Nature聚焦北京再生医学会议 几项干细胞成果瞩目

　　

生物通报道，2009年5月15日，中国医学科学院和美国纽约科学院共同主办的“北京2009再生医学国际会议”近期在北京协和医学院召开，卫生部部长陈竺出席开幕式并致词。会议对当前国际再生医学领域取得的最新突破以及未来的发展方向和策略进行了充分研讨交流。

诺贝尔生理学及医学奖获得者威塞尔博士（Torsten  Wiesel）等国内外再生医学界200多名专家和科研人员就生理学、干细胞生物学、器官发生学、移植与耐受等内容进行交流。

 

其中干细胞和iPS技术引人瞩目。今日Nature发布新闻聚焦大会干细胞新成果。

 

来自麻省总医院的干细胞专家Ibrahim Domian和哈佛大学医学院干细胞研究所的专家Kenneth Chien在大会上做报告，首次分离到小鼠胚胎中的心肌祖细胞，这类祖细胞具有分化成心肌细胞的潜能。这类干细胞可能成为研究心脏疾病的最佳模型，也对寻找人类心肌祖细胞具有指导意义。

 

Chien在标记转基因小鼠的心肌祖细胞，通过这些标记找出分化成特定心肌细胞的祖细胞。通常，心肌祖细胞群可以分化成心肌细胞、平滑肌细胞和内皮细胞，但是具体哪类祖细胞是分化成哪类功能细胞的机制一直不清楚。Chien的研究首次分离获得分化成心肌细胞的祖细胞，这类细胞能特异表达Islet-1蛋白。

 

来自德国汉诺威医学院的干细胞专家Ulrich Martin在大会上报告了，用iPS技术诱导脐带血细胞的进展。经过程序重排的脐带血细胞经培养形成典型的胚胎体，这些胚胎体包含三个典型的胚层。其中，1/5的细胞包含有心肌细胞样的细胞。

 

Martin和他的研究团队将继续培养这些心肌样细胞，期望有天能将这些细胞用于心脏移植术中。

（生物通 小茜）

 

生物通推荐原文阅读：Early heart muscle cells identified

链接地址：http://www.nature.com/news/2009/090529/full/news.2009.522.html

Researchers may have isolated embryonic mouse cells that are committed to becoming cardiac myocytes, the type of heart muscle cells that are capable of coordinated contraction. Such cells could be a powerful tool in animal models of heart disease, and might pave the way for identifying the equivalent cells in humans.

 

"If the cells are what [the researchers] think they are, it will be a significant step forward," says Ulrich Martin, a stem-cell researcher at Hannover Medical School, Germany, who was not involved with the research. The results were presented this month at a meeting on regenerative medicine in Beijing.

 

Previously, scientists had identified so-called multipotent secondary-heart-field (SHF) progenitors — those that can give rise to different major cell types in the mature heart, such as cardiac myocytes, smooth muscle cells and endothelial cells that form the interior surface of blood vessels. However, little is known about what drives these progenitor cells down one path instead of another. And that's not good for regenerative medicine, as transplanting SHF progenitor cells into a heart might mean they end up turning into a cell type other than heart muscle.

 

Ibrahim Domian, of Massachusetts General Hospital in Boston, and Kenneth Chien, of the hospital and the Harvard Stem Cell Institute, have been working on ways to label populations of cardiac progenitor cells in transgenic mice. At the Beijing meeting, Domian reported that they had isolated embryonic stem cells from those mice and identified different progenitor populations that express different sets of genes. One type of progenitor expressed the protein Islet-1, a marker of SHF progenitors; in culture, the cells divided for a few days before differentiating into mature cardiac muscles.

 

The researchers also found that cardiac myocetes derived from these progenitor cells contracted with a level of force — the defining characteristic of cardiac muscle — that was the same as neonatal cardiac myocytes. Domian declined to discuss details, stating that the results are under review at a journal.

 

"This is a very interesting study," says Martin. Progenitor cells that are committed to becoming cardiac muscles, but that can still reproduce, would allow researchers to expand them in culture before transplantation.

 

Domian and his colleagues are now trying to see if there are equivalent cardiomyocyte progenitors in humans, but these are more difficult to study because there are limited samples. So researchers such as Martin have turned instead to induced pluripotent stem (iPS) cells, which are artificially derived from cells that usually differentiate into only one type, but are then forced to express certain 'reprogramming factors' that allow them to develop into all cell types.

 

In other work reported at the Beijing meeting, Martin and his colleagues introduced some of those reprogramming factors into human umbilical-cord blood cells and generated iPS cells that are very similar to embryonic stem cells. When cultured in suspension, those cells formed the typical aggregates called embryonic bodies that contain cells from all three germ layers, a definitive feature of embryonic stem cells. One-fifth of the embryonic bodies were contracting clusters, and contained cells that looked and behaved like cardiac myocytes.

 

Martin and his team are now promoting and enriching particular heart-cell lineages that could be used as cellular transplants for treating heart disease.