Multipotent stem cells in human corneal stroma

Keratocytes of the corneal stroma secrete a specialized extracellular matrix essential for vision. These quiescent cells exhibit limited capacity for self-renewal and after cell division become fibroblastic, secreting nontransparent tissue. This study sought to identify progenitor cells for human keratocytes. Near the corneal limbus, stromal cells expressed ABCG2, a protein present in many adult stem cells. The ABCG2-expressing cell population was isolated as a side population (SP) by cell sorting after exposure to Hoechst 33342 dye. The SP cells exhibited clonal growth and continued to express ABCG2 and also PAX6, product of a homeobox gene not expressed in adult keratocytes. Cloned SP cells cultured in medium with fibroblast growth factor-2 lost ABCG2 and PAX6 expression and upregulated several molecular markers of keratocytes, including keratocan, aldehyde dehydrogenase 3A1, and keratan sulfate. Cloned corneal SP cells under chondrogenic conditions produced matrix staining with toluidine blue and expressed cartilage-specific markers: collagen II, cartilage oligomatrix protein, and aggrecan. Exposure of cloned SP cells to neurogenic culture medium upregulated mRNA and protein for glial fibrillary acidic protein, neurofilament protein, and beta-tubulin II. These results demonstrate the presence of a population of cells in the human corneal stroma expressing stem cell markers and exhibiting multipotent differentiation potential. These appear to be the first human cells identified with keratocyte progenitor potential. Further analysis of these cells will aid elucidation of molecular mechanisms of corneal development, differentiation, and wound healing. These cells may be a resource for bioengineering of corneal stroma and for cell-based therapeutics.     

Muscle-derived stem cells for tissue engineering and regenerative therapy

Skeletal muscle has been recognized as an essential source of progenitor or satellite cells, which are primarily responsible for muscle regeneration. Recently, muscle has also been identified as a valuable source of postnatal stem cells that appear to be distinct from satellite cells and possess the ability to differentiate into other cell lineages. These cells, named muscle-derived stem cells, possess a high myogenic capacity and effectively regenerate both skeletal and cardiac muscle. Remarkably, when genetically modified ex vivo to express growth factors, these cells can differentiate into osteogenic and chondrogenic lineages and have been shown to promote the repair of bone and cartilage. Muscle stem cell-based regenerative therapy and tissue engineering using ex vivo gene therapy, are promising approaches for the treatment of various musculoskeletal, cardiovascular, and urological disorders.     

Cell delivery in cardiac regenerative therapy

There is a growing interest in the clinical application of stem cells as a novel therapeutic approach for treatment of myocardial infarction and prevention of subsequent heart failure. Transplanted stem cells improve cardiac functions through multiple mechanisms, which include but are not limited to promoting angiogenesis, replacing dead cardiomyocytes, modulating cardiac remodeling. Most of the results obtained so far are exciting and very promising, spawning an increasing number of clinical trials recently. However, many problems still remain to be resolved such as the best delivery method for transplantation of cells to the injured myocardium and the issue of how to optimize the delivery of targeted cells is of exceptional clinical relevance. In this review, we focus on the different delivery strategies in cardiac regenerative therapy, as well as provide a brief overview of current clinical trials utilizing cell-based therapy in patients with ischemic heart disease.     

Multipotent stem cells from adult olfactory mucosa.

Multipotent stem cells are thought to be responsible for the generation of new neurons in the adult brain. Neurogenesis also occurs in an accessible part of the nervous system, the olfactory mucosa. We show here that cells from human olfactory mucosa generate neurospheres that are multipotent in vitro and when transplanted into the chicken embryo. Cloned neurosphere cells show this multipotency. Multipotency was evident without prior culture in vitro: cells dissociated from adult rat olfactory mucosa generate leukocytes when transplanted into bone marrow-irradiated hosts, and cells dissociated from adult mouse olfactory epithelium generated numerous cell types when transplanted into the chicken embryo. It is unlikely that these results can be attributed to hematopoietic precursor contamination or cell fusion. These results demonstrate the existence of a multipotent stem-like cell in the olfactory mucosa useful for autologous transplantation therapies and for cellular studies of disease.     

Multipotent adult germline stem cells and embryonic stem cells have similar microRNA profiles

Spermatogonial stem cells (SSCs) isolated from the adult mouse testis and cultured have been shown to respond to culture conditions and become pluripotent, so called multipotent adult germline stem cells (maGSCs). microRNAs (miRNAs) belonging to the 290 and 302 miRNA clusters have been previously classified as embryonic stem cell (ESC) specific. Here, we show that these miRNAs generally characterize pluripotent cells. They are expressed not only in ESCs but also in maGSCs as well as in the F9 embryonic carcinoma cell (ECC) line. In addition, we tested the time-dependent influence of different factors that promote loss of pluripotency on levels of these miRNAs in all three pluripotent cell types. Despite the differences regarding time and extent of differentiation observed between ESCs and maGSCs, expression profiles of both miRNA families showed similarities between these two cell types, suggesting similar underlying mechanisms in maintenance of pluripotency and differentiation. Our results indicate that the 290-miRNA family is connected with Oct-4 and maintenance of the pluripotent state. In contrast, members of the 302-miRNA family are induced during first stages of in vitro differentiation in all cell types tested. Therefore, detection of miRNAs of miR-302 family in pluripotent cells can be attributed to the proportion of spontaneously differentiating cells in cultures of pluripotent cells. These results are consistent with ESC-like nature of maGSCs and their potential as an alternative source of pluripotent cells from non-embryonic tissues.     

干细胞在心脏再生医学中的作用及中医药研究策略

背景：中医对心脏再生有其独特认识,但中医药介入干细胞与心脏再生医学还处于初步探索阶段。 目的：分析和总结干细胞与心脏再生相关的研究进展,对中医药如何介入心脏再生研究进行初步探讨。 方法：以关键词“stem cell”与 “cardiac regenerative medicine”检索PubMed数据库、关键词“干细胞”与“中医”检索CNKI中国期刊全文数据库2000/2010的相关文献,语言种类不限,对符合标准的文献证据进行综合提炼分析。保留其中44篇进行归纳总结。 结果与结论：分析表明干细胞应用于心脏再生医学的研究已广泛拓展,包括胚胎干细胞、骨髓干细胞、成体心脏干细胞等均显示了再生心肌的能力及其应用前景。中医对心脏再生的认识蕴含在阴阳观、五行母子规律及精气学说中。中医药要介入心脏再生医学,就需要对中医理论在心脏再生医学中的认识进行系统整理,深入挖掘中医复方,重视中药有效组分靶向干细胞及加强对有效方药作用机制的研究。     

Anti-HLA antibodies in regenerative medicine stem cell therapy

Research on stem cell therapies for regenerative medicine is progressing rapidly. Although the use of autologous stem cells is a tempting choice, there are several instances in which they are either defective or not available in due time. Allogenic stem cells derived from healthy donors presents a promising alternative. Whether autologous or allogenic, recent advances have proven that stem cells are not as immune privileged as they were thought. Therefore understanding the interactions of these cells with the recipient immune system is paramount to their clinical application. Transplantation of stem cells induces humoral as well as cellular immune response. This review focuses on the humoral response elicited by stem cells upon their administration and consequences on the survival and maintenance of the graft. Current transplantation identifies pre- and post-transplantation anti-HLA antibodies as immune rejection and cell signaling effectors. These two mechanisms are likely to operate similarly in the context of SC therapeutics. Ultimately this knowledge will help to propose novel strategies to mitigate the allogenic barriers. Immunogenetics selection of the donor cell and immunomonitoring are key factors to allow the implementation of regenerative stem cell in the clinics.     

Multipotent stem and progenitor cells of the olfactory epithelium

In recent decades, a wide spectrum of fetal and embryonic stem and progenitor cells were used for cell therapy of diseases of the central nervous system, but the olfactory glial ensheathing cells exhibited certain advantages due to their biological properties and capacity to stimulate regeneratory processes in spinal injury. The therapeutic effect of a heterogeneous complex of olfactory epithelial cells is more pronounced; apart from glial ensheathing cells, this complex includes fibroblasts, Schwann cells, stem and progenitor cells of this structure. The use of minimally invasive methods for isolation of human olfactory epithelial tissue is important for clinical practice, because they provide cells for autologous transplantation and rule out graft rejection immune reaction and the risk of transmission viral infection and transfer of genetic defects, which can be associated with allotransplantation. __________ Translated from Kletochnye Tekhnologii v Biologii i Medicine, No. 4, pp. 185–193, December, 2006     

诱导多潜能干细胞在再生医学中的应用

背景：传统的器官或者细胞移植存在严重的供体来源不足和免疫排斥问题以及伦理学障碍。诱导多潜能干细胞有着近乎胚胎干细胞的自我更新能力和分化潜能,而且还拥有与患者一致的遗传物质,避免了免疫排斥反应,其应用前景十分广阔。 目的：综述诱导多潜能干细胞在再生医学领域应用研究的现状。 方法：应用计算机检索PubMed数据库(http://www.ncbi.nlm.nih.gov/PubMed)相关文章,检索时间为1997/2010,检索词为“induced pluripotent stem cell,diabetes,Parkinson’s disease,cardiovascular”,并限定文章语言种类为English。初检得到文献322篇,最终入选30篇文章进行综述。 结果与结论：疾病特异的诱导多潜能干细胞来源于患者本身,拥有与患者一致的遗传物质,既降低了移植后的免疫排斥,也避免了伦理学的问题。因此个体特异的诱导多潜能干细胞在再生医学领域有潜在的应用前景。     

心脏干细胞的研究与进展

背景：大量研究证明,哺乳动物心脏中存在心脏自身干细胞,参与心脏的自我更新和内源性修复。 目的：就心脏干细胞的来源、分类、特征及心脏病治疗等方面进行综述。 方法：由第一作者应用计算机检索PubMed数据库2000-01/2010-12有关心脏干细胞的来源、分化、特征及其在心肌再生方面的文章,检索词为“Cardiac stem cell”,包括临床研究和基础研究,排除重复研究和Meta 分析,共保留32篇文献进行综述。 结果与结论：心脏干细胞是一类存在于心脏组织内能够自我更新及克隆增殖的干细胞,它能够分化为心肌细胞、内皮细胞,参与心脏损伤修复,改善心功能。现已能够通过体外分离培养扩增后移植入动物心脏内,为下一步在临床上应用于人体打下了基础。但成体心脏干细胞自身的稳态平衡和动态变化,及其向心脏功能细胞分化需经历哪些具体过程,有哪些影响因素及如何调控等还不太清楚,需要继续研究以进一步证实。     

Multipotent stem cells from umbilical cord: cord is richer than blood!

The identification of mesenchymal stem cell (MSC) sources that are easily obtainable is of utmost importance. Several studies have shown that MSCs could be isolated from umbilical cord (UC) units. However, the presence of MSCs in umbilical cord blood (UCB) is controversial. A possible explanation for the low efficiency of MSCs from UCB is the use of different culture conditions by independent studies. Here, we compared the efficiency in obtaining MSCs from unrelated paired UCB and UC samples harvested from the same donors. Samples were processed simultaneously, under the same culture conditions. Although MSCs from blood were obtained from only 1 of the 10 samples, we were able to isolate large amounts of multipotent MSCs from all UC samples, which were able to originate different cell lineages. Since the routine procedure in UC banks has been to store the blood and discard other tissues, such as the cord and/or placenta, we believe our results are of immediate clinical value. Furthermore, the possibility of originating different cell lines from the UC of neonates born with genetic defects may provide new cellular research models for understanding human malformations and genetic disorders, as well as the possibility of testing the effects of different therapeutic drugs.     

The hopes of the mesenchymal stem cells in regenerative medicine]

The mesenchymal stem cells are a cell population of bone marrow, which have the capacity to differentiate towards all the cells from the locomotor apparatus. They also have immunomodulatory properties and can contribute to tissue repair, thanks to the secretion of many growth factors. Such cells are also found in the cord blood. In the same way, very close stem cells exist in great quantity in fat tissue. These cells are very good candidates in regenerative medicine. Besides, several clinical trials were carried out in order to highlight their effectiveness mainly in osseous repair and also during hematopoietic stem cells graft or cardiac repair after infarction. However, these trials will be able to develop fully only with the condition that culture techniques meeting the conditions of good manufacturing practice are set-up. This presentation gives a progress report on the whole of these subjects.     

牙髓干细胞在再生医学中的应用研究与进展

BACKGROUND:Dental pulp stem cells are characterized by multi-lineage differentiation and proliferation abilities and are easy to obtain, so they are becoming an issue of concern in regenerative medicine. OBJECTIVE:To provide clues and direction for further study by analyzing progress of domestic and overseas research on dental pulp stem cells, and summarizing their application in regenerative medicine. METHODS:The “dental pulp stem cell, regenerative medicine, tissue engineering” in Chinese and English served as the search terms to search articles related to dental pulp stem cells and regenerative medicine, published from 2000 to 2015 in Medline, PubMed, CNKI, Wanfang and Cqvip databases. Totally 46 articles were selected for overview.  RESULTS AND CONCLUSION:Dental pulp stem cells, which hold the capacity of self-renewal and multi-lineage differentiation, are relatively easy to obtain, and exhibit a great potential in regenerative medicine. The research of dental pulp stem cells in repairing bone defects has entered the clinical trial phase, but the research of cell differentiation into other tissues is still in basic trial phase and needs further development.     

Multipotent mesenchymal stromal cells in otorhinolaryngology

Multipotent mesenchymal stromal cells (MSCs) are primitive cells capable of restoring damaged mesenchyme and with the ability to differentiate into mature cells of bone, cartilage, muscle, fat, nerve or fibrous tissues. MSCs are therefore good candidates for applications in regenerative medicine and cell based therapy. They regenerate through self-renewal, differentiational capacity, immune modulation and secretion of bioactive molecules. Authors present a review of MSCs applications in otorhinolaryngology. The major interest is focused on phonosurgery, sensorineural deafness and reconstruction of large tissue defects with bone, cartilage or soft tissue replacement. Current evidence of MSCs treatment efficacy in otorhinolaryngology is based on animal models. The true impact on clinical treatment will not be known until clinical studies prove functional outcomes in human medicine.     

Primitive cardiac cells from human embryonic stem cells

Pluripotent stem cell-derived cardiomyocytes are currently being investigated for in vitro human heart models and as potential therapeutics for heart failure. In this study, we have developed a differentiation protocol that minimizes the need for specific human embryonic stem cell (hESC) line optimization. We first reduced the heterogeneity that exists within the starting population of bulk cultured hESCs by using cells adapted to single-cell passaging in a 2-dimensional (2D) culture format. Compared with bulk cultures, single-cell cultures comprised larger fractions of TG30(hi)/OCT4(hi) cells, corresponding to an increased expression of pluripotency markers OCT4 and NANOG, and reduced expression of early lineage-specific markers. A 2D temporal differentiation protocol was then developed, aimed at reducing the inherent heterogeneity and variability of embryoid body-based protocols, with induction of primitive streak cells using bone morphogenetic protein 4 and activin A, followed by cardiogenesis via inhibition of Wnt signaling using the small molecules IWP-4 or IWR-1. IWP-4 treatment resulted in a large percentage of cells expressing low amounts of cardiac myosin heavy chain and expression of early cardiac progenitor markers ISL1 and NKX2-5, thus indicating the production of large numbers of immature cardiomyocytes (~65,000/cm(2) or ~1.5 per input hESC). This protocol was shown to be effective in HES3, H9, and, to a lesser, extent, MEL1 hESC lines. In addition, we observed that IWR-1 induced predominantly atrial myosin light chain (MLC2a) expression, whereas IWP-4 induced expression of both atrial (MLC2a) and ventricular (MLC2v) forms. The intrinsic flexibility and scalability of this 2D protocol mean that the output population of primitive cardiomyocytes will be particularly accessible and useful for the investigation of molecular mechanisms driving terminal cardiomyocyte differentiation, and potentially for the future treatment of heart failure.     

Multipotent adult progenitor cell and stem cell plasticity

Stem cells are defined by their biological function. A stem cell is an undifferentiated cell that self-renews to maintain the stem cell pool and at the single-cell level differentiates into more than one mature, functional cell. In addition, when transplanted, a stem cell should be capable of replacing a damaged organ or tissue for the lifetime of the recipient. Some would argue that stem cells should also be capable of functionally integrating into nondamaged tissues. Stem cells are critical to both embryogenesis and postnatal life.     

流动优化骨髓间充质干细胞的分化状况

背景：间充质干细胞在成体动物骨髓中含量极低。 目的：观察成年大鼠骨髓间充质干细胞经生理范围流动切应力作用后,其体外生长规律、增殖及定向分化为成骨细胞及脂肪细胞的能力。 方法：在体外取得SD大鼠骨髓原代间充质干细胞,利用平板流室系统加载1 Pa切应力,对其进行培养及扩增,并分别向成骨细胞及脂肪细胞定向诱导。 结果与结论：原代间充质干细胞为长梭形或多角形,集落样生长;经流动加载并传代后细胞生长速度加快,不以集落方式生长,而是均匀分布。细胞体积明显增大,多数为长梭形或多角形;生长曲线显示各代细胞有类似的生长规律;激光共聚焦显微镜显示CD44和CD90阳性,CD31及CD45阴性;向成骨细胞及脂肪细胞诱导14 d后,Von Kossa染色及油红O染色均为阳性,流动优化后骨髓间充质干细胞保持了体外大量增殖及多向分化潜能。