骨折愈合中骨再生的生物学和生物力学

一、骨再生的生物学1.骨骼的生长和发育骨骼的生长和发育涉及很多细胞和组织的分化和增殖,虽然其过程复杂,却精确有序。在胚胎发育阶段,长骨先形成一个间充质细胞团块,然后软骨化形成软骨基质。随着发育的渐进,软骨细胞肥大,细胞外基质开始矿化,形成初级骨化中心。软骨细胞通过     

特殊理化微环境的构建及其在生物医学领域的应用

生物医学领域中的微环境是指在实质细胞周围参与组织细胞生理及病理过程的微小特殊区域,它对于调控细胞的运动、增殖、分化、分泌及代谢功能具有重要作用。本文在介绍体内微环境及其组成的基础上,重点阐述了体外微环境构建技术及其在生物医学领域的应用,展望了微环境生理作用机制研究的发展趋势。     

基质金属蛋白酶及其组织抑制剂研究进展

基质金属蛋白酶家族是细胞外基质降解过程中的重要酶类,组织金属蛋白酶抑制剂是基质金属蛋白酶的天然抑制物。研究证实,细胞外基质中基质金属蛋白酶及其组织抑制剂的失衡与多种病理机制有关,尤其与肿瘤的侵袭和转移密切相关。本就基质金属蛋白酶及其组织抑制剂的性质、结构以及功能进行了综述。     

细胞外基质对发育和细胞分化的调控

在生物体里除了细胞以外,还存在着非细胞成份的基质,可能对细胞起着支撑作用。直到五十年代,对细胞外基质的认识还很简单,只知道它是由胶原蛋白和胶体溶液组成的物质。经过四十多年的研究,现在已经知道细胞外基质(extracellular matrix ECM)是由糖蛋白、蛋白多糖、糖氨聚糖等生物大分子(如胶原蛋白、纤维蛋白等等)所组成。这些分子相互交联,形成精细复杂的网状结构,存在于细胞外的微环境里。在受精卵第一次分裂形成的两个裂球之间,就发现有ECM成份的存在,并且在随     

再生调控的开关:组织再生增强子的研究进展

再生是组织发生损伤后恢复原有形态和功能的过程。不同脊椎动物的再生能力差异很大,硬骨鱼和两栖动物再生能力很强,而哺乳动物的再生能力极其有限。不同物种再生能力的差异很可能不是由于再生特异基因在进化过程中丢失造成的,相反,调控元件在组织损伤时的激活与否可能是决定再生成功与否的开关。增强子是一种顺式作用调控元件,对于精确调控基因表达必不可少。目前已经在多种模式生物中鉴定出了多个组织再生增强子,并报道了这些元件在组织再生中的关键作用。这篇综述将重点介绍增强子在组织再生中的重要调控作用,组织再生增强子的预测和鉴定,以及组织再生增强子在损伤时被激活的具体机制。     

TGF-β对肿瘤微环境中免疫监视及细胞外基质的调控作用

转化生长因子β(transforming growth factorβ,TGF-β)是一种多功能的细胞因子,能够调控细胞增殖、分化、黏附、迁移及凋亡等行为,在胚胎发育过程和成体组织稳态维持中发挥重要的作用。而在许多疾病状态下,特别是在癌症中,TGF-β不仅能够影响肿瘤细胞的增殖与转移,其对于肿瘤微环境的调控与塑造也受到越来越多的关注。肿瘤微环境是指肿瘤在发生和发展过程中所处的内环境,由肿瘤细胞本身、相邻正常组织中的间质细胞,以及这些细胞所释放的众多细胞因子等共同组成。肿瘤微环境是肿瘤发展的重要机制,也是肿瘤临床治疗领域亟待探索的关键问题。TGF-β是调节肿瘤微环境组成和功能的主要参与者之一。在本综述中,将着重讨论TGF-β对于肿瘤微环境中的免疫监视机制及肿瘤细胞外基质的主要影响。即TGF-β对于构成先天性和获得性抗肿瘤免疫应答的各种类群的免疫细胞具有广泛的调控作用,从而削弱宿主的肿瘤免疫监视功能。同时,TGF-β通过促进肿瘤相关成纤维细胞的产生,以及肿瘤细胞外基质的纤维化,有助于肿瘤的恶变和转移。此外,还介绍了通过阻断肿瘤微环境中TGF-β信号通路进行肿瘤治疗的主要策略及独特优势。而未来进一步解析TGF-β信号在肿瘤微环境中的复杂调控作用,并建立有效的靶向干预方法对于开发高效的抗肿瘤药物具有重要的意义。     

尿源干细胞在泌尿生殖系统再生领域的研究进展

近年来,随着尿源干细胞成功从尿液中提取,人们一直在探究其在人体各系统再生领域中的应用,尤其在泌尿生殖系统再生领域的研究较多。目前文献报道可见,尿源干细胞在肾脏、输尿管、膀胱、尿道和男性生殖器官等泌尿生殖系统的再生领域展现出一定的组织重建及修复能力,其应用前景广阔,本文就尿源干细胞在泌尿生殖系统再生领域的研究进展作一述评。     

微流控技术对细胞微环境的模拟及应用研究

细胞微环境是一个多因素组成的、时空可变的复杂集合,对细胞的行为和功能发挥起着决定性作用。但传统的细胞生物学研究方法很难在体外为细胞提供这样一个复杂的、微尺度的生长环境,致使许多体外研究结果与在体情况相差甚远。近年来,微流控技术与细胞培养技术的结合为细胞微环境的模拟和控制提供了可能。文章通过提炼微环境的重要参数及其特征,介绍微流控技术是如何满足这些参数的需求,探讨了微流控技术在体外模拟细胞微环境的可行性,并总结了近年来该技术在微环境体外模拟研究中取得的成果,对微流控技术在细胞微环境构建中的发展方向和应用前景进行了展望。     

结缔组织生成和肿瘤

肿瘤的发生并不只是由肿瘤细胞本身恶化引起的,肿瘤基质也发挥了非常重要的作用,肿瘤发生是肿瘤细胞和围绕它的肿瘤基质相互作用的产物。肿瘤细胞可以通过各种途径激活与其相邻的间质,促进成纤维细胞的增生、细胞外基质的沉积、免疫细胞浸润和血管生成,这种现象被称为结缔组织生成。结缔组织生成形成了一个支持肿瘤发展的微环境,通过多种途径促进了肿瘤的发生、发展和转移。针对结缔组织生成进行肿瘤治疗可以为肿瘤的临床治疗提供新的思路。     

结缔组织生成和肿瘤

肿瘤的发生并不只是由肿瘤细胞本身恶化引起的,肿瘤基质也发挥了非常重要的作用,肿瘤发生是肿瘤细胞和围绕它的肿瘤基质相互作用的产物。肿瘤细胞可以通过各种途径激活与其相邻的间质,促进成纤维细胞的增生、细胞外基质的沉积、免疫细胞浸润和血管生成,这种现象被称为结缔组织生成。结缔组织生成形成了一个支持肿瘤发展的微环境,通过多种途径促进了肿瘤的发生、发展和转移。针对结缔组织生成进行肿瘤治疗可以为肿瘤的临床治疗提供新的思路。     

Extracellular Vesicles in chondrogenesis and Cartilage regeneration

Extracellular vesicles (EVs), mainly exosomes and microvesicles, are bilayer lipids containing biologically active information, including nucleic acids and proteins. They are involved in cell communication and signalling, mediating many biological functions including cell growth, migration and proliferation. Recently, EVs have received great attention in the field of tissue engineering and regenerative medicine. Many in vivo and in vitro studies have attempted to evaluate the chondrogenesis potential of these microstructures and their roles in cartilage regeneration. EVs derived from mesenchymal stem cells (MSCs) or chondrocytes have been found to induce chondrocyte proliferation and chondrogenic differentiation of stem cells in vitro. Preclinical studies have shown that exosomes derived from MSCs have promising results in cartilage repair and in cell-free therapy of osteoarthritis. This review will focus on the in vitro and in vivo chondrogenesis and cartilage regeneration of EVs as well as their potential in the treatment of osteoarthritis.     

Role of hypoxia preconditioning in therapeutic potential of mesenchymal stem-cell-derived extracellular vesicles

The use of mesenchymal stem-cells (MSC) in cell therapy has received considerable attention because of their properties. These properties include high expansion and differentiation in vitro, low immunogenicity, and modulation of biological processes, such as inflammation, angiogenesis and hematopoiesis. Curiously, the regenerative effect of MSC is partly due to their paracrine activity. This has prompted numerous studies, to investigate the therapeutic potential of their secretome in general, and specifically their extracellular vesicles (EV). The latter contain proteins, lipids, nucleic acids, and other metabolites, which can cause physiological changes when released into recipient cells. Interestingly, contents of EV can be modulated by preconditioning MSC under different culture conditions. Among them, exposure to hypoxia stands out; these cells respond by activating hypoxia-inducible factor (HIF) at low O₂ concentrations. HIF has direct and indirect pleiotropic effects, modulating expression of hundreds of genes involved in processes such as inflammation, migration, proliferation, differentiation, angiogenesis, metabolism, and cell apoptosis. Expression of these genes is reflected in the contents of secreted EV. Interestingly, numerous studies show that MSC-derived EV conditioned under hypoxia have a higher regenerative capacity than those obtained under normoxia. In this review, we show the implications of hypoxia responses in relation to tissue regeneration. In addition, hypoxia preconditioning of MSC is being evaluated as a very attractive strategy for isolation of EV, with a high potential for clinical use in regenerative medicine that can be applied to different pathologies.     

Multiplexed targeting of microRNA in stem cell-derived extracellular vesicles for regenerative medicine

Regenerative medicine is a research field that develops methods to restore damaged cell or tissue function by regeneration, repair or replacement. Stem cells are the raw material of the body that is ultimately used from the point of view of regenerative medicine, and stem cell therapy uses cells themselves or their derivatives to promote responses to diseases and dysfunctions, the ultimate goal of regenerative medicine. Stem cell-derived extracellular vesicles (EVs) are recognized as an attractive source because they can enrich exogenous microRNAs (miRNAs) by targeting pathological recipient cells for disease therapy and can overcome the obstacles faced by current cell therapy agents. However, there are some limitations that need to be addressed before using miRNA-enriched EVs derived from stem cells for multiplexed therapeutic targeting in many diseases. Here, we review various roles on miRNA-based stem cell EVs that can induce effective and stable functional improvement of stem cell-derived EVs. In addition, we introduce and review the implications of several miRNA-enriched EV therapies improved by multiplexed targeting in diseases involving the circulatory system and nervous system. This systemic review may offer potential roles for stem cell-derived therapeutics with multiplexed targeting.     

Potential application of biomimetic exosomes in cardiovascular disease: focused on ischemic heart disease

Cardiovascular disease, especially ischemic heart disease, is a major cause of mortality worldwide. Cardiac repair is one of the most promising strategies to address advanced cardiovascular diseases. Despite moderate improvement in heart function via stem cell therapy, there is no evidence of significant improvement in mortality and morbidity beyond standard therapy. The most salutary effect of stem cell therapy are attributed to the paracrine effects and the stem cell-derived exosomes are known as a major contributor. Hence, exosomes are emerging as a promising therapeutic agent and potent biomarkers of cardiovascular disease. Furthermore, they play a role as cellular cargo and facilitate intercellular communication. However, the clinical use of exosomes is hindered by the absence of a standard operating procedures for exosome isolation and characterization, problems related to yield, and heterogeneity. In addition, the successful clinical application of exosomes requires strategies to optimize cargo, improve targeted delivery, and reduce the elimination of exosomes. In this review, we discuss the basic concept of exosomes and stem cell-derived exosomes in cardiovascular disease, and introduce current efforts to overcome the limitations and maximize the benefit of exosomes including engineered biomimetic exosomes.     

Regenerative medicine's historical roots in regeneration, transplantation, and translation

Regenerative medicine is not new; it has not sprung anew out of stem cell science as has often been suggested. There is a rich history of study of regeneration, of development, and of the ways in which understanding regeneration advances study of development and also has practical and medical applications. This paper explores the history of regenerative medicine, starting especially with T.H. Morgan in 1901 and carrying through the history of transplantation research in the 20th century, to an emphasis on translational medicine in the late 20th century.     

Mesenchymal stem cells for cartilage regeneration in dogs

Articular cartilage damage and osteoarthritis (OA) are common orthopedic diseases in both humans and dogs. Once damaged, the articular cartilage seldom undergoes spontaneous repair because of its avascular, aneural, and alymphatic state, and the damage progresses to a chronic and painful situation. Dogs have distinctive characteristics compared to other laboratory animal species in that they share an OA pathology with humans. Dogs can also require treatment for naturally developed OA;therefore, effective treatment methods for OA are desired in veterinary medicine as well as in human medicine. Recently, interest has grown in regenerative medicine that includes the use of mesenchymal stem cells (MSCs). In cartilage repair, MSCs are a promising therapeutic tool due to their self-renewal capacity, ability to differentiate into cartilage, potential for trophic factor production, and capacity for immunomodulation. The MSCs from dogs (canine MSCs;cMSCs) share various characteristics with MSCs from other animal species, but they show some deviations, particularly in their differentiation ability and surface epitope expression. In vivo studies of cMSCs have demonstrated that intraarticular cMSC injection into cartilage lesions results in excellent hyaline cartilage regeneration. In clinical situations, cMSCs have shown great therapeutic effects, including amelioration of pain and lameness in dogs suffering from OA. However, some issues remain, such as a lack of regulations or guidelines and a need for unified methods for the use of cMSCs. This review summarizes what is known about cMSCs, including their in vitro characteristics, their therapeutic effects in cartilage lesion treatment in preclinical in vivo studies, their clinical efficacy for treatment of naturally developed OA in dogs, and the current limitations of cMSC studies.     

Protein-engineered biomaterials: Nanoscale mimics of the extracellular matrix

Background

Traditional materials used as in vitro cell culture substrates are rigid and flat surfaces that lack the exquisite nano- and micro-scale features of the in vivo extracellular environment. While these surfaces can be coated with harvested extracellular matrix (ECM) proteins to partially recapitulate the bio-instructive nature of the ECM, these harvested proteins often exhibit large batch-to-batch variability and can be difficult to customize for specific biological studies. In contrast, recombinant protein technology can be utilized to synthesize families of 3 dimensional protein-engineered biomaterials that are cyto-compatible, reproducible, and fully customizable.

Scope of Review

Here we describe a modular design strategy to synthesize protein-engineered biomaterials that fuse together multiple repeats of nanoscale peptide design motifs into full-length engineered ECM mimics.

Major Conclusions

Due to the molecular-level precision of recombinant protein synthesis, these biomaterials can be tailored to include a variety of bio-instructional ligands at specified densities, to exhibit mechanical properties that match those of native tissue, and to include proteolytic target sites that enable cell-triggered scaffold remodeling. Furthermore, these biomaterials can be processed into forms that are injectable for minimally-invasive delivery or spatially patterned to enable the release of multiple drugs with distinct release kinetics.

General significance

Given the reproducibility and flexibility of these protein-engineered biomaterials, they are ideal substrates for reductionist biological studies of cell–matrix interactions, for in vitro models of physiological processes, and for bio-instructive scaffolds in regenerative medicine therapies.This article is part of a Special Issue entitled Nanotechnologies - Emerging Applications in Biomedicine.     

日本细胞治疗监管双轨制的经验及启示 *

随着生命科学技术的发展,细胞治疗创新性理论、技术和临床研究不断涌现,我国细胞治疗正处于一个良好的发展时期,监管成了推动其产业化发展的不可或缺环节。近年来,国家卫生健康委和国家食药监总局先后出台一系列政策规范监管,然而细胞治疗临床研究与临床应用按照药品监管还是技术监管、监管主体和审评标准等问题还没有清晰详细的规定与解释。梳理和总结了日本细胞治疗监管双轨制的基本内容,总结其监管的特色,为我国细胞治疗监管的职责界定提出政策建议。