极小胚胎样干细胞分离技术的探讨 及临床应用前景

Very small embryonic⁃like stem cells (VSEL) are a type of non-hematopoietic stem cells. Their morphology and cell markers are similar to those of embryonic stem cells. They possess the multi-differentiation potential characteristics of embryonic stem cells and can differentiate into cells of the three germ layers including myocardial and vascular endothelial cells, without immune rejection, and can improve cardiac function and cardiac remodeling after acute myocardial infarction. The phenotype of VSEL cells is Sca⁃1+lin - CD45-, expressing markers of primitive pluripotent stem cells. They have a diameter of only 2 - 4 μm, larger than platelets and smaller than red blood cells, with a large nucleus containing euchromatin. Their quantity is extremely small, accounting for about 0.01% - 0.02% of the total mononuclear cells. They can be induced to differentiate into cardiomyocytes, neurons, etc. in vitro, and have very broad application prospects in tissue engineering and clinical treatment. However, bone marrow cells and umbilical cord blood cells have many types and complex components. Therefore, for wide clinical application, there must be a mature separation method to obtain a relatively high purity and a considerable quantity of very small embryonic⁃like stem cells. For this new favorite in the field of stem cells - very small embryonic⁃like stem cells, researchers have proposed multiple schemes for separating VESL from bone marrow or umbilical cord blood, but there is currently no uniformly recognized standard method. Currently, there are mainly 2 methods for the separation of VESL: immunomagnetic bead separation method and flow cytometry separation method. However, different methods have their own advantages and disadvantages and should be used in combination to make use of their strengths and avoid their weaknesses, for optimized combined sorting. First, use the immunomagnetic bead separation method for screening, and then perform flow cytometry separation.

极小胚胎样干细胞（very small embryonic⁃like stem cells，VSEL）是一种非造血干细胞，其形态学和细胞标志与胚胎干细胞有相似之处，具有胚胎干细胞多分化潜能特性，可以向包括心肌和血管内皮细胞在内的三个胚层的细胞分化，且无免疫排异，并能改善急性心肌梗死后的心功能和心脏重构。VSEL细胞表型为Sca⁃1+lin-CD45-，表达原始多能干细胞标志，直径仅为2~4 μm，较血小板大，比红细胞小，细胞核大，含常染色质。它们的数量极少，约占总的单个核细胞.的0.01%~0.02%，在体外可以被诱导分化成心肌细胞、神经细胞等，应用到组织工程和临床治疗前景十分广阔。然而骨髓细胞、脐带血细胞的组成种类多，成分复杂，所以要在临床上广泛应用必须有成熟的分离方法，以获得纯度较高且数量可观的极小胚胎样干细胞。对于干细胞领域的这一新宠—极小胚胎样干细胞，研究人员提出了多种从骨髓或脐带血中分离VESL的方案，但目前还没有统一公认的标准方法。目前主要有2种方法用于VESL的分离：免疫磁珠分离法、流式细胞分离法，但不同方法各有利弊，应联合应用扬长避短，进行优化联合分选，先应用免疫磁珠分离法筛选，再进行流式细胞分离。