Inhibition of plasma kallikrein. Kininase and kinin-like activities of preparations from the medicinal leeches

European Medicinal Leeches-New Roles in Modern Medicine

Before the advent of modern medicine, natural resources were widely used by indigenous populations for the prevention and treatment of diseases. The associated knowledge, collectively described as folk medicine or traditional medicine, was largely based on trial-and-error testing of plant extracts (herbal remedies) and the use of invertebrates, particularly medicinal maggots of the blowfly Lucilia sericata and blood-sucking leeches. The widespread use of traditional medicine in the West declined as scientific advances allowed reproducible testing under controlled conditions and gave rise to the modern fields of biomedical research and pharmacology. However, many drugs are still derived from natural resources, and interest in traditional medicine has been renewed by the ability of researchers to investigate the medical potential of diverse species by high-throughput screening. Likewise, researchers are starting to look again at the benefits of maggot and leech therapy, based on the hypothesis that the use of such animals in traditional medicine is likely to reflect the presence of specific bioactive molecules that can be developed as drug leads. In this review, we consider the modern medical benefits of European medicinal leeches based on the systematic screening of their salivary proteins.

Be ready at any time: postprandial synthesis of salivary proteins in salivary gland cells of the haematophagous leech Hirudo verbana

Sanguivorous leeches are ectoparasites having access to body fluids of potential hosts only infrequently. During feeding, salivary proteins are released from unicellular salivary glands into the wound. These substances, among them anti-coagulants, anti-inflammatory or anti-microbial agents, allow these animals proper feeding and long-term storage of host blood in their crops for several months. Using histological, protein biochemical and molecular techniques, we investigated whether synthesis of salivary proteins and refilling of salivary gland cells occur immediately after feeding or later when stored nutrients in the crop are getting scarce. The results of the histological analyses showed that gland cell area was significantly smaller right after feeding when compared with those in unfed animals. This parameter recovered quickly and reached the control level at 1 week after feeding. 2D gel electrophoresis and analysis of the abundance of individual proteins in extracts of leech tissues revealed that a subset of proteins that had been present in extracts of unfed animals virtually disappeared during feeding, but re-appeared within 1 week of feeding (most probably secretory proteins) while another subset did not change during the experimental period (most probably housekeeping proteins). Semi-quantitative PCR analysis of hirudin cDNA prepared from leech RNA samples revealed that the amount of hirudin transcripts increased immediately after feeding, peaked at 5 days after feeding and declined to control values thereafter. Our results indicate that bloodsucking leeches synthesize salivary proteins and refill their salivary gland cell reservoirs within a week of a blood meal to be prepared for another feeding opportunity.

Piyavit from the Medicinal Leech Is a New Orally Active Anticoagulating and Antithrombotic Drug

Piyavit, a novel pharmacological preparation allowed in Russia as an oral antithrombotic drug for clinical use, contains medicinal leech saliva as the main source of biologically active substances that inhibit platelet-vascular and plasmic hemostasis and provide thrombolysis. It is shown that piyavit administered orally or subcutaneously to animals inhibits arterial thrombus formation. In 22 patients with acquired heart valvular disease after implantation of a cardiac artificial valve who received oral piyavit capsules and phenilin 2-3 days after the operation, blood hypercoagulability was reduced in comparison to that of 20 patients after the same type of operation who received only phenilin. An antiinflammatory effect and decreased blood hypercoagulability were observed in 38 patients with thrombophlebitis of the greater saphenous vein who received the same piyavit capsules orally. The results confirm that piyavit as an oral anticoagulant and antithrombotic drug may be an alternative to known antithrombotic preparations. Key Words: Anticoagulation—Antithrombotic drug—Leech saliva— Medicinal leech-Piyavit.

Recommendations for the use of leeches in reconstructive plastic surgery

A written informed consent should be obtained from the patient before hirudotherapy is initiated. The patients should be treated each day of leech therapy with anti-Aeromonas antibiotics. Leeches should be applied on the darker spots of the reattached body parts or flaps. Usually 1-10 leeches are used for each treatment, while at the beginning, the patient might need two or more treatments per day. Leech therapy is used until venous capillary return is established across the wound border by angiogenesis. Usually the treatment with leeches lasts for 2-6 days. Hematologic evaluations should be performed every 4 hrs and the patient has to receive blood transfusions when the hemoglobin level is lower than 8 g/dL. Signs of regional lymphadenitis, slight swelling, and pain of regional lymph nodes on the side of leech application and subfebrile temperature can occur. Contraindications related to hirudotherapy include arterial insufficiency, hemophilia, hemorrhagic diathesis, hematological malignancies, anemia, hypotension, and sepsis. Leech therapy is not recommended in pregnancy and lactation and in patients with an unstable medical status, history of allergy to leeches or severe allergic diathesis, and disposition to keloid scar formation, as well as in those using anticoagulants and immunosuppressants.

Leech therapy for symptomatic relief of cancer pain

OBJECTIVE

Most patients with advanced stage cancer report moderate to severe pain. The leech (Hirudo medicinalis) is commonly used in traditional medicine for relief of localized pain.

DESIGN

We report a case of severe pain related to advanced stage cancer successfully treated by self-applied leeches.

SETTING AND PATIENTS

A 62-year-old male patient with synchronous renal cell carcinoma and leiomyosarcoma was admitted with severe pain in the lumbar region. The pain was refractory to radiotherapy, and systemic and epidural analgesic infusion.

RESULTS

Two months the patient came to the clinic in good condition free of pain. The patient reported outpatient self-treatment with seven leeches to the lumbar region in the interim that resulted in complete healing of pain.

CONCLUSIONS

This is the first report indicating possible activity of leeches in cancer pain.

The role of the leech in medical therapeutics

Leeching is considered by many to be a discredited medical relic of the past. This view is not justified, since leeches still play an important part in modern medicine, as in microsurgery and in the treatment of patients with post-phlebitic syndrome. Hirudin, the potent thrombin inhibitor of leech saliva, has been cloned and is used in the treatment of cardiological and hematological disorders. In our search for other antihemostatic factors in Hirudo medicinalis saliva, we found inhibitors of platelet aggregation induced by thrombin, collagen, adenosine 5'-diphosphate, epinephrine, platelet-activating factor and arachidonic acid. We purified apyrase (adenosine 5'-triphosphate diphosphohydrolase), which is a non-specific inhibitor of platelet aggregation by virtue of its action on adenosine 5'-diphosphate. We isolated and characterized the platelet-activating factor antagonist and also identified and recovered an inhibitor of coagulation factor Xa from leech saliva. This report summarizes our findings and those of other investigators, as well as the experience of one of us (A.E.) in leech therapy.

Arterial antithrombotic effect of piyavit, the novel pharmacological preparation from the medicinal leech, and of its components, prostanoids and enzyme destabilase

Piyavit, the novel pharmacological preparation from the medicinal leech (Hirudo medicinalis) contained the leech saliva, produces the potent arterial antithrombotic effect examined on experimental of Laser Induced Thrombus formation. Administrated orally into rats or injected subcutaneously as water extract, non-diluted or in 1600 times diluted, it inhibits statistically significant comparing with control platelet thrombus stimulated by laser beams. Its components, prostanoid fraction and purified enzyme destabilase, endo-epsilon-(gamma-Glu)-Lys-isopeptidase, also inhibit thrombus formation in statistically different manner, comparing with control. All the tested preparations inhibit platelet aggregation induced by ADP. The dependence of arterial antithrombotic effect on the leech prostanoid is discussed.