PIGS MAY may now rule the heart's of men. Dr David White, an immunologist and lecturer in clinical surgery at Cambridge University in UK, has discovered a way of transferring human genes to pigs, to breed hearts on demand.

A breakthrough has come in isolating and engineering the gene responsible for producing species-specific protein regulators, known as RCAs, to counter enzymes that destroy foreign tissue. These RCAs successfully counter complements of the same species and if a pig's heart is transplanted in a human, in normal circumstances the pig's RCA would be unable to counter the patient's complements.

White and John Wallwork, a surgeon at Papworth Hospital in UK, have already engineered a human RCA-producing mouse and intend to use the same technique by genetically altering a fertilised pig ovum and implanting it in a sow.

Once a transgenic piglet is produced, scientists hope to start a breeding colony which could produce human- compatible hearts.