HONG KONG, June 5 (Reuters) - Scientists in Japan have identified a protein that appears to help develop a healthy heart, according to initial studies done on frogs.

In their findings, published in the journal Nature, they described how they zeroed in on the protein, IGFBP-4, and then removed it from tadpoles after their hearts were formed.

"After the molecule was knocked down (removed), their hearts became smaller and smaller and finally disappeared," Issei Komuro at the Chiba University Graduate School of Medicine in Japan said in a telephone interview.

"I hope we can use the molecule for cardiac regeneration after heart failure (in people)," he said.

The heart is the first organ to form in the earliest stages of the development of the human embryo and abnormalities in this process can result in congenital heart diseases, the most common cause of birth defects in humans.

Komuro said it was not clear if the protein plays any role in the differentiation of embryonic stem cells into heart cells, but he said the experiment suggested it was crucial in maintaining the development of a healthy heart.

"IGFBP-4 is secreted by the liver, promotes cardiac development and its expression is relatively late. First the heart is formed, then in the mid-stage of the embryo, the molecule is needed somehow to maintain the development of the heart," Komuro said.

"After the heart is formed, and when the molecule is knocked down (removed), the heart disappears. This we proved in the frog." (Reporting by Tan Ee Lyn; Editing by Sanjeev Miglani)

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