might be considered a suitable tool. The aim of this study was to demonstrate the ability of a neuroectodermal subpopulation of human STRO‐1⁺/c‐Kit⁺/CD34⁺ DPSCs, expressing P75^NTR, nestin and SOX‐10, to differentiate into Schwann cell‐like cells in vitro and to promote axonal regeneration in vivo, which led to functional recovery as measured by sustained gait improvement, in animal rat model of peripheral nerve injury. Transplanted human dental pulp stem cells (hDPSCs) engrafted into sciatic nerve defect, as revealed by the positive staining against human nuclei, showed the expression of typical Schwann cells markers, S100b and, noteworthy, a significant number of myelinated axons was detected. Moreover, hDPSCs promoted axonal regeneration from proximal to distal stumps 1 month after transplantation. This study demonstrates that STRO‐1⁺/c‐Kit⁺/CD34⁺ hDPSCs, associated with neural crest derivation, represent a promising source of stem cells for the treatment of demyelinating disorders and might provide a valid alternative tool for future clinical applications to achieve functional recovery after injury or peripheral neuropathies besides minimizing ethical issues. Copyright © 2016 John Wiley & Sons, Ltd.     

In vitro evaluation of gel‐encapsulated adipose derived stem cells: Biochemical cues for in vivo peripheral nerve repair

Adipose‐derived stem cells (ASC) are becoming one of the most exploited cells in peripheral nerve repair. They are fast‐growing and able to protect neurons from apoptosis; they can reduce post‐injury latency and the risk of muscle atrophy. This study evaluates laminin‐loaded fibrin gel as an ASC‐carrying scaffold for nerve repair. In vitro, ASC retained their proliferative activity but showed significant increase in proliferation rate when encapsulated in gels with low laminin concentrations (i.e., 1 μg/mL). We observed a linear decrease of ASC proliferation rate with increasing laminin concentration from 1 to 100 μg/mL. We next examined the effect of the ASC‐carrying fibrin gels on in vitro dorsal root ganglia (DRG) neurite extension, then in vivo sciatic nerve regeneration in adult rats. The ASC‐carrying gel was embedded in 15‐mm‐long, 1.5‐mm‐diameter polydimethylsiloxane regenerative conduits for in vivo evaluation. At 8‐week post implantation, robust regeneration was observed across the long gap. Taken together, these results suggest ASC‐carrying gels are a potential path to improve the efficacy of nerve regeneration through artificial guidance conduits and electrode nerve interfaces.     

干细胞：许旺细胞的新来源

背景：许旺细胞对神经系统损伤的修复与再生有着重要作用。然而,许旺细胞不易直接获取,使其在临床上的应用受到限制。目的：综述神经损伤及修复过程、许旺细胞的作用以及各种干细胞分化为许旺细胞的潜能。方法：使用计算机检索Pubmed数据库2000/2011有关许旺细胞参与神经损伤的修复、干细胞分化为许旺细胞验证及应用的文献,检索词为＂Schwann cells,nervous system,stem cells＂。排除重复性研究,对资料进行初审,并查看每篇文献及其引文。根据纳入标准,收集到29篇相关文献。结果与结论：许旺细胞通过分泌各种细胞因子和营养因子为受损的神经营造了适于修复与再生的微环境,从而促进轴突再生;同时通过增殖及分化等机制围绕新生轴突形成髓鞘。神经修复需要大量许旺细胞的参与,而许旺细胞不易直接获取。研究表明,各种干细胞,包括胚胎干细胞、间充质干细胞、神经嵴干细胞和嗅鞘细胞,能在一定诱导条件下分化为许旺细胞样细胞,为神经系统损伤的治疗带来了新的希望。其中,间充质干细胞的研究备受关注。     

Regenerative effect of adipose tissue‐derived stem cells transplantation using nerve conduit therapy on sciatic nerve injury in rats

This study proposed a biodegradable GGT nerve conduit containing genipin crosslinked gelatin annexed with tricalcium phosphate (TCP) ceramic particles for the regeneration of peripheral nerves. Cytotoxicity tests revealed that GGT‐extracts were non‐toxic and promoted proliferation and neuronal differentiation in the induction of stem cells (i‐ASCs) derived from adipose tissue. Furthermore, the study confirmed the effectiveness of a GGT/i‐ASCs nerve conduit as a guidance channel in the repair of a 10‐mm gap in the sciatic nerve of rats. At eight weeks post‐implantation, walking track analysis showed a significantly higher sciatic function index (SFI) (P < 0.05) in the GGT/i‐ASC group than in the autograft group. Furthermore, the mean recovery index of compound muscle action potential (CMAP) differed significantly between GGT/i‐ASCs and autograft groups (P < 0.05), both of which were significantly superior to the GGT group (P < 0.05). No severe inflammatory reaction in the peripheral nerve tissue at the site of implantation was observed in either group. Histological observation and immunohistochemistry revealed that the morphology and distribution patterns of nerve fibers in the GGT/i‐ASCs nerve conduits were similar to those of the autografts. These promising results achieved through a combination of regenerative cells and GGT nerve conduits suggest the potential value in the future development of clinical applications for the treatment of peripheral nerve injury. Copyright © 2012 John Wiley & Sons, Ltd.     

Induced pluripotent stem cells (iPSCs) as a new source of bone in reconstructive surgery: A systematic review and meta‐analysis of preclinical studies

It is now well established that regenerative medicine and stem cell therapy are the most promising approach to obtain full tissue regeneration by using various cell types including stem cells isolated from adult tissues, embryonic stem cells, and induced pluripotent stem cells (iPSCs). Recently, iPSCs have been successfully differentiated into osteoprogenitors to facilitate repair and regeneration of bone defects. Thus, the purpose of this systematic review and meta‐analysis is to summarize the articles published that assess the osteogenic potential of iPSCs in vitro and their ability to heal bone defects in reconstructive surgery. PICO questions were subjected to literature search in four different databases. Methodological and risk of bias assessment of the included in vitro and in vivo articles were performed. Grading of Recommendations Assessment, Development, and Evaluation approach was used to assess the quality of evidence for each outcome variable included in the systematic review. In vivo bone formation was selected as the primary outcome for meta‐analysis, and publication bias was explored using funnel plots. Initial literature search retrieved 4,772 studies, whereas only 70 articles included in the review. Yamanaka set was the commonly used reprogramming factor introduced with different vectors into the somatic cells. Several somatic cell sources have been used to successfully produce the iPSCs. iPSCs have osteogenic differentiation capacities and would be considered as a new source of stem cells that can be used in reconstructive surgery for bone regeneration.     

Application of marrow mesenchymal stem cell‐derived extracellular matrix in peripheral nerve tissue engineering

To advance molecular and cellular therapy into the clinic for peripheral nerve injury, modification of neural scaffolds with the extracellular matrix (ECM) of peripheral nerves has been established as a promising alternative to direct inclusion of support cells and/or growth factors within a neural scaffold, while cell‐derived ECM proves to be superior to tissue‐derived ECM in the modification of neural scaffolds. Based on the fact that bone marrow mesenchymal stem cells (BMSCs), just like Schwann cells, are adopted as support cells within a neural scaffold, in this study we used BMSCs as parent cells to generate ECM for application in peripheral nerve tissue engineering. A chitosan nerve guidance conduit (NGC) and silk fibroin filamentous fillers were respectively prepared for co‐culture with purified BMSCs, followed by decellularization to stimulate ECM deposition. The ECM‐modified NGC and lumen fillers were then assembled into a chitosan–silk fibroin‐based, BMSC‐derived, ECM‐modified neural scaffold, which was implanted into rats to bridge a 10 mm‐long sciatic nerve gap. Histological and functional assessments after implantation showed that regenerative outcomes achieved by our engineered neural scaffold were better than those achieved by a plain chitosan–silk fibroin scaffold, and suggested the benefits of BMSC‐derived ECM for peripheral nerve repair. Copyright © 2016 John Wiley & Sons, Ltd.     

Microparticles for controlled growth differentiation factor 6 delivery to direct adipose stem cell‐based nucleus pulposus regeneration

Currently, there is no effective long‐term treatment for intervertebral disc (IVD) degeneration, making it an attractive candidate for regenerative therapies. Hydrogel delivery of adipose stem cells (ASCs) in combination with controlled release of bioactive molecules is a promising approach to halt IVD degeneration and promote regeneration. Growth differentiation factor 6 (GDF6) can induce ASC differentiation into anabolic nucleus pulposus (NP) cells and hence holds promise for IVD regeneration. Here, we optimised design of novel poly(DL‐lactic acid‐co‐glycolic acid) (PLGA)–polyethylene glycol–PLGA microparticles to control GDF6 delivery and investigated effect of released GDF6 on human ASCs differentiation to NP cells. Recombinant human (rh)GDF6 was loaded into microparticles and total protein and rhGDF6 release assessed. The effect of microparticle loading density on distribution and gel formation was investigated through scanning electron microscopy. ASC differentiation to NP cells was examined after 14 days in hydrogel culture by quantitative polymerase chain reaction, histological, and immunohistochemical staining in normoxic and IVD‐like hypoxic conditions. RhGDF6 microparticles were distributed throughout gels without disrupting gelation and controlled rhGDF6 release over 14 days. Released GDF6 significantly induced NP differentiation of ASCs, with expression comparable with or exceeding media supplemented rhGDF6. Microparticle‐delivered rhGDF6 also up‐regulated sulphated glycosaminoglycan and aggrecan secretion in comparison with controls. In hypoxia, microparticle‐delivered rhGDF6 continued to effectively induce NP gene expression and aggrecan production. This study demonstrates the effective encapsulation and controlled delivery of rhGDF6, which maintained its activity and induced ASC differentiation to NP cells and synthesis of an NP‐like matrix suggesting suitability of microparticles for controlled growth factor release in regenerative strategies for treatment of IVD degeneration.     

Growth differentiation factor‐5 regulation of extracellular matrix gene expression in murine tendon fibroblasts

The synthesis and organization of extracellular matrix (ECM) of tendon, in resting and states of repair, are governed by fibroblasts. Growth differentiation factor‐5 (GDF‐5) may enhance the cellular response to tendon injury, thus improving the structural outcome of the regenerative tissue. This study was an attempt to identify potential mechanisms controlling the response of fibroblasts to injury and GDF‐5, in the pursuit of improved tissue regeneration. There were two sets of experiments. Isolated mice Achilles tendon fibroblasts were treated with different concentrations of rGDF‐5 (0–100 ng/ml) for 0–12 days in cell culture. The temporal effect of rGDF‐5 on ECM gene expression was analysed for type I collagen and aggrecan expression. Microarray and gene expression analysis were performed on cells treated with 100 ng/ml for 4 days. Forty‐five mice underwent bilateral mid‐substance Achilles tendon tenotomy and suture repair. Repair sites were injected with 10 µg rGDF‐5 or saline. Tendons were assessed histologically at 2, 4 and 6 weeks. Expression of ECM genes procollagen IX, aggrecan, matrix metalloproteinase 9 and fibromodulin were upregulated. Proinflammatory reaction genes were downregulated. rGDF‐5 led to an increase in total DNA, glycosaminoglycan (GAG) and hydroxyproline (OHP). The OHP:DNA ratio of fibroblast cultures was increased over all time points, with increased GAG:DNA at day 12. rGDF‐5 treatment showed improved collagen organization over controls. The results delineate the mode of action of rGDF‐5 at the cellular and gene level. rGDF‐5 could play a role in tendon repair and be used for future therapies that promote tendon healing. Copyright © 2010 John Wiley & Sons, Ltd.     

Functional collagen conduits combined with human mesenchymal stem cells promote regeneration after sciatic nerve transection in dogs

Numerous studies have focused on the development of novel and innovative approaches for the treatment of peripheral nerve injury using artificial nerve guide conduits. In this study, we attempted to bridge 3.5‐cm defects of the sciatic nerve with a longitudinally oriented collagen conduit (LOCC) loaded with human umbilical cord mesenchymal stem cells (hUC‐MSCs). The LOCC contains a bundle of longitudinally aligned collagenous fibres enclosed in a hollow collagen tube. Our previous studies showed that an LOCC combined with neurotrophic factors enhances peripheral nerve regeneration. However, it remained unknown whether an LOCC seeded with hUC‐MSCs could also promote regeneration. In this study, using various histological and electrophysiological analyses, we found that an LOCC provides mechanical support to newly growing nerves and functions as a structural scaffold for cells, thereby stimulating sciatic nerve regeneration. The LOCC and hUC‐MSCs synergistically promoted regeneration and improved the functional recovery in a dog model of sciatic nerve injury. Therefore, the combined use of an LOCC and hUC‐MSCs might have therapeutic potential for the treatment of peripheral nerve injury.     

Preferential tendon stem cell response to growth factor supplementation

Tendon injuries are increasingly prevalent around the world, accounting for more than 100 000 new clinical cases/year in the USA alone. Cell‐based therapies have been proposed as a therapeutic strategy, with recent data advocating the use of tendon stem cells (TSCs) as a potential cell source with clinical relevance for tendon regeneration. However, their in vitro expansion is problematic, as they lose their multipotency and change their protein expression profile in culture. Herein, we ventured to assess the influence of insulin‐like growth factor 1 (IGF‐1), growth and differentiation factor‐5 (GDF‐5) and transforming growth factor‐β1 (TGFβ1) supplementation in TSC culture. IGF‐1 preserved multipotency for up to 28 days. Upregulation of decorin and scleraxis expression was observed as compared to freshly isolated cells. GDF‐5 treated cells exhibited reduced differentiation along adipogenic and chondrogenic pathways after 28 days, and decorin, scleraxis and collagen type I expression was increased. After 28 days, TGFβ1 supplementation led to increased scleraxis, osteonectin and collagen type II expression. The varied responses to each growth factor may reflect their role in tendon repair, suggesting that: GDF‐5 promotes the transition of tendon stem cells towards tenocytes; TGFβ1 induces differentiation along several pathways, including a phenotype indicative of fibrocartilage or calcified tendon, common problems in tendon healing; and IGF‐1 promotes proliferation and maintenance of TSC phenotypes, thereby creating a population sufficient to have a beneficial effect. Copyright © 2014 John Wiley & Sons, Ltd.     

低强度脉冲超声波对细胞增殖及生物合成的影响

低强度脉冲超声波具有独特的生物学效应,在体外细胞及体内实验中研究发现能够调节细胞的增殖、促进胶原及非胶原蛋白的合成、影响细胞因子的分泌和诱导细胞分化作用,其在临床治疗活动中已经在骨折,放射性骨坏死的治疗中取得一定成效。本文综述了近年来在低强度脉冲超声波生物学效应研究的新进展。     

促红细胞生成素促进脊髓损伤大鼠移植神经干细胞存活和迁移

背景：如何有效促进移植入脊髓损伤组织内的神经干细胞存活和迁移,是目前神经修复研究的重点。目的：观察促红细胞生成素对脊髓损伤大鼠移植神经干细胞存活、增殖和迁移的影响。方法：将60只SD大鼠随机分为3组,均制备脊髓横断损伤模型。造模7d,神经干细胞移植组和促红细胞生成素组于脊髓损伤处移植BrdU标记的神经干细胞7μL（1×109L-1）,脊髓损伤对照组移植DMEM/F12培养基;促红细胞生成素组腹腔内注射促红细胞生成素5000U/kg,1次/d,连续注射7d,其余两组注射等量生理盐水。于细胞移植后8周取损伤脊髓组织。结果与结论：造模2周后,神经干细胞移植组和促红细胞生成素组BBB评分明显高于脊髓损伤对照组（P〈0.05）,造模4周后,促红细胞生成素组BBB评分明显高于神经干细胞移植组（P〈0.05）。免疫荧光染色显示促红细胞生成素组大鼠损伤脊髓组织BrdU阳性细胞数量及迁移距离均大于神经干细胞移植组（P〈0.05）。说明促红细胞生成素能促进损伤脊髓组织原位移植的神经干细胞的存活与迁移,加速神经功能修复。     

神经干细胞与运动性神经疾病

背景：神经干细胞以其所具有的多向分化潜能、自我更新、迁徙性、低免疫性等特点受到临床的广泛应用,但有关神经干细胞在运动医学领域用于防治运动性损伤等的研究成果不是很多。目的：旨在通过分析神经干细胞的生物学特性,探讨其在临床上的应用,为神经性疾病的预防和治疗提供理论依据。方法：应用计算机检索CNKI和PubMed数据库中1997-01/2010-10关于神经干细胞与运动性神经疾病的文章,在标题和摘要中以＂神经干细胞,运动医学,失神经肌萎缩,周围神经损伤＂或＂Neural Stem Cell,Sports Medicine,Denervation Muscle Atrophy,Peripheral Nerve Injury＂为检索词进行检索,选择文章内容与神经干细胞和运动性神经疾病相关,同一领域文献选择近期发表或发表在权威杂志上的文章,初检得到262篇文献,根据纳入标准选择31篇进行综述。结果与结论：神经干细胞以其多向分化潜能、自我维持和更新、低免疫原性、迁徙性和来源广泛等特点为其在治疗神经退行性病变、运动性骨骼肌失神经肌萎缩和促运动性周围神经损伤的再生等提供了较为广阔的应用前景,但由于基础性研究所限,对其作用机制、诱导分化、迁移等仍有待大量的实验研究予以证实。     

A laminin‐2‐derived peptide promotes early‐stage peripheral nerve regeneration in a dual‐component artificial nerve graft

The DLTIDDSYWYRI motif (Ln2‐P3) of human laminin‐2 has been reported to promote PC12 cell attachment through syndecan‐1; however, the in vivo effects of Ln2‐P3 have not been studied. In Schwann cells differentiated from skin‐derived precursors, the peptide was effective in promoting cell attachment and spreading in vitro. To examine the effects of Ln2‐P3 in peripheral nerve regeneration in vivo, we developed a dual‐component poly(p‐dioxanone) (PPD)/poly(lactic‐co‐glycolic acid) (PLGA) artificial nerve graft. The novel graft was coated with scrambled peptide or Ln2‐P3 and used to bridge a 10 mm defect in rat sciatic nerves. The dual‐component nerve grafts provided tensile strength comparable to that of a real rat nerve trunk. The Ln2‐P3‐treated grafts promoted early‐stage peripheral nerve regeneration by enhancing the nerve regeneration rate and significantly increased the myelinated fibre density compared with scrambled peptide‐treated controls. These findings indicate that Ln2‐P3, combined with tissue‐engineering scaffolds, has potential biomedical applications in peripheral nerve injury repair. Copyright © 2012 John Wiley & Sons, Ltd.     

干细胞在神经创伤修复中的应用

背景：干细胞具有很强的增矾和分化能力,已在神经组织损伤修复方面展示了不可估嚣的临床应用前景。但是,目前有关神经干细胞的组织来源、定向诱导分化、移植技术和神经功能修复的功能判定等方面尚存在诸多难题。目的：阐述干细胞在神经创伤修复中的应用研究进展。方法：检索干细胞在神经创伤修复应用中的相关研究文献,检索词为“干细胞（stem cell）,骨髓间充质干细胞（bonemarrowmesenchymalstemcells）,神经干细胞（neuralstem cell）,胚胎干细胞（embryonicstemcell）,脂肪干细胞（adipose-derivedstemcells）,脐血干细胞（umbilicalcordbloodstemcells）,成体干细胞（adultstemcells）,脑损伤／创伤性脑损伤（traumaticbraininjury）,脊髓损伤（spinalcordinjury）,神经创伤（traumaticnerveinjury）,生长因子（growthfactor）,修复（repair）”,语言分别设定为中文和英文,对骨髓间充质干细胞、神经干细胞、胚胎干细胞、脐血干细胞及脂肪干细胞在神经创伤修复中的应用研究进行深入分析。结果与结论：干细胞是一具有自我更新、高度增殖和多向分化潜能的特殊细胞,其最显著的生物学特性是既有自我更新的能力,又具有多向分化的潜能。日前,已经从许多组织或器官中成功地分离出,其中包括胚胎干细胞,造血干细胞和骨髓间质干细胞等。此外,还有近来研究渐多的神经干细胞、肌肉干细胞、成骨干细胞、内胚层干细胞及视网膜干细胞等。干细胞的多向分化潜能为神经创伤修复开辟了新的途径,其在脑损伤以及脊髓损伤后的神经修复以及功能重建的研究方面已取得很大的进展,被认为具有广阔的应用前景,与之相关的问题均有待于进一步的研究。