心脏和骨骼(Hearts and Bones)_生物论文

　　引言：看似毫不相关的两样东西，其实它们之间有着千丝万缕的联系，这就是生命的奥秘。

　　心脏病发作是非常危险的，对于那些幸存活着的人来说，这仅仅是困难的开头。幸存下来的心脏组织是很脆弱的，受过创伤的心脏几乎不能正常的工作。很多科学家都试图找到一种途径来修复心脏的损伤。现在，有两个研究小组报道：一群来自骨髓的细胞可以帮助受损的心脏恢复某些功能。

心脏的变化：来自骨髓的干细胞（左图）变成了心脏的肌肉细胞（右图）

　　纽约医学学院的Piero Anversa在Nature上详细的描述了他们是如何从成年的小鼠骨髓中得到多功能的干细胞。然后，他们在30只小鼠身上进行试验，诱导小鼠心脏发生心脏病状的损伤，然后把骨髓细胞注射到幸存的心脏组织中。骨髓细胞提前经过荧光处理，所以新生的细胞很容易被追踪。

　　注射骨髓细胞9天以后，在30只小鼠中有12只小鼠的移植的细胞就开始形成新的心脏组织――心肌细胞和一些血管。不仅受损的组织被新的组织取代，甚至心脏的功能也有所提高。

　　哥伦比亚大学的Silviu Itescu 同时也正在进行一项类似的研究工作。他和他的同事从一些支援者的骨髓中分离出一些骨髓细胞，这些细胞将来可以变成血液活着血管。他们把这些取自人体的细胞注射到小鼠的血管内。这些小鼠已经被诱导出心脏病。注射细胞后的2个星期，受损的心脏明显的开始吸引移植来的新细胞。由人体细胞建成的毛细血管占整个心脏毛细血管的20%－25%。四个月以后，注射过人骨髓细胞额小鼠，其心脏损伤组织的比例已经明显减少，心脏功能也明显好转。

　　美国克利夫兰市临床基金会的一名心脏学专家说：两组接受试验的小鼠，“康复的进程都显著提高了”，这两项研究都是非常成功的实验。但是他提醒那些灰心的心脏病专家：在心脏病研究领域中：在动物身上进行实验是非常诱人的实验模式。

原文：

Hearts and Bones

A heart attack is dangerous enough, but for patients whosurvive, it‘s only the beginning of a lot of trouble. Surviving heart tissue isweakened and a scarred heart can’t function properly. Many scientists haveattempted to discover a way to repair the damage. Now, two groups report thatcells derived from bone marrow can help restore some function to damaged hearttissue.

Change of heart. Stem cells from bone marrow (left) became heart muscle cells(right).
CREDIT: CDC

In astudy in the 5 April issue of Nature, released today, a team led byPiero Anversa of New York Medical College in Valhalla and Donald Orlic of theNational Human Genome Research Institute in Bethesda, Maryland, describes howthey harvested so-called multipotent stem cells from the bone marrow of adultmice. They then induced heart attack-like damage in 30 mice, and injected thebone marrow cells into surviving heart tissue. The donor mice carried the genefor green fluorescent protein, so the fate of the new cells was easy to follow.

Nine daysafter the injection, the transplanted cells were forming new hearttissue--muscle cells as well as blood vessels--in 12 of the 30 mice. Not onlywas the damaged tissue full of green cells, the mice also showed improved heartfunction compared to animals that had heart damage but received either no cellsor a different type of cell from the bone marrow.

A slightlydifferent tack was taken by Silviu Itescu of Columbia University in New YorkCity. He and his colleagues isolated cells from the bone marrow of humanvolunteers that were destined to become blood and blood vessels. They injectedthe human cells into the blood stream of rats in which the team had induced aheart attack. Signals from the damaged heart evidently attracted thetransplanted cells, the team reports in the April issue of Nature Medicine;2 weeks after the injection, capillaries made of human cells accounted for 20%to 25% of capillaries in the heart. Four months after the operation, rats thatreceived the blood vessel precursors had significantly less scar tissue--andbetter heart function--than control rats. Because the procedure is similar tothe bone marrow transplants doctors use to treat leukemia and other cancer,Itescu says, he and his colleagues might be ready to try the strategy in humansin a year.

Theresults intrigue cardiologist Eric Topol of the Cleveland Clinic Foundation."The healing was markedly improved" in both sets of treated animals,he says, and the studies were well-designed. But he cautions that cardiologistshave been disappointed before. The field has seen several "very attractivemodels that worked in animals that didn‘t pan out when they got to theclinic," he says.

--GRETCHENVOGEL