间充质干细胞特性与应用前景

间充质干细胞是中胚层发育的早期细胞,具备干细胞的基本特性。在发育的不同阶段和特定环境条件下,间充质干细胞可向骨、软骨、肌肉、神经、血管及血液细胞等多种方向分化。在成体的很多器官和组织中也存在着间充质干细胞,以备修复和再生所用。间充质干细胞易于体外培养,扩增迅速,可以分化为多种细胞,为干细胞生物工程提供了一个很好的种子细胞。在明确间充质干细胞生物学特性和分化的机制后,可在体外和体内将其定向诱导分化为多种细胞。间充质干细胞具有巨大的临床应用价值和科学研究价值。     

骨髓间充质干细胞及其临床应用研究进展

骨髓间充质干细胞因具有容易获得、容易体外培养增殖、长期培养的过程中始终保持多向分化的潜能、抗原性小、组织修复能力强等特征,使之成为干细胞研究领域的热点和前沿,并被认为是最有前途的组织工程种子细胞之一。以干细胞工程为代表的现代组织工程学为组织器官的修复与替代提供了一个崭新的领域,并将此领域扩展到细胞替代治疗、支持造血、基因治疗等更多方面。     

骨髓间充质干细胞在组织工程研究中的应用新进展

骨髓间充质干细胞又称为骨髓源性间充质干细胞,是指存在于骨髓基质细胞系统中的一类干细胞,具有高度稳定的体外扩增能力和多向分化潜能等特点。骨髓间充质干细胞因其取材方便,易于分离和培养,以及在适当条件下可诱导分化为皮肤、骨骼、内脏、血液、神经等多种组织细胞的独特优势,目前被广泛应用于药物开发、免疫调节、组织修复、器官重建等多个研究领域。近年来,骨髓间充质干细胞作为种子细胞在组织工程领域有着非常诱人的潜在应用前景。本文就骨髓间充质干细胞在组织工程学研究中应用的最新进展作一综述。     

诱导多能干细胞在组织工程修复关节软骨损伤的研究进展

关节软骨位于骨骼末端,主要起承重、减震和润滑关节的作用。由于缺乏血运,关节软骨损伤后难以自行修复。关节软骨损伤为临床常见疾病,目前尚无理想的方法促进其修复和再生,而以种子细胞、支架材料和细胞生长因子为基础的组织工程技术为关节软骨修复开辟了新道路。诱导多能干细胞(i PSC)作为软骨组织工程全新的种子细胞,与其他种子细胞相比,在软骨细胞移植及体外软骨组织和器官再造方面具有更广阔的应用前景。随着对i PSC的重编程机制、诱导方法、定向软骨分化条件以及临床应用安全性等研究的不断深入,其应用于临床的脚步将越来越近。     

利用脱细胞血管基质体外构建小口径组织工程血管

目的探讨利用犬的间充质干细胞诱导分化种子细胞,以异种脱细胞血管基质为基础体外构建小口径血管移植物。方法采用密度梯度离心和贴壁培养的方法从犬骨髓中分离出间充质干细胞并体外培养,诱导分化成内皮样细胞和平滑肌样细胞;采用非离子型去垢剂和胰蛋白酶去除猪颈动脉血管壁结构细胞,对脱细胞基质进行组织学、力学检测及孔隙率评估。在生物反应器内采用旋转种植的方法将犬骨髓间充质干细胞诱导的内皮样细胞种植到脱细胞基质上,体外构建小口径组织工程血管。结果犬的骨髓间充质干细胞体外能够定向诱导分化为平滑肌样细胞和内皮样细胞,可以作为血管组织工程的种子细胞。经过脱细胞处理后,光镜和电镜观察证实血管壁的细胞成分完全去除。具有良好的孔径和孔隙率。支架在生物力学、孔隙率等方面符合构建组织工程血管支架的要求。在生物反应器内剪切力条件下可以初步构建出组织工程血管。结论小口径血管移植物可以将间充质干细胞诱导种子细胞,以异种脱细胞血管支架作为基质,在搏动性生物反应器内培养的方法进行构建。     

成体干细胞在泌尿系统疾病修复与重建中的应用

干细胞是目前生命科学研究的热点方向。干细胞具有自我更新及定向分化的潜在能力。近年来,干细胞移植治疗在治疗压力性尿失禁和膀胱损伤方面已成为研究重点,不同来源的干细胞在治疗膀胱损伤已取得瞩目的研究成果。干细胞对阴茎勃起神经和海绵体血管内皮细胞起着修复保护作用。干细胞具有向多种谱系细胞转化的能力来治疗压力性尿失禁。干细胞移植为泌尿系统的神经肌肉疾病的修复重建提供了一条新途径,使认为不可修复的的神经肌肉疾病的结构修复和组织重建成为可能。干细胞包括脂肪干细胞(adipose-derived stem cells,ADSCs)、骨髓间充质干细胞(bone narrow mesenchymal stem,BMSCs)和肌源性干细胞(muscle-derived stem cell,MDSCs)等。组织工程学是一类交叉学科,主要包括综合细胞培养、材料构建和细胞种植等。组织工程技术为泌尿外科临床医师提供了一条修复乃至重建受损脏器的新思路。本文就利用干细胞作为种子细胞,对膀胱缺损、压力性尿失禁、勃起功能障碍泌尿系疾病的组织工程修复进行综述。     

诱导重编程的表观遗传调控研究进展

表观遗传调控是细胞命运变化与决定的重要基础之一。2006年,日本科学家山中伸弥发现通过4个转录因子Oct4、Sox2、Klf4和c-Myc可以将已经分化的体细胞逆转回与胚胎干细胞相似的多能性状态,获得诱导多能干细胞(induced pluripotent stem cells,i PSCs)。这种诱导重编程技术不仅是干细胞技术的一大突破,也提供了关键的体外模型用于研究细胞重编程的表观遗传机制。对该机制的深入理解将推动人类自由操纵细胞命运的进程,从而有望治疗各种因功能细胞、组织、器官缺失退化引发的疾病。从诱导重编程的表观遗传调控方向的研究进展出发,阐述通过诱导重编程发现的关键细胞命运转变表观调控机制,展望未来的主要研究目标。     

成体干细胞向类许旺细胞诱导分化研究进展

周围神经损伤修复的黄金标准是自体神经移植,但由于遗留供区部位感觉功能障碍及可供移植神经数量有限,致使该项技术在临床上的应用受到限制,组织工程学的发展为此提供了一种新的解决途径.许旺细胞是周围神经组织工程重要的种子细胞,在神经再生过程中发挥重要作用,移植许旺细胞修复周围神经损伤有广阔的应用前景,但异体移植常面临免疫排斥反应,这些均导致了许旺细胞作为周围神经组织工程的种子细胞在临床应用中受到限制.近年来,随着对具有自我更新和多向分化潜能的间充质干细胞的深入研究,为组织工程化人工神经种子细胞的发展提出新的思路,本文将各种成体干细胞作为许旺细胞的替代细胞的研究进展作一综述.     

脐带间充质干细胞牙向分化的可行性研究

再生医学近年来受到越来越多的重视。它开启了治疗由于老化,损伤及一些先天性缺陷所造成的缺损畸形的新途径。其临床应用已涉及到各种组织的修复,包括血液,皮肤,角膜,软骨和骨等。在口腔领域,目前治疗牙缺失主要依靠修复体,种植体和牙移植。然而这些方法都存在一定的缺陷。而通过再生医学的原理和方法实现牙再生治疗可以为机体提供有生命的,有功能的,相容性好的组织结构。种子细胞是牙再生的基础与关键。在牙再生研究中,牙髓间充质干细胞,牙乳头细胞,牙周膜间充质细胞,牙囊细胞及牙源性上皮细胞等牙源性干细胞常通过诱导分化为成釉细胞或成牙本质细胞来作为种子细胞应用,在临床上却难以获取,近来研究也有用骨髓间充质干细胞或脂肪间充质干细胞细胞等非牙源性干细胞者,但其牙向分化能力及分化调控机制还不明确。跻带间充质干细胞在新近的研究中较其它非牙源性干细胞表现出更大的优势,脐带间充质干细胞更原始、具有更高可塑性、更大扩增分化潜能。在此,本文就脐带间充质干细胞向牙细胞系分化的可能性做一论述,并对其可能实现的牙向分化给出可能的方法和策略,为牙再生种子细胞的选取提供新的思路。     

组织工程中应力对骨髓间充质干细胞分化为成骨细胞的影响

骨髓间充质干细胞具有自我复制、未分化的特点,并可在不同条件下分化为中胚层起源的多种细胞,是一种成体多能干细胞。就组织工程而言,良好的种子细胞是组织工程技术的关键,骨髓间充质干细胞的性质决定了其在骨组织工程领域中的重要地位。此外,骨骼系统属于机体的运动系统,承担体重是骨骼的重要功能之一;而且,人体内几乎所有的细胞都会受到力学因素的影响,故有必要研究力学因素对骨髓间充质干细胞诱导分化为成骨细胞的作用,为骨髓间充质干细胞的体外扩增、诱导分化及培养提供一种新途径。     

组蛋白乙酰化对成体干细胞生物学性状的影响

成体干细胞（adult stem cells,ASCs）是指存在于一种已经分化组织中的未分化细胞,它们可以再生修复损伤的组织和器官,是组织工程和细胞治疗的理想细胞。但是ASCs在体外扩增过程中容易发生自主分化和衰老,影响其在临床的广泛应用。组蛋白乙酰化作为表观遗传调节的重要机制,参与细胞分化、衰老及凋亡等众多细胞活动的调控。该文就组蛋白乙酰化对成体干细胞生物学性状的影响进行综述。     

Stem cells for osteoarticular and vascular tissue engineering

Tissue damages or loss of organs often result in structural and metabolic changes that can cause serious complications. The therapeutic objective of tissue engineering (TE) is to recreate, regenerate or restore function of damaged tissue. TE is based on the coalescence of three components: a scaffold or matrix from natural or synthetic origin biodegradable or not, reparative cells and signals (hypoxia, mechanical stress, morphogens…). Articular cartilage, bone and blood vessels are tissues for which TE has progressed significantly, from basic research to clinical trials. If biomaterials must exhibit different properties depending on the tissue to regenerate, the cellular component of TE is mostly represented by stem cells notably adult mesenchymal stem cells harvested from bone marrow or adipose tissue. In recent years, progress has been made in our understanding of the biological mechanisms that govern stem cell differentiation and in the development of materials with controlled physicochemical and biological properties. However, many technological barriers and regulations concerns have to be overcome before tissue engineering enters into the therapeutic arsenal of regenerative medicine. This review aims at highlighting the progress in the use of stem cells for engineering osteoarticular and vascular tissues.     

Stem cells and regenerative medicine

Stem cells have been defined as clonogenic cells that undergo both self-renewal and differentiation to more committed progenitors and functionally specialized mature cells. Of late years, stem cells have been identified in a variety of tissues of an adult body. Depending on the source, they have the potential to form one or more, or even all cell types of an organism. Stem cell research provided some outstanding contributions to our understanding of developmental biology and offered much hope for cell replacement therapies overcoming a variety of diseases. The establishment of human ES cell lines enabled us to generate all tissues we comprise. Recently, excitement has been evoked by the controversial evidence that adult stem cells have a much higher degree of developmental plasticity than previously imagined. More recently, the existence of multipotent somatic stem cells in bone marrow has been reported. Combined with these discoveries and achievements as well as the developing technologies, scientists are now trying to bring stem cell therapies to the clinic.     

成体干细胞的研究及潜在应用

成体干细胞(adultstemcells)存在于人和哺乳动物的多种成体中,具有自我更新和一定的分化潜能.现已从骨髓、软骨、血液、神经、肌肉、脂肪、皮肤、角膜缘、肝脏、胰腺等许多组织中获得干细胞,并在部分成体干细胞的体外分离培养、扩增及诱导分化等研究中取得突破性进展,发现部分成体干细胞具有预想不到的分化潜能.成体干细胞不仅是发育生物学研究的理想模型,而且是细胞移植治疗、人工组织或器官构建的种子细胞和基因治疗的理想载体细胞,因此,在揭示生命的本质和规律及再生医学中有十分广阔的应用前景.     

Nanomaterial scaffolds for stem cell proliferation and differentiation in tissue engineering

Tissue engineering is a clinically driven field and has emerged as a potential alternative to organ transplantation. The cornerstone of successful tissue engineering rests upon two essential elements: cells and scaffolds. Recently, it was found that stem cells have unique capabilities of self-renewal and multilineage differentiation to serve as a versatile cell source, while nanomaterials have lately emerged as promising candidates in producing scaffolds able to better mimic the nanostructure in natural extracellular matrix and to efficiently replace defective tissues. This article, therefore, reviews the key developments in tissue engineering, where the combination of stem cells and nanomaterial scaffolds has been utilized over the past several years. We consider the high potential, as well as the main issues related to the application of stem cells and nanomaterial scaffolds for a range of tissues including bone, cartilage, nerve, liver, eye etc. Promising in vitro results such as efficient attachment, proliferation and differentiation of stem cells have been compiled in a series of examples involving different nanomaterials. Furthermore, the merits of the marriage of stem cells and nanomaterial scaffolds are also demonstrated in vivo, providing early successes to support subsequent clinical investigations. This progress simultaneously drives mechanistic research into the mechanotransduction process responsible for the observations in order to optimize the process further. Current understanding is chiefly reported to involve the interaction of stem cells and the anchoring nanomaterial scaffolds by activating various signaling pathways. Substrate surface characteristics and scaffold bulk properties are also reported to influence not only short term stem cell adhesion, spreading and proliferation, but also longer term lineage differentiation, functionalization and viability. It is expected that the combination of stem cells and nanomaterials will develop into an important tool in tissue engineering for the innovative treatment of many diseases.     

Models of epithelial histogenesis

Epithelial tissues emerge from coordinated sequences of cell renewal, specialization and assembly. Like corresponding immature tissues, adult epithelial tissues are provided by stem cells which are responsible for tissue homeostasis. Advances in epithelial histogenesis has permitted to clarify several aspects related to stem cell identification and dynamics and to understand how stem cells interact with their environment, the so-called stem cell niche. The development and maintenance of epithelial tissues involves epithelial-mesenchymal signalling pathways and cell-matrix interactions which control target nuclear factors and genes. The tooth germ is a prototype for such inductive tissue interactions and provides a powerful experimental system for the study of genetic pathways during development. Clonogenic epithelial cells isolated from developing as well mature epithelial tissues has been used to engineer epithelial tissue-equivalents, e.g. epidermal constructs, that are used in clinical practise and biomedical research. Information on molecular mechanisms which regulate epithelial histogenesis, including the role of specific growth/differentiation factors and cognate receptors, is essential to improve epithelial tissue engineering.     

组织工程的突破与挑战——组织工程国家工程中心科研进展

组织工程技术已被普遍认为是解决组织、器官缺损修复与功能重建的有效手段,它的飞速发展依赖于细胞学、材料学、工程学、临床医学等多学科的交叉渗透.作为组织工程的三大核心,种子细胞、生物材料、组织构建各方面的突破,为组织工程技术的发展奠定了基础.组织工程国家工程中心近年来围绕上述核心开展了系列研究,通过研究胚胎干细胞、成体干细胞、同种异体干细胞、以及发育同源细胞替代的探索,为解决种子细胞来源问题提供了多种选择;生物支架材料的开发,为细胞增殖分化、组织再生提供理想的支持与空间,而生物反应器的开发与应用,进一步提高了组织构建技术,为促进组织的体外形成、重塑和功能成熟创造了条件.在此基础上,开展了大动物体内组织构建和缺损修复的研究,形成了以应用为目标的研究特色,并成功将部分技术应用于临床治疗.本文将对组织工程国家工程中心已有进展做简单介绍并对面临的挑战进行分析.     

“The Good into the Pot,the Bad into the Crop!”—A New Technology to Free Stem Cells from Feeder Cells

A variety of embryonic and adult stem cell lines require an intial co-culturing with feeder cells for non-differentiated growth, self renewal and maintenance of pluripotency. However for many downstream ES cell applications the feeder cells have to be considered contaminations that might interfere not just with the analysis of experimental data but also with clinical application and tissue engineering approaches. Here we introduce a novel technique that allows for the selection of pure feeder-freed stem cells, following stem cell proliferation on feeder cell layers. Complete and reproducible separation of feeder and embryonic stem cells was accomplished by adaptation of an automated cell selection system that resulted in the aspiration of distinct cell colonies or fraction of colonies according to predefined physical parameters. Analyzing neuronal differentiation we demonstrated feeder-freed stem cells to exhibit differentiation potentials comparable to embryonic stem cells differentiated under standard conditions. However, embryoid body growth as well as differentiation of stem cells into cardiomyocytes was significantly enhanced in feeder-freed cells, indicating a feeder cell dependent modulation of lineage differentiation during early embryoid body development. These findings underline the necessity to separate stem and feeder cells before the initiation of in vitro differentiation. The complete separation of stem and feeder cells by this new technology results in pure stem cell populations for translational approaches. Furthermore, a more detailed analysis of the effect of feeder cells on stem cell differentiation is now possible, that might facilitate the identification and development of new optimized human or genetically modified feeder cell lines.