Human Heart Can Make New Cells

Solving a longstanding mystery,scientists have found that the human heart continues to generate new cardiac cells throughout the life span,although the rate of new cell production slows with age.

The finding,published in the April 3 issue of Science,could open a new path for the treatment of heart diseases such as heart failure and heart attack,experts say.

"We find that the beating cells in the heart,cardiomyocytes,are renewed,"said lead researcher Dr.Jonas Frisen,a professor of stem cell research at the Karolinska Institute in Stockholm,Sweden."It has previously not been known whether we were limited to the cardiomyocytes we are born with or if they could be renewed,"he said.

The process of renewing these cells changes over time,Frisen added.In a 20-year-old,about 1 percent of cardiomyocytes are exchanged each year,but the turnover rate decreases with age to only 0.45 percent by age 75.

"If we can understand how the generation of new cardiomyocytes is regulated,it may be potentially be possible to develop pharmaceuticals that promote this process to stimulate regeneration after,for example,a heart attack,"Frisen said.

That could lead to treatment that helps restore damaged hearts.

"A lot of people suffer from chronic heart failure,"noted co-author Dr.Ratan Bhardwaj,also from the Karolinska Institute."Chronic heart failure arises from heart cells dying,"he said.

With this finding,scientists are "opening the door to potential therapies to having ourselves heal ourselves,"Bhardwaj said."Maybe

人体心脏可产生新细胞

科学家解开了一个为时甚久的谜团，他们发现人类心脏在人的一生中不断地产生新的心肌细胞，尽管新细胞产生的速度随年龄增长而放缓。

此番发现发表于今年4月3日出版的《科学》杂志，这一发现可能为心脏疾病的治疗比如心脏衰竭、心脏病发作开辟出一条新途径，专家称。

“我们发现心脏中的搏动细胞心肌细胞是可再生的”，首席研究员乔纳斯·弗瑞森谈到。他是一名在瑞典斯德哥尔摩的卡罗林斯卡学院从事干细胞研究的教授。“早前并不清楚人们是否局限于出生时所具有的心肌细胞还是说这些细胞可以被更新”，他说。

这些细胞的更新过程随时间的推移而有所变化，弗瑞森补充道。一个人20岁时，其每年被更替的心肌细胞约为l%，随着年龄的增长，该更替率不断下降，等到75岁时，只有0.45%。

“如果我们能明白新的心肌细胞的产生是如何控制的，我们就有可能开发出医药品来促进这一过程的实现，可以刺激心肌细胞的再生，比如在心脏病发作以后”，弗瑞森说。

这样的治疗方案可以帮助恢复受损心脏。

“许多人遭受慢性心力衰竭的折磨”，同样来自卡罗林斯卡学院的文章合著者拉坦·布哈德瓦基指出。“慢性心力衰竭是由心肌细胞的死亡导致的”，他说。

有了这一发现，科学家们正在“打开让我们自愈的潜在疗法的大门”，布哈德瓦基说。“或许人们可以发明一种能使心肌细胞产生新的更多细胞的药剂以克服他们正面临的问题。”

话虽如此，困难尤存。根据布哈德瓦基的说法，科学家们还不知道如何使心脏细胞更新的速度快于细胞死亡的速度，尤其是对于那些心力衰竭的老年患者而言。此外，心脏产生新细胞的数量是按照健康心脏计算的，而有病心脏的细胞更替率是否与健康心脏相同还不得而知。

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