Thrombolytic potency of acid-stabilized plasmin: superiority over tissue-type plasminogen activator in an in vitro model of catheter-assisted thrombolysis

Abstract

Summary. Plasmin, the direct fibrinolytic enzyme, was compared with tissue plasminogen activator (t‐PA) in an in vitro thrombolysis model. Plasmin has been prepared in a highly pure form from human plasma and has been stabilized against auto‐degradation by low‐pH formulation. This acidified formulation of plasmin has been designed to have a low buffering capacity so that it can be directly infused into clots in a stable and latently active form. This low‐pH formulation has been shown to be equivalent to a neutral‐pH formulation of plasmin in its extent of clot lysis. An in vitro model of catheter‐assisted thrombolysis has been devised in which large (12 × 0.6 cm), retracted clots are treated with an intrathrombus thrombolytic agent via a multi‐sideport catheter. Plasmin dissolves these plasminogen‐deficient clots in a dose‐dependent manner and is clearly superior to t‐PA. In this model system, t‐PA exhibits efficacy only when retracted clots are replenished with plasminogen.

Accelerating thrombolysis with chitosan-coated plasminogen activators encapsulated in poly-(lactide-co-glycolide) (PLGA) nanoparticles

“…The encapsulation efficiencies of t-PA in NPs are generally unrelated to particle size and zeta potentials, both with or without coating (Table 1). For comparison, the t-PA encapsulation efficiency of PLGA NPs (65.4774.08%) fabricated herein significantly exceeds those of urokinase (e.g., 11.6%) and SK (e.g., 30.0%)-encapsulated liposomes of similar sizes (200 nm [25] and 339 nm [11]). These results suggest that t-PA is more efficiently encapsulated in PLGA NPs than in liposomes.…”

“…These include intrathrombotic injection of PA or acid-stabilized plasmin [29,30] and the use of ultrasound and micro-bubbles [31]. However, the intra-thrombotic injection of PA can be performed only by highly trained personnel, who must use specialized imaging equipment, and the production and purification of acid-stabilized plasmin involves a complex chemical process to prevent auto-degradation and loss of activity of plasmin at physiological pH [30].…”

“…These include intrathrombotic injection of PA or acid-stabilized plasmin [29,30] and the use of ultrasound and micro-bubbles [31]. However, the intra-thrombotic injection of PA can be performed only by highly trained personnel, who must use specialized imaging equipment, and the production and purification of acid-stabilized plasmin involves a complex chemical process to prevent auto-degradation and loss of activity of plasmin at physiological pH [30]. Although enhancement of fibrinolysis in vitro has been found after clots were exposed to 2 MHz ultrasound, galactose-based microbubbles and t-PA in buffer solution for 30 min, the ratio of maximum weight of the digested clot to the initial clot was 30.779.5% [31].…”

Direct fibrinolytic agents: biochemical attributes, preclinical foundation and clinical potential

“…Bacterial expression systems have not been successful for recombinant plasminogen production, and eukaryotic expression is limited by cytotoxicity resulting from intracellular plasminogen activation, but expression in insect cells has been achieved [37], as has high-yield production of full-length transgenic plasminogen in a duckweed expression system [38]. A low-pH, low buffering capacity formulation of plasmin, which is protected from autodegradation and allows infusion in a stable, latent form that reactivates upon exposure to neutral pH in plasma, has been prepared (Talecris Biotherapeutics, Inc., Research Triangle Park, NC, USA) [39].…”

Middle Cerebral Artery Occlusion in the Rabbit Using Selective Angiography

“…There was minimal flow of thrombin into the right anterior cerebral artery (ACA), which filled from the contralateral ACA via the anterior communicating artery. Plasmin (Talecris Biotherapeutics) 1 was reconstituted as 1 mg/mL sterile nonbuffered saline, and administered just proximal to the MCA occlusion. Angiography was performed to document MCA occlusion and recanalization.…”