Haemophilia A is a rare genetic condition in which the blood does not clot properly.

Local scientists are studying the use of cord-lining stem cells to transport a specific gene into the body that will then go on to produce a clotting protein known as factor VIII, which patients lack.

In animal studies led by Professor Kon Oi Lian of the National Cancer Centre Singapore, stem cells carrying factor VIII were introduced into mice with the condition. Scientists found that the animals began to producethe protein.

The mice to which the gene was introduced also bled less when their tails were clipped.

"We were able to show, at least in a small animal model, that these cord-lining epithelial cells not only secreted factor VIII, but were able to mitigate, though not cure, the haemophilic mice," said Prof Kon.

Adeno-associated viruses (AAVs), which are not known to cause disease in humans, are now the commonly used vector for transporting the gene, but there have been some challenges.

One problem is that people infected before by the virus already produce neutralising antibodies against it, which means they would not be able to receive the gene.

"The AAV also does not insert itself into the genome, so it is possible the effect will wear off after a while," added Prof Kon, who is also with the Yong Loo Lin School of Medicine. Other viral vectors studied that insert themselves into the patient's genome have had adverse side-effects.

Prof Kon noted that cord-lining stem cells could provide an alternative method. Her team started studies on dogs last year.

Samantha Boh