An implantable device has been developed by US researchers for patients with haemophilia. It is reported to convert inactive clotting factors to active ones in vivo.
Haemophilia is caused by a deficiency of factor VIII or IX and is treated by the administration of these factors. Dr Tung Ton-That (department of anatomy and cell biology, Uniformed Services University school of medicine, Bethesda) and colleagues developed the device which is a porous chamber that contains immobilised factor Xa or XIIa. These factors convert factor VII to active VIIa which then diffuses out of the chamber into the blood, where it can bypass the deficient factors. The researchers implanted the peritoneal device in rhesus monkeys where it was shown to work for a month (Nature Biotechnology 2000;18:289).