Fibrinspecific liposomes as a potential method of delivery of the thrombolytic preparation streptokinase.

The use of streptokinase (SK) in the clinic is limited by the lack of fibrin-specificity and the short half-life of the drug. We have developed a new dosage form of streptokinase (immunoliposome), which consists of "free" native streptokinase and "bound" encapsulated in liposomes conjugated through carboxylated dextran with fibrin-specific monoclonal antibodies FnI-3C (IgG2 class), in a ratio of 60 and 40%, respectively, and studied their physicochemical properties, pharmacokinetic parameters, and the ability of fibrin-specific liposomes with SK for targeted delivery to fibrin in an in vivo experiment. The obtained immunoliposomes had a hydrodynamic diameter of ~ 140 nm, a zeta potential of - 19.6 mV, and entrapment efficiency of 14.1%. Fluorescent labels bound to immunoliposomes with streptokinase selectively accumulated in model rat vein thrombi at sites containing fibrin in 30 min after injection. Studies of pharmacokinetic parameters showed that the administration of immunoliposomes with streptokinase to rats was accompanied by an increase in the half-life from 1.8 to 24.1 min, the time to reach the maximum concentration from 15 to 30 min, and a decrease in the elimination constant by about 13 times compared with the native streptokinase preparation. Further studies are needed to evaluate the thrombolytic efficacy a new dosage form of streptokinase in experiment in vivo.

[CHARACTERISTIC OF APOPTOSIS OF CORONARY ARTERY CELLS WITH ATHEROSCLEROTIC LESIONS].

Aim: To study apoptosis of endothelial cells (EC), macrophages (MF) and smooth muscle cells (SMC) in the early atherosclerotic process (prior to plaque formation), elucidate mechanisms of its realization and evaluate effect on progression of atherosclerosis. Materials and methods: Histopathological studies were performed on coronary arteries affected by atherosclerosis taken at autopsy of patients with coronary heart disease (n = 63). To detect apoptosis, the TUNEL method was used for calculating the apoptotic index (AI) in paraffin sections. Phenotyping the cells and test for expression of active caspase 3 (AC-3) and apoptosis-inducing factor (AIF) were performed using sections of coronary arteries stained by immunohistochemistry. Results: The study of apoptosis showed a significant (p <0.0001) increase in AI of SMC, EC, MF coronary arteries affected by atherosclerosis compared with unaffected vessels. Progression of the atherosclerotic process led to a decrease of AI of SMC and EC. Statistical analysis revealed moderate feedback between AI of SMC and neointimal thickness in the development of atherosclerotic lesions (r = -0,44, p <0.0001). The amount of the AC-positive SMC and EC at the stage of lipoidosis significantly (p <0.0001) exceeded the number of AC -positive SMC at the liposclerosis stage. Expression of AIF was observed in the nuclei of EC in the newly formed vessels of hyperplastic intima. Conclusions: Early atherosclerotic lesions of the coronary arteries are accompanied by intense apoptosis of SMC, EC and MF. The intensity of apoptosis of SMC and EC decreases with the development of atherosclerosis. Progression of intimal hyperplasia at the early stages of atherosclerosis is associated with reduced apoptosis of smooth muscle cells and enhanced macrophage apoptosis. Apoptosis of SMC and MF is caspase-dependent. Apoptosis of endothelial cells can occur both with the participation of caspases and independently of them (with AIF).