In the present study, we investigated anti-thrombotic effects of W007B, a water-soluble derivative of honokiol, with different models both in vitro and in vivo. Rat platelet aggregation was induced by adenosine diphosphate （ADP）, thrombin, arachidonic acid （AA） and collagen in vitro. The anti-thrombotic effects were evaluated with the arterio-venous shunt model, electrode-stimulated carotid thrombosis model in rats and ADP-induced acute pulmonary embolic model in mice. The bleeding time in vivo was examined with tail incision in mice. W007B inhibited ADP-, thrombin-, collagen- and AA-induced platelet aggregation in a concentration-dependent manner, with an ICs0 value of 899.5 μM, 212.9 μM, 266.0 μM and 52.5 μM, respectively. In vivo, W007B （2-10 mg/kg, ig） significantly reduced the thrombus weight in the model of arterio-venous shunt. Besides, W007B could effectively prolong the occlusion time in the electrode-stimulated carotid thrombosis model. Moreover, in the ADP-induced acute pulmonary embolism model in mice, 2.8-14 mg/kg of W007B significantly reduced the death of mice. In conclusion, W007B is effective on platelet aggregation, and it is most sensitive on AA-induced aggregation. W007B has potent anti-thrombotic effect on different arterial thrombosis models. It may be an orally active candidate of anti-thrombotic agents.
Recombinant tissue plasminogen activator （rPA） has been used as a thrombolytic agent. However, considerable improvements have been done to prolong its plasma half-life （tl/2） and reduce its side effects, such as intracranial hemorrhage. Based on these improvements, a mutant ofrPA, mrPA, was designed by mutating its PAI-1 binding site to extend its tl/2. Furthermore, a fusion protein conjugating mrPA with NR3 was designed, which was a rAcAp5 mutant with a platelet GPIIb/IIIa-binding RGD motif, to enhance the ability of targeted-thrombus and thrombolysis. The synthesized DNA sequences coding the two proteins were amplified by PCR, cloned into pET30a to construct recombinant plasmids pET30a-mrPA and pET30a-mrPA-NR3, and transformed into E. coli BL21 （DE3）. The two proteins were expressed in inclusion bodies induced by isopropy113-D-1-thiogalactopyranoside. After purified to qualified purity using one-step Ni affinity chromatography, the denatured proteins were refolded by dialysis. Their thrombolytic effects in vitro and in vivo were evaluated. In vitro 3.5 and 7 pmol/L of mrPA significantly reduced thrombus weight; 1.75, 3.5 and 7 ~tmol/L of mrPA-NR3 also significantly reduced the thrombus weight, and mrPA-NR3 displayed stronger thrombolytic effects than mrPA at 7 lamol/L. In vivo both mrPA and mrPA-NR3 showed significantly thrombolytic effect at 60-240 ktmol/kg in thrombolytic model of inferior vena cava. Importantly, mrPA-NR3 exhibited more potent thrombolytic effect than both mrPA and rhM-tPA （positive control） at 240 p.mol/kg. In addition, these two novel proteins did not increase bleeding time while they exerted thrombolytic effect. In conclusion, we engineered two novel proteins and proved that fusion protein had better thrombolytic effect than non-fusion protein, and the results suggest that dual thrombolytic mechanism or thrombus-target potentiated the thrombolytic effect ofrPA and alleviated hemorrhage side reaction. This study may shed light on the development of novel thrombolytic agents
Recombinant ancylostoma caninum anticoagulant peptide-5 （rAcAP5） has been reported to inhibit thrombin-activatable fibrinolysis inhibitor （TAFIa） activity and have thrombolytic effect. The present study was to screen a strain expressing high-yield of rAcAP5 and to assess its thrombolytic effect on embolic middle cerebral artery occlusion （MCAO） model in rats. Codons encoding for AcAP5 were optimized. Six expression plasmids and eleven E. coli strains with different characteristics were used, a total of 66 recombinant expression strains were generated and the one with the highest yield was selected to express rAcAP5, which was purified through anion- and cation-exchange chromatography. The purity of rAcAP5 and its molecular weight were determined by HPLC and mass spectrometry, respectively. The thrombolytic effect of rAcAP5 was evaluated on embolic MCAO model in rats; regional cerebral blood flow （rCBF） was monitored with a Laser-Doppler flowmetry to test the occlusion and recanalization of MCA. The highest yield recombinant strain was C2566H/pTYB 1-rAcAP5. AcAP5 （28 mg） with 90% of purity was obtained from 1 L of cell culture. In rat embolic MCAO model, vehicle （normal saline） treatment did not change the rCBF, while treatment with rAcAP5 （50-200 μg/kg, i.v.） increased the rCBF in a dose-dependent manner. In conclusion, we prepared and characterized the rAcAP5 peptide and revealed its thrombolytic effect in embolic MCAO model and our results suggested that this peptide had the potential to be used as a thrombolytic agent.
