Single-drug approach with rivaroxaban: A case of successful anticoagulation against cancer-associated thrombosis

Purification and characterization of a novel thermostable anticoagulant protein from medicinal leech Whitmania pigra Whitman

ETHNOPHARMACOLOGICAL RELEVANCE

The prevalence of cardiovascular disease (CVD) is increasing worldwide. Despite significant improvements in novel targeted treatment agents, natural products purified from medicinal animals with minimal side effects have attracted much attention. Several native proteins explored from suck-blood leeches, such as non-thermostable hirudin and its variants, revealed potent anticoagulant activity. Traditional Chinese medicine clinics have proved that non-suck-blood leech Whitmania pigra Whitman (W. pigra) also played notable roles in CVD treatments even after decoction. However, only a few natural proteins and peptides have been identified from the fresh material of this medicinal species.

AIM OF THE STUDY

We aimed to purify and characterize thermostable anticoagulant proteins from W. pigra for further development of a therapeutic agent for thrombosis.

MATERIALS AND METHODS

W. pigra crude extract was prepared by decoction in water. Anticoagulant proteins were purified by DEAE cellulose DE-52, Sephadex G-75, and reversed-phase liquid chromatography sequentially and analyzed by SDS-PAGE and LC-MS/MS for structural information. In addition, we conducted in vitro anticoagulant experiments, including plasma recalcification time (PRT) assay, fibrinolytic assay, activated partial thromboplastin time (APTT), prothrombin time (PT), thrombin time (TT), fibrinogen (Fib) assay, and cell viability assays. Furthermore, a carrageenan-induced chronic thromboembolism model was employed in ICR mice, and four coagulation factors (APTT, PT, TT, and Fib) activities were determined after intragastric administration.

RESULTS

The anticoagulant protein WP-77 has a relative molecular weight of ca. 20.8 kDa. It was effective over a broad temperature range from 20 °C to 100 °C and a pH 2-8 condition. The anticoagulant activity of WP-77 was retained after incubation with pepsin but was greatly inhibited by trypsin (P < 0.01). It significantly prolonged APTT and TT (P < 0.05) but had little effect on PT and Fib in vitro. Furthermore, WP-77 of a low concentration resulted in the recovery of injured EA.hy926 by thrombin. The protein also significantly prolonged APTT and TT (P < 0.01) and inhibited thrombus formation in carrageenan-induced thrombosis mice, demonstrating its antithrombotic effect in vivo.

CONCLUSION

Our results suggest that WP-77 from W. pigra plays a distinct role in treating thrombotic diseases, and it is an essential substance of anticoagulant activity of non-suck-blood medicinal leeches. This thermostable anticoagulant protein could be a promising candidate for the development of clinical antithrombosis medicines.

Fracture of a Retrievable Inferior Vena Cava Filter Placed for Cancer-associated Thrombosis in a Patient with Malignant Lymphoma

Venous thromboembolism occurs in prothrombotic states, such as malignancy. To prevent fatal pulmonary thromboembolism, an indwelling inferior vena cava (IVC) filter is considered in addition to anticoagulation therapy. We herein report a case of fracture of a retrievable IVC filter in a malignant lymphoma patient. One of the filter arms was fractured and fixed to the IVC wall after one year. Since dislocation of the fractured arm was assessed correctly using three-dimensional computed tomography, we were able to retrieve the main body of the IVC filter successfully. Indications and management of IVC filter fracture should be discussed.