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Purification and characterization of mutant miniPlasmin for thrombolytic therapy.

ABSTRACT: BACKGROUND:Previous animal studies by us and others have indicated that catheter-administered plasmin or its des-kringle derivatives may be more appropriate alternatives to plasminogen activators for treating thrombolytic diseases, since it has a very short serum half-life and therefore does not result in hemorrhaging. We have previously produced recombinant miniPlasmin (mPlasmin) that was proven suitable for treating peripheral arterial occlusion in animal models. However, our previous results showed that non-specific cleavage at position K698 of mPlasmin during activation hindered the further development of this promising therapeutic candidate. In order to minimize or eliminate the non-specific cleavage problem, we performed saturation mutagenesis at the K698 position to develop a mutant form of mPlasmin for thrombolytic therapy. METHODS:We changed K698 to 16 other amino acids, with preferred E. coli codons. Each of these mutants were expressed in E. coli as inclusion bodies and then refolded, purified, and subsequently characterized by detailed kinetic assays/experiments/studies which identified highly active mutants devoid of non-specific cleavage. RESULTS:Activation studies indicated that at those conditions in which the wild type enzyme is cut at the non-specific position K698, the active mutants can be activated without being cleaved at this position. CONCLUSIONS:From the above results, we selected two mutants, K698Q and K698N, as our lead candidates for further thrombolytic drug developments. The selected mutants are potentially better therapeutic candidates for thrombolytic therapy.

SUBMITTER: Lin X

PROVIDER: S-EPMC3724493 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature

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Purification and characterization of mutant miniPlasmin for thrombolytic therapy.

Lin Xiaotao X Wang Yan Y Zhang Yanwen Y Huang Bing B Lin James J JJ Hallock Scott J SJ Yu Hong H Shao Hongwei H Yan Jing J Huang Bo B Zhang Xuejun C XC Cao Wei W Xu Xueming X Lin Xinli X

Thrombosis journal 20130130 1

<h4>Background</h4>Previous animal studies by us and others have indicated that catheter-administered plasmin or its des-kringle derivatives may be more appropriate alternatives to plasminogen activators for treating thrombolytic diseases, since it has a very short serum half-life and therefore does not result in hemorrhaging. We have previously produced recombinant miniPlasmin (mPlasmin) that was proven suitable for treating peripheral arterial occlusion in animal models. However, our previous ...[more]

PMID: 23363549

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Project description:RationaleCurrent thrombolytic agents activate plasminogen to plasmin which triggers fibrinolysis to dissolve thrombi. Since plasmin is a nonspecific proteolytic enzyme, all of the current plasmin-dependent thrombolytics lead to serious hemorrhagic complications, demanding a new class of fibrinolytic enzymes independent from plasmin activation and undesirable side effects. We speculated that the mammalian version of bacterial heat-shock proteins could selectively degrade intravascular thrombi, a typical example of a highly aggregated protein mixture.ObjectiveThe objective of this study is to identify enzymes that can dissolve intravascular thrombi specifically without affecting fibrinogen and fibronectin so that the wound healing processes remain uninterrupted and tissues are not damaged. In this study, HtrA (high-temperature requirement A) proteins were tested for its specific proteolytic activity on intravascular thrombi independently from plasmin activation.Methods and resultsHtrA1 and HtrA2/Omi proteins, collectively called as HtrAs, lysed ex vivo blood thrombi by degrading fibrin polymers. The thrombolysis by HtrAs was plasmin-independent and specific to vascular thrombi without causing the systemic activation of plasminogen and preventing nonspecific proteolysis of other proteins including fibrinogen and fibronectin. As expected, HtrAs did not disturb clotting and wound healing of excised wounds from mouse skin. It was further confirmed in a tail bleeding and a rebleeding assay that HtrAs allowed normal clotting and maintenance of clot stability in wounds, unlike other thrombolytics. Most importantly, HtrAs completely dissolved blood thrombi in tail thrombosis mice, and the intravenous injection of HtrAs to mice with pulmonary embolism completely dissolved intravascular thrombi and thus rescued thromboembolism.ConclusionsHere, we identified HtrA1 and HtrA2/Omi as plasmin-independent and highly specific thrombolytics that can dissolve intravascular thrombi specifically without bleeding risk. This work is the first report of a plasmin-independent thrombolytic pathway, providing HtrA1 and HtrA2/Omi as ideal therapeutic candidates for various thrombotic diseases without hemorrhagic complications.

Project description:BackgroundSpecific clinical risk factors may contribute to improving or worsening neurological functions in acute ischemic stroke (AIS) patients pre-treated with a combined cholesterol reducer and recombinant tissue plasminogen activator (rtPA) therapy. In this study, clinical risk factors associated with good or poor presenting neurological symptoms in ischemic stroke patients with prior cholesterol reducer use, specifically a statin and rtPA therapy was investigated.MethodsRetrospective data for baseline clinical and demographic data for patients with AIS taking cholesterol reducers prior to rtPA treatment from January 2010 to June 2016 in a regional stroke center was analyzed. Improving (NIHSS score ≤ 7) or worsening (NIHSS score > 7) of neurologic functions were the determined measures of treatment outcome. Multivariate logistic regression models identified demographic and clinical factors associated with worsening or improving neurologic functions.ResultsAdjusted multivariate analysis showed that in an AIS population with a combined rtPA and cholesterol reducer medication history, increasing age (OR = 1.032, 95% CI, 1.015-1.048, P < 0.001) and atrial fibrillation (OR = 1.859, 95% CI, 1.098-3.149, P = 0.021) demonstrated a likely association with worsening neurologic functions, while direct admission (OR = 0.411, 95% CI, 0.246-0.686, P = 0.001) and being Caucasian (OR = 0.496, 95% CI, 0.297-0.827, P = 0.007) showed an association with improving or progressing neurologic functions.ConclusionA prior cholesterol reducer, namely a statin, plus rtPA combination may be associated with worsening neurological function for elderly AIS patients with atrial fibrillation, while Caucasians directly admitted to a neurology unit are more likely to show an association with progress or improvements in neurologic functions. While combining statin with rtPA treatment may facilitate worsening neurologic functions in elderly AIS patients with atrial fibrillation, they should not be denied of this therapy. The decision to combine statin and rtPA for AIS patients with atrial fibrillation can be done after clinical stabilization following appropriate clinical management.

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Purification and characterization of mutant miniPlasmin for thrombolytic therapy.

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Purification and characterization of mutant miniPlasmin for thrombolytic therapy.

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