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 renewed1," he said.

The process of renewing these ceils 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 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 dying2," he said. from www.yingyukaoshi.com

With this finding, scientists are "opening the door to potential therapies to having ourselves3," heal ourselves Bhardwaj said. "Maybe one could devise a pharmaceutical agent that would make heart cells make new and more cells to overcome the problem they are facing."

But barriers remain. According to Bhardwaj, scientists do not yet know how to increase heart cell production to a rate that would replace cells faster than they are dying off, especially in older patients with heart failure. In addition, the number of new cells the heart produces was estimated using healthy hearts--whether the rate of cell turnover in diseased hearts is the same remains unknown.

詞匯

Longstanding adj. 為時甚久的turnover n. 更替率

Cardiac adj. 心臟的pharmaceutical n. 藥物

cardiomyocyte n. 心肌細胞therapy n. 療法、治療

注釋

1. It has previously not been known whether we were limited to the cardiomyocytes we are born with or if they could be renewed: 早前并不清楚人們是否局限于出生時所具有的細胞還是說這些細胞可以被更新。

2. Chronic heart failure arises from heart cells dying: 慢性心衰是由心肌細胞死亡導致的。

3. With this finding, scientists are "opening the door to potential therapies to having ourselves heal ourselves": 有了這一發(fā)現，科學家們正在打開讓我們自愈的潛在療法的'大門。

練習：

1. The human heart stops producing cardiac cells

A when a person is born. B when a person becomes old.

C when a person gets sick. D when a person dies.

2. The finding could prove to be helpful to

A the study of longstanding mysteries. B the analysis of cardiac cells.

C the prevention of chronic diseases. D the treatment of heart disease.

3. The people who're in their mid-70s, only 0.45 percent of cardiomyocytes

A are still functional B are replaced each year.

C are lost each year. D are damaged each year.

4. Chronic heart failure is associated with

A the death of heart cells. B the life span of a person.

C the effects of pharmaceuticals. D the weight of the patient.

5. It remains unknown whether the rate of cell turnover in diseased hearts

A changes over time. B can be monitored.

C is the same as that in healthy hearts.

D is high enough to replace cells faster than they're dying off.

答案與解析

1. D 短文的第一段說，科學家們發(fā)現，在人的整個生命過程中，其心臟不斷產生新的心肌細胞。言外之意，這個過程直到人死才會停止。

2. D 短文的第二段說，這一發(fā)現將為心臟病的治療開辟新的途徑。

3. B 短文的第四段說，一個人20 歲時，其每年被更替的心肌細胞為1%，隨著年齡的增長，該更替率不斷下降，等到75 歲時，只有0.45%。

4. A 短文的倒數第三段說，慢性心衰是由心肌細胞死亡導致的。

5. C 短文的最后一段說，心臟產生的新細胞的數量是按著健康心臟計算的，而有病心臟的細胞更替率是否與健康心臟相同還不得而知。