Molecular weight dependent heparin inhibition of endothelial cell stimulation by FGF-2 and VEGF

[Enoxaparin is a low-molecular-weight heparin with a complex chemical structure and various non-anticoagulant properties]

The paper discusses the non-anticoagulant properties of unfractionated heparin and enoxaparin and their relation to their chemical structures. It is emphasized that enoxaparin has multiple, often interrelated, non-anticoagulant effects that can complement its antithrombotic activity and enhance the efficiency of therapy in patients receiving the drug for various indications. The realization of these effects requires the complex structure with the standard distribution of molecular weight (Mw) (average Mw, about 4500 Da, as well as Mw of less than 2000 Da (<20%), 2000 to 8000 Da (>68%), and more than 8000 Da (<18%), and with the standard content of 1.6-anhidro rings (15-25%), which is determined by the source of raw materials and by the production technology of the original drug and cannot be fully reproduced when designing its bioanalogues.

Antiproliferative effects of low molecular weight heparin

AIM

To investigate the effect of low molecular weight heparins (LMWH) on the inhibition of intimal hyperplasia (IH) developing in prosthetic vascular patch graft implanted into sheep carotid artery.

METHODS

A gelatin sealed Dacron patch graft was implanted into the common carotid artery of sheep, which were then allocated to a control group (n = 10) or to one of four treatment groups (each group n = 10) receiving either a low dose (LD) or high dose (HD) of one of two LMWH (enoxaparin 1 or 2 mg/kg/day, dalteparin 100 or 200 units/kg/day) administered subcutaneously for 4 weeks. Anti-activated factor X and activated partial thromboplastin time were assayed from blood collected prior to and at 1 and 2 h after LMWH administration on days 3, 7, 14, 21 and 28. Animals were killed on day 28 after taking blood samples prior to, then at 0.5, 1, 2, 3, 4, 6, 8, 12 and 24 h following the last injection. Grafts were collected for analysis and measurements of intimal thickness obtained under light microscopy from eight transverse sections of each grafted artery aided by computer image analysis. An IH index was calculated by dividing the area of IH (mm2) by the width of the graft (mm).

RESULTS

Intimal hyperplasia index measurements (mean +/- SD) were: controls 0.574 +/- 0.077, LD enoxaparin 0.471 +/- 0.056, LD dalteparin 0.404 +/- 0.025, HD enoxaparin 0.398 +/- 0.068, HD dalteparin 0.332 +/- 0.048. The reductions in IH index compared to controls were significant (P < 0.05) for both LD and HD dalteparin and for HD enoxaparin.

CONCLUSION

Both LMWH dalteparin and enoxaparin reduced the amount of IH formation with dalteparin showing a greater effect in the present animal study. The possibility that different LMWH might exert differing antiproliferative effects requires further investigation.