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

人體心臟可產(chǎn)生新細(xì)胞

科學(xué)家解開了一個(gè)為時(shí)甚久的謎團(tuán)，他們發(fā)現(xiàn)人類心臟在人的一生中不斷地產(chǎn)生新的心肌細(xì)胞，盡管新細(xì)胞產(chǎn)生的速度隨年齡增長(zhǎng)而放緩。

此番發(fā)現(xiàn)發(fā)表于今年4月3日出版的《科學(xué)》雜志，這一發(fā)現(xiàn)可能為心臟疾病的治療比如心臟衰竭、心臟病發(fā)作開辟出一條新途徑，專家稱。

“我們發(fā)現(xiàn)心臟中的搏動(dòng)細(xì)胞心肌細(xì)胞是可再生的”，首席研究員喬納斯·弗瑞森談到。他是一名在瑞典斯德哥爾摩的卡羅林斯卡學(xué)院從事干細(xì)胞研究的教授。“早前并不清楚人們是否局限于出生時(shí)所具有的心肌細(xì)胞還是說這些細(xì)胞可以被更新”，他說。

這些細(xì)胞的更新過程隨時(shí)間的推移而有所變化，弗瑞森補(bǔ)充道。一個(gè)人20歲時(shí)，其每年被更替的心肌細(xì)胞約為l%，隨著年齡的增長(zhǎng)，該更替率不斷下降，等到75歲時(shí)，只有0.45%。

“如果我們能明白新的心肌細(xì)胞的產(chǎn)生是如何控制的，我們就有可能開發(fā)出醫(yī)藥品來促進(jìn)這一過程的實(shí)現(xiàn)，可以刺激心肌細(xì)胞的再生，比如在心臟病發(fā)作以后”，弗瑞森說。

這樣的治療方案可以幫助恢復(fù)受損心臟。

“許多人遭受慢性心力衰竭的折磨”，同樣來自卡羅林斯卡學(xué)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細(xì)胞的死亡導(dǎo)致的”，他說。

有了這一發(fā)現(xiàn)，科學(xué)家們正在“打開讓我們自愈的潛在療法的大門”，布哈德瓦基說。“或許人們可以發(fā)明一種能使心肌細(xì)胞產(chǎn)生新的更多細(xì)胞的藥劑以克服他們正面臨的問題。”

話雖如此，困難尤存。根據(jù)布哈德瓦基的說法，科學(xué)家們還不知道如何使心臟細(xì)胞更新的速度快于細(xì)胞死亡的速度，尤其是對(duì)于那些心力衰竭的老年患者而言。此外，心臟產(chǎn)生新細(xì)胞的數(shù)量是按照健康心臟計(jì)算的，而有病心臟的細(xì)胞更替率是否與健康心臟相同還不得而知。

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