Effect of Biopolymers and Functionalized by Them Vaterite Microparticles on Platelet Aggregation

Vaterite microparticles, metastable form of calcium carbonate,are promising forms of delivery of medicinal compounds. For moreefficient delivery of target molecules (increased incorporationand retention), vaterite microparticles must be functionalized withbiopolymers. In this article the effect of polysaccharides, mucinand vaterite microparticles, as well as hybrid vaterite microparticleswith the above-mentioned biopolymers was studied on platelet aggregation.It was found that fucoidan, heparin and dextran sulfate (when addedto platelet-rich plasma) and mucin (when added to isolated platelets) initiatedcell aggregation. Pectin and chondroitin sulfate inhibited ADP-and thrombin-induced aggregation in a dose-dependent manner, mucinsuppressed ADP-induced, and dextran sulfate suppressed thrombin-inducedplatelet aggregation. Vaterite microparticles at a concentrationof 100–1000 µg/mL did not affect the aggregation of isolated platelets,but caused 10–15% cell aggregation in plasma; at the same time,at a concentration of 1000 µg/mL vaterite microparticles preventedagonist-induced cell aggregation by ~30%. It has been establishedthat hybrid vaterite microparticles with fucoidan or heparin, whenadded both to platelet-rich plasma and to isolated cells, are capableto initiate platelet aggregation. Vaterite microparticles functionalizedwith pectin or chondroitin sulfate had no effect on spontaneouscell aggregation, and did not affect (with chondroitin sulfate)or inhibit (with pectin) agonist-induced platelet aggregation. Thus,the use of hybrid vaterite microparticles with pectin or fucoidan/heparinmay be promising for the delivery of drugs aimed at modulating (inhibitionwith pectin or activation with fucoidan/heparin) the platelet componentof hemostasis.