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28-03-2011 | Cardiology | Article

Targeting novel protein may improve thrombolysis


Free abstract

MedWire News: French researchers suggest that protease nexin-1 (PN-1) may be an important regulator of thrombolysis.

Inhibition of the platelet component PN-1 by antibodies or synthetic compounds may improve the therapeutic efficacy of thrombolytic agents, they say.

PN-1, also known as SERPINE2, is serum protease inhibitor that accumulates at vascular injury sites and inhibits urokinase plasminogen activator, tissue plasminogen activator (tPA), plasmin, and thrombin, explain Marie-Christine Bouton (CHU Xavier Bichat, Paris) and colleagues.

Because of its action on plasma proteases, Bouton and team hypothesized that PN-1 may play a prominent role in thrombolysis resistance.

To investigate, the researchers carried out a series of in vitro and in vivo studies. They demonstrate that PN-1 inhibits plasmin generation by fibrin-bound tPA, and fibrinolysis induced by fibrin-bound plasmin.

They also found that that in the absence of PN-1, endogenous tPA-induced clot lysis increased within 24 hours, indicating that PN-1 is a regulator of endogenous clot lysis.

To determine whether the antifibrinolytic effect of PN-1 also occurs in vivo, Bouton and team developed a microscopy-based method to measure thrombolysis in mice.

First they used FeCl3 to induce vascular injury and thrombosis in the mice. They then treated wild-type (WT) and PN-1 deficient (PN-1-/-) mice with tPA to induce thrombolysis.

The team observed that the mean time to recanalization was longer than 1 hour in the WT mice but only 13 minutes in the PN-1-/-animals. Furthermore, only 15% of WT mice exhibited complete recanalization compared with 92% of PN-1-/-mice.

Thirty minutes after tPA treatment, thrombus size remained unchanged in WT mice (101.6% of initial size), but fell significantly in the PN-1-/-mice (56.1% of initial size).

"Considered together, these results confirm that PN-1 is a potent inhibitor of tPA-induced thrombolysis in vivo," write Bouton and co-authors in the journal Circulation.

Therefore, "inhibition of PN-1 is predicted to promote endogenous and exogenous tPA-mediated fibrinolysis and may enhance the therapeutic efficacy of thrombolytic agents," they conclude.

MedWire ( is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2011

By Laura Dean

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