New derivative of staphylokinase SAK-RGD-K2-Hirul exerts thrombolytic effects in the arterial thrombosis model in rats
Comparative study published in Pharmacological reports : PR (2011)
Abstract
SAK-RGD-K2-Hir and SAK-RGD-K2-Hirul are recombinant proteins that are derivatives of r-SAK (recombinant staphylokinase). They are characterized by their fibrin-specific plasminogen activation properties and their antithrombin and antiplatelet activities. The difference between these proteins is the presence of the antithrombotic fragment (hirudin or hirulog) in the C-terminal portion of the r-SAK. The aim of the present study was to examine the thrombolytic potentials of SAK-RGD-K2-Hir and SAK-RGD-K2-Hirul in an electrically induced carotid artery thrombosis model in rats and to compare the potentials to that of r-SAK. We determined that a bolus injection of SAK-RGD-K2-Hirul was more effective than one of r-SAK in the improvement and maintenance of carotid patency and in arterial thrombus weight reduction; however, it had the same potency as SAK-RGD-K2-Hir. The bleeding time, prothrombin time and activated partial thromboplastin time were significantly prolonged in the animals that were treated with either dose (1.5 or 3.0 mg/kg) of SAK-RGD-K2-Hir or SAK-RGD-K2-Hirul, whereas no changes were observed in the plasma fibrinogen concentration or the α2 plasmin inhibitor level. r-SAK alone did not change the bleeding time or coagulation parameters. In conclusion, our findings demonstrate the thrombolytic activity of intravenous bolus injection of the novel thrombolytic agent SAK-RGD-K2-Hirul in rats. Although this protein compares favorably with r-SAK, we were unable to show the presence of any beneficial effects of SAK-RGD-K2-Hirul over those of SAK-RGD-K2-Hir. Furthermore, our results suggest that high doses of SAK-RGD-K2-Hirul bear the risk of bleeding.
Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.
Summary
SAK-RGD-K2-Hir and SAK-RGD-K2-Hirul are recombinant proteins that are derivatives of r-SAK (recombinant staphylokinase).
Why This Matters for Hirudotherapy
This study examined the thrombolytic potential of a recombinant staphylokinase derivative, SAK-RGD-K2-Hirul, which incorporates a hirulog (hirudin-derived) antithrombotic fragment, in an electrically induced carotid artery thrombosis model in rats. A bolus injection of SAK-RGD-K2-Hirul was more effective than r-SAK alone in improving carotid patency and reducing thrombus weight, comparable to the hirudin-fragment-containing SAK-RGD-K2-Hir, but high doses carried bleeding risk. This demonstrates the functional contribution of a hirudin-derived peptide within a multimodal thrombolytic fusion protein, relevant to hirudin-based antithrombotic drug design. Caveat: this is an animal (rat) study of a recombinant fusion protein, not natural hirudin or live leech therapy, and no advantage over the hirudin-fragment variant was shown.
Citation
New derivative of staphylokinase SAK-RGD-K2-Hirul exerts thrombolytic effects in the arterial thrombosis model in rats
Szemraj J et al. · Pharmacological reports : PR, 2011
Added to ASH library: May 27, 2026 · Site last updated: June 18, 2026