Effect of ranelate-covered gold nanoparticles injection on microcirculation of mice.

Abstract

Nanotechnology is proving to be a very promising area, enabling new approaches with particularities capable of overcoming pre-existing limitations in various fields, generating optimistic expectations. This advance has contributed to the development of new products, including those intended for the maintenance of the health of individuals. In this context, nanoparticles (NPs), which are compounds that have all their dimensions between one and one hundred nanometers in size, have been extensively researched to be used as medicines. For example, gold nanoparticles (AuNPs), are easily synthesized in different sizes and are compatible for conjugation with various molecules. Among these, citrate-coated gold nanoparticles (AuNP-cit) are the most common ones and have been reported to confer intrinsic therapeutic properties in recent years. However, AuNPcit are relatively unstable, i.e., they tend to aggregate over time, increasing their size and thus altering their properties. Ranelate-gold nanoparticles (AuNP@Ran) have recently emerged with the potential to improve this aspect. They were developed at the Chemistry Institute of the University of São Paulo, by professor Henrique Toma's group. AuNP showed a strong reaction with ranelate to generate stable nanoparticles. Despite some data showedAuNP@Ran did not cause toxic effects in a macrophage cell culture lineage, it is not known whether these compounds cause an harm when administered at or near therapeutic concentrations in vivo, in the microcirculation, a site where the innate immune system acts to recruit defense cells, control the vascular permeability and blood hemostasis. Thus, we will measure the effect of different doses of AuNP@Ran on the microcirculation of mice. To do this, we will observe the cremaster muscle of C57Bl/6 male mice before and every 15 minutes up to 45 minutes after AuNP@Ran injection. The following parameters will be measured:: rolling, adhesion, and leukocyte migration. In addition, coagulation parameters will be measured, in vivo, particularly, initial time for thrombus formation and time for thrombus-induced blood vessel occlusion, along with prothrombin (PT) and activated partial thromboplastin (aPTT) times, and fibrinogen concentration, using commercial kits. Leukogram and platelet count, expression of adhesion molecules in leukocytes (ICAM-1 and beta2-integrin) and platelets (±2b²3 integrin) by flow cytometry, expression of ICAM-1, eNOS and COX-2 in cremaster muscle by Western blotting, and expression of thromboxane B2 and MDA in cremaster muscle by ELISA will also be performed.