Dendrigraft of Poly-l-lysine as a Promising Candidate To Reverse Heparin-based Anticoagulants in Clinical Settings

Abstract

By using a combination of experimental and computational experiments, we demonstrated that a second-generation dendrigraft of poly-l-lysine neutralizes the anticoagulant activity of unfractionated heparin, low-molecular-weight heparin, and fondaparinux more efficiently than protamine does in human plasma, making this synthetic polymer a promising surrogate of this problematic protein in clinical settings.

Figure 1

Top left: major heparin disaccharide repeat unit. Top right: sequences of four major protamine components P1–P4 extracted from salmon sperm with basic amino acids underlined, see ref (15). Bottom: schematic representation of first- to fifth-generation DGLs G1–G5, where each dot represents an l-lysine residue. For a comprehensive study of DGLs’ three-dimensional structural features from experimental and computational experiments, see ref (16).

Figure 2

Neutralization by various antidotes of three different clinically used heparins at therapeutic concentrations (UFH, 0.3 U/mL; enoxaparin, 0.4 U/mL; fondaparinux, 1.1 U/mL) in human plasma from anti-Xa assays.

Figure 3

Representative snapshots taken at the end of the MD trajectories for fondaparinux (A), enoxaparin (B), UFH (C), and the stoichiometric complexes DGL G2:fondaparinux (D), DGL G2:enoxaparin (E), DGL G2:UFH (F), protamine:fondaparinux (G), protamine:enoxaparin (H), and protamine:UFH (I). Heparins are represented as balls, and antidotes as sticks. For the full set of computed complexes, see the Supporting Information.

Figure 4

Charge-normalized free energy of binding values ΔG_bind,eff and average number of electrostatic interactions per frame N_eff for the 36 complexes studied by MD simulations. For each antidote:anticoagulant pair, circles refer to the individual ΔG_bind,eff values, and the black line to the corresponding mean value.