WASHINGTON - Biologists have puzzled over why the heart begins beating so early in the foetus, before the tissues actually need blood infusion.

Two groups of researchers from Children’s Hospital Boston, Brigham and Women’s Hospital, and Harvard Stem Cell Institute (HSCI), presenting multiple lines of evidence from zebrafish, mice and mouse embryonic stem cells, provide an intriguing answer.

A beating heart and blood flow are necessary for development of the blood system, which relies on mechanical stresses to cue its formation.

Their studies offer clues that may help in treating blood diseases such as leukaemia, immune deficiency and sickle cell anaemia, suggesting new ways scientists can make the types of blood cells a patient needs.

This would help patients who require marrow or cord blood transplants, who do not have a perfect donor match, said a Children’s Hospital release.

These findings were published online by Cell and Nature Wednesday.