In vitro evaluation of thrombogenicity effect of gallium-containing mesoporous bioactive glass

Abstract

Event Abstract Back to Event In vitro evaluation of thrombogenicity effect of gallium-containing mesoporous bioactive glass Sara Pourshahrestani1, Ehsan Zeimaran1, Nahrizul A. Kadri1 and Mark R. Towler1, 2 1 University of Malaya, Department of Biomedical Engineering, Malaysia 2 Ryerson University, Department of Mechanical & Industrial Engineering, Canada Introduction: Inorganic hemostats have demonstrated effectiveness in staunching bleed out[1]. Mesopororus bioglasses (MBGs) are promising candidate for hemorrhage control due to their high specific surface area, pore volume and pore size[2]. Gallium nitrate has proven efficacy in stimulation of the early stages of hemostasis (either coagulation, platelet activation, or thrombus formation)[3]. In this paper, MBGs containing three different concentrations of Ga2O3 (1, 2 & 3 mol %) were synthesized and the effect of Ga3+ addition to the MBG framework on in vitro thrombogenicity of MBG was evaluated. Methods: Three MBGs (80-x) %SiO2–15%CaO–5%P2O5–xGa2O3 doped with different content of Ga2O3 were synthesized via evaporation-induced self-assembly (EISA) process by using Pluronic P123 as a mesostructure former. Briefly, Pluronic P123, tetraethyl orthosilicate (TEOS), Ca(NO3)2.4H2O, triethyl phosphate (TEP), Ga(NO3)3. X H2O and 0.5 M HNO3 were dissolved in ethanol and then stirred overnight and the sol underwent the EISA process for one week. The dried gels were calcinated at 600°C for 5 h. The textural properties of the prepared materials were determined by N2 adsorption/desorption analyses using a Micrometrics ASAP 2020 instrument. The surface area and pore size distribution were determined by applying the Brunauer–Emmett–Teller (BET) and the Barret–Joyner–Halenda (BJH) methods respectively. To test the in vitro thrombotic effect, the materials were incubated with citrated human blood for 15, 30 and 60 min at 37 °C. The degree of thrombogenicity (DT) of the materials was defined as follows: DT = [(Wt-W0)/W0] × 100%, where W0 and Wt are the weights of the samples before and after incubation with blood, respectively. Field-emission scanning electron (FESEM: Quanta™ 250 FEG—FEI, USA) micrographs were also obtained to observe the interaction of whole blood with the Ga-MBG materials. Results and Discussion: Table 1 demonstrates the BET, pore volume and pore size of MBG and Ga-MBG samples. Notably, the surface area and pore volume of the 1%Ga-MBG were found to be higher than those of other samples. As can be seen in Figure 1a, with increasing incubation time, the thrombus formation on the surface of 1%Ga-MBG increased greatly with respect to MBG. FESEM images shows that in comparison to MBG (Figure. 1b), more red blood cells (RBCs) were aggregated on 1%Ga-MBG surface (Figure. 1c) and coalesced into an erythrocyte plug surrounded by a mesh of cross-linked fibrin strands. The thrombogenic activity of the 1%Ga-MBG could be explained as owing to the synergy of both its higher specific surface area and pore volume that provide more space for trapping blood plasma components combined with the presence of Ga3+ which may lead to polymerization of fibrinogen into strong fibrin clots and subsequent stimulation of blood coagulation cascade. The abundant presence of silanol groups on 1%Ga-MBG surface that bind with the phosphatidyl choline-rich RBC membrane, can be also involved in higher thrombogenic potential of 1%Ga-MBG[4]. Conclusion: This study suggests that the MBG with lowest amount of Ga2O3 could be considered as a promising candidate for hemostatic application as showed great thrombotic effect in vitro. However, there is a growing need to investigate the capability of the materials to produce a stable clot in vivo. This research is supported by a High Impact Research MoE Grant (UM.C/625/1/HIR/MoE/ENG/58) from the Ministry of Higher Education Malaysia and University of Malaya Research Grant (UMRG, RG156-12AET).