《Nature》：心肌细胞可以再生

　　心肌细胞生长的进一步研究

　　干细胞技术可被用于受损心脏治疗

　　2008-4-23——科学家们成功的在试管中培养了"master"心脏细胞，应用于心功能受损的小鼠后，可明显改善其心脏功能。这项发现被称为是心血管再生药物探索之路上的又一重要的里程碑。

　　全球的研究者们都在致力于诱导干细胞向各种心脏细胞分化，以用来修复或替换受损的心脏组织。干细胞是细胞最先的祖始，有向各种细胞分化的能力。越来越多的医学证据表明，胚胎干细胞最终可为移植提供有功能的心脏组织。由纽约Mount Sina 医学院基因细胞学研究所的Gordon Keller带领的一个由美国、加拿大、英国科学家们组成研究组，近日报道称，他们在实验室成功地从胚胎干细胞培养出了三种人心脏细胞。

　　人的心脏是由心肌细胞、内皮细胞和血管平滑肌细胞三种不同的细胞组成的。每种细胞在构成心脏功能中都起到了重要的作用。Keller的研究组培养了一种master心脏细胞，这种细胞是在实验的几个关键时点向干细胞的培养皿中加入几种生长因子和生长相关分子后培养出来的。在准确同步化以上步骤后，研究者成功将干细胞培养成三种心脏特定细胞的祖细胞。

　　将这三种体外培养的心脏细胞一起移植到心脏病小鼠模型体内，小鼠的心脏功能得到明显改善。他们的研究为用干细胞生物技术治疗人类受损心脏提供了新的希望。Keller和他的同事们认为每种心脏细胞可单独由各自的祖细胞生成，这为进一步明确心脏发育提供了新的证据。他们将研究发表在Nature四月第23期杂志上。

New Steps Toward Growing Heart Cells

Research Could Lead to Stem Cell Techniques for Treating Damaged Hearts

April 23, 2008 -- Scientists have successfully grown "master" heart cells in a test tube and used them to significantly improve ailing heart function in mice. It’s an achievement that’s being lauded as another promising milestone in the quest toward cardiovascular regenerative medicine.

Researchers across the globe have been trying to coax stem cells into viable heart cells that can be used to repair or replace damaged cardiac tissue. Stem cells are the earliest precursors to cells; they have the potential to develop into a variety of different kinds of cells. A growing body of medical evidence suggests that embryonic stem cells may ultimately allow for the creation of functional heart tissue for transplants.

 Now a team of U.S., Canadian, and British researchers led by Gordon Keller of the department of gene and cell medicine at Mount Sinai School of Medicine in New York reports success in growing three types of human heart cells from laboratory cultures derived from embryonic stem cells.

The human heart comprises three distinct cell types: cardiomyocytes, endothelial cells, and vascular smooth muscle cells. Each type of cell plays an important part in the makeup of functioning heart tissues.

Keller’s group created the so-called master heart cells by adding a mix of growth factors and other development-related molecules to the laboratory dishes containing the stem cells at key times during the experiment. By timing these steps correctly, the researchers encouraged the cells to grow into ancestors, or "progenitors," of the three specific heart cell types.

When the team transplanted a combination of the three lab-grown heart cells into mice with simulated heart disease, their heart function improved. Researchers say their success offers hope to those aiming to develop stem cell biology techniques for the treatment of damaged human hearts.

Keller and colleagues believe that individual types of specific heart cells could be produced by isolating particular types of progenitors, an accomplishment that will help promote further understanding of heart development.

The researchers published their findings in the April 23 issue of Nature.

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