In ancient medical books in China, it was recorded that leeches were used to treat a variety of diseases, and in the middle of>, it means "mainly expelling evil blood, blood stasis, closing the moon, breaking blood and resolving food stagnation ...". Zhang Zhongjing, a medical sage, used it to eliminate pathogenic factors and strengthen the body resistance, and treated the symptoms of "blood stasis" and "water depression", which showed its unique curative effect.

Zhang Xichun praised this medicine in the later generations: "Blood stasis does not hurt new blood, it is a good medicine, pure as water, but qi is not damaged at all, while blood stasis is invisible."

Before 1500, the Egyptians began bloodletting therapy with medical leeches. By the beginning of last century, Europeans were more superstitious that medical leeches could suck sick blood from human body, and they used medical leeches for blood-sucking treatment regardless of headache and brain fever. Later, with the development of medicine, this superstitious treatment method was gradually abandoned. However, in recent years, the new use of medical leeches in medicine has been widely concerned.

Plastic surgeons use medical leeches to eliminate congestion and reduce necrosis in the vascular occlusion area after operation, thus improving the success rate of tissue transplantation and breast formation. When medical leeches are replanted or transplanted to fingers, toes, ears and nose, using medical leeches to suck blood can make veins unobstructed and greatly improve the success rate of surgery.

This is because the salivary glands of medical leeches secrete anticoagulant hirudin and histamine-like substances that dilate blood vessels when sucking blood. 65438-0987 Leech Research Group of Institute of Aquatic Animals of China Academy of Sciences cooperated with Orthopedics Department of the Third Affiliated Hospital of Hubei Medical University. Medical leeches were first used in China to treat blood stasis after replantation of severed fingers, and several cases were successful, which was widely praised at home and abroad.

A variety of active substances contained in the saliva of medical leeches are attracting wide attention from scientists all over the world and have become a hot spot for the utilization of resource animals. From 65438 to 0984, Dr. Sawyer, an American leech expert, founded the world's first leech farm and biochemical drugs Company in Sethi, Wales, England. Hirudin and hyaluronidase produced by this company have been sold to European and American countries and Japan, and tens of thousands of live medical leeches have also been sold.

Recently, a medical leech farm was built in Charleston, USA. France and Germany have transferred the gene for synthesizing hirudin into yeast and Escherichia coli, and produced cheap hirudin through genetic engineering. It can be seen that the demand and output of hirudin are expanding.

Hirudin is a low molecular weight (7000) polypeptide composed of 65 amino acids, in which glutamine and asparagine have higher molecular weight and lower isoelectric point (3.8 ~ 4.0), and are stable for a long time at room temperature. Hirudin is the most effective natural anticoagulant known, superior to heparin, and has anticoagulant and thrombolytic effects, that is, the function of promoting blood circulation and removing blood stasis in traditional Chinese medicine. Therefore, it shows great advantages and broad prospects in the treatment of septic shock, atherosclerosis, cerebral infarction, cardiovascular diseases, hypertension, ophthalmology and many other diseases lacking antithrombin.