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【Nature News—编译】“心脏更新”细胞被发现NA
“心脏更新”细胞被发现
Roxanne Khamsi
再生型细胞为心脏病幸存者带来希望
心脏所包含的细胞在生后也会分化并成熟，这使得心脏自身能够再生。这一令人惊奇的发现使得在心脏病发作后通过移植这些细胞来修复受损的心脏成为可能。
心脏病发作会杀死许多心脏内的许多细胞。这些细胞死亡后被疤痕组织所取代，这一组织是由结缔组织细胞——纤维母细胞所形成的。这一过程所造成的后果是心脏的某些部位变薄并使其不能正常地舒缩。
由于完全分化的心肌细胞不能再分化，医学专家便认为心脏在损伤后不能进行更新。但是加利福尼亚大学圣地亚哥分校Kenneth Chien与他合作者的研究结果现在改变了这一观点。
研究人员们在发育早期的心脏内寻找“心脏祖细胞”，这种细胞仍保留着再生的能力。他们寻找的细胞包含islet-1基因的表达产物，这些产物在心肌祖细胞上表达。
通过对发育中小鼠细胞的示踪，Chien和他的合作者们将成熟细胞中表达islet-1产物的部分与大量的胚胎细胞联系起来，它们都能行生心肌。在人的心脏中他们也发现了这种类型的细胞。
“这些细胞非常稀少，这就是为什么到现在还没有人报道的原因”Chien解释说，“在出生以后仅仅有数百个祖细胞存在，并且这个数量随着年龄的增长会逐渐减少。”
在实验室中，从新生的动物心脏中取出的几百个祖细胞产生了数百万个心肌细胞。这种祖细胞主要在心脏的腔内存在，他们在Nature1上报这一研究结果。
和干细胞不同，干细胞看起来具有一种不受限制的自我更新能力，祖细胞的分裂的次数是有限的。但是这两种类型的细胞都具有用于修复受损心脏的能力。
研究人员认为，心脏祖细胞比干细胞有一个巨大的优点：科学家能够很容易的将祖细胞完全特化为心肌细胞，而不需要利用化学或激素的刺激。
将来，医生能够获得并培养心肌祖细胞在激将它们种植到患者的心脏中。然而获取相当数量的这些细胞在技术上仍然存在重大的挑战。“将这些细胞用于治疗还需要很长的时间”Chien说。
References
1. Laugwitz K. L., et al. Nature 433, 647 - 653 (2005). | Article | PubMed |
原文：
http://www.nature.com/news/2005/050207/full/050207-8.html
Published online: 9 February 2005; | doi:10.1038/news050207-8
'Heart-renewing' cells discovered
Roxanne Khamsi
Regenerating cell type promises much for heart-attack survivors.
The heart contains cells that can divide and mature after birth, which might allow the organ to regenerate itself. This surprise discovery raises the possibility of transplanting these cells into hearts crippled by heart attack to mend the damage.
A heart attack kills off many cells in the heart. These are replaced by scar tissue, made up of connective-tissue cells, called fibroblasts. As a result, parts of the heart become thin and fail to beat properly.
Because fully developed heart cells do not divide, medical experts viewed the organ as unable to regenerate after injury. But Kenneth Chien, of the University of California, San Diego, and his colleagues now challenge this belief.
The researchers searched for 'cardiac progenitor cells', which are rare cells from the heart's early development that retain the ability to reproduce. They looked for cells containing the products of a gene called islet-1, which is expressed in these progenitor cells.
By tracking cells in developing mice, Chien and his team linked adult cells expressing islet-1 with a population of embryonic cells that can give rise to heart muscle. The group also discovered these cell types in the human heart.
"These are very rare cells, which accounts for why they have not yet been reported," explains Chien. Only a few hundred progenitor cells remain in the heart after birth, and this number decreases with age, the researchers say.
In the lab, several hundred progenitor cells taken from animals after birth produced millions of cardiac-muscle cells. The progenitor cells are found mainly in the heart's pumping chambers, the team reports in Nature1.
Unlike stem cells, which have a seemingly unlimited capacity for self-renewal, progenitor cells undergo a finite number of divisions. But both types of cells have potential for use in repairing heart damage.
And according to the researchers, cardiac progenitor cells have one considerable advantage over stem cells: scientists can easily coax them into becoming fully specialized heart-muscle cells, without chemical or hormonal stimuli.
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作者:admin@医学,生命科学 2011-06-06 21:43
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