Fibrinolytic mechanism, biochemistry, and preclinical pharmacology of recombinant prourokinase

Reversal of intraoperative arterial thrombosis with a fibrinolytic agent when treating large and giant partially thrombosed aneurysms of the middle cerebral artery

OBJECT

Thrombosis of the cerebral arteries is one of the complications of microsurgical operations for partially thrombosed intracranial aneurysms. The object of this study was to assess the frequency of intraoperative arterial thrombosis (IAT) during microsurgical treatment of large and giant partially thrombosed aneurysms of the middle cerebral artery (MCA) and also to assess the efficacy of the treatment of this complication.

MATERIALS

The authors analyzed a consecutive series of 53 patients who underwent surgery for partially thrombosed aneurysms of the MCA at the Burdenko Neurosurgical Institute between January 2005 and September 2014. Thirty-two patients had large aneurysms (15–25 mm) and 21 had giant aneurysms (> 25 mm). Clipping of aneurysms was performed in 47 patients, trapping was performed in 3, and wrapping was performed in 3.

RESULTS

IAT was diagnosed in 10 patients (18.9%). The authors describe a technique for IAT reversal involving the injection of modified human recombinant prourokinase (mr-proUK). Of the 7 patients who underwent injection of mr-proUK in the thrombosed artery, 5 (71.4%) were discharged without any change in neurological status, 1 (14.3%) experienced moderate deterioration (modified Rankin Scale [mRS] score of 2), and 1 (14.3%) experienced severe deterioration (mRS score of 4). Among the 3 patients who had complications and did not receive an injection of mr-proUK, 2 experienced severe deterioration (mRS score of 3 and 4) and 1 had moderate deterioration (mRS score of 2).

CONCLUSIONS

The primary risk factor of thrombectomy with temporary trapping is thrombosis in the MCA branches. The injection of a fibrinolytic agent into thrombosed MCA branches is an effective method for the treatment of IAT.

The expression of proUK in Escherichia coli: the vgb promoter replaces IPTG and coexpression of argU compensates for rare codons in a hypoxic induction model

The expression of the proUK gene was improved by the coexpression of the argU gene cloned in a moderate copy number vector. As the proUK gene contains 2% AGG/AGA codons, which is much higher than the normal frequency in E. coli, about 0.14%-0.21%, the argU gene cloned in a multicopy plasmid was coexpressed with the proUK expression vector in our experiments. In E. coli strain BL21(DE3), IPTG is known to induce the expression of T7 RNA polymerase gene and this enzyme can transcribe the proUK gene under the control of the T7 promoter leading to expression of proUK. To replace IPTG by a cheaper alternative on a large scale, we constructed a plasmid in which the vgb promoter--which is known to be activated by the onset of hypoxic conditions--controls the T7RNA polymerase gene expression. Low oxygen conditions were then used to activate the vgb promoter causing T7RNA polymerase gene expression and finally leading to the expression of proUK as inactive inclusion bodies. Our experiments on a large scale in a bioreactor show that the expression of proUK accounts for about 30% of total protein after about 6 h of anaerobic cultivation, so the presented model represents an economical alternative to IPTG induction.