Leeches don't lose their touch in transplantations
The medicinal leech, Hirudo medicinalis – not a very popular animal – has revived its reputation in medicine during the last decade. It is, however, no longer used to bleed people and thereby restoring the balance of the body fluids, but to stimulate the circulation of the blood. If, for example, you are in an accident and your finger is torn off, there can be problems in getting the blood vessels to work normally after they have been sewn back together. That is when leeches are used.
When leeches suck blood and the blood comes into their mouths, it ought to coagulate which would prevent them from eating again. But the leech’s intestine produces the polypeptide hirudin, which in a specific way stops the blood clotting. This property is used to prevent the occurrence of thrombosis in plastic surgery. It aids the blood flowing in a finger that has been sewn back and thus prevents the tissues dying from lack of oxygen. Many different substances have been identified from the saliva of varying species of leeches. They all affect the ability of the blood to clot and attempts are being made to develop new drugs from them.
Heparin is another means of hindering the clotting of blood. It is extracted from the mucous membranes of the stomachs of pigs and cattle.