The effects of copper manganese and mercury alone and in combinations in an ex vivo model of coagulation

Abstract

Pollution is increasing rapidly due to anthropogenic activities and daily contact with metals is a reality. Metals at certain levels can have a negative effect on the health of an individual and can cause alterations in the coagulation system, which may result in cardiovascular system complications. The aim of this project was to investigate the effects of copper, manganese and mercury, alone and in combinations, using an ex vivo model of coagulation by using the haemolysis assay, scanning electron microscopy and thromboelastography®. These metals were chosen as there is an increase in exposure to these metals by the general public, but more specifically individuals living in rural areas, of South Africa due to pollution. The concentrations used were based on the World Health Organisation safety limit for each respective metal; e.g. copper X100 indicates the blood is exposed to a copper level that is 100 times greater than that of the safety limit set out for the metal according to the World Health Organisation. This investigation was conducted at the cell biology laboratory and the Unit of Microscopy and Microanalysis at the University of Pretoria. The various constituents of blood showed different sensitivities to different metal groups. Manganese and mercury showed the highest haemolytic effects at higher concentrations. Synergism was only observed between the double combination groups of manganese and mercury (X100) and manganese and copper (X1000) as well as in the triple combination group (X100). Copper caused haemoglobin precipitation at higher concentrations. At low concentrations copper and copper combinations induced met- and sulfhaemoglobin formation, especially the copper and manganese combination at X10 concentration which increased met- and sulfhaemoglobin by about 5 – 10%. The degree of echinocyte formation was greatest in copper, but the combination of manganese and copper had the greatest impact on erythrocyte morphology. Activation and necrosis of platelets were most evident at the highest mercury concentration. All double metal combinations caused platelet interactions and aggregation. Novel findings indicated that at X1, manganese caused the formation of net-like structures of thin fibres and sticky masses of thick fibres with fused areas. In combination with copper and mercury, a similar effect was observed, however, in the triple combination group a lesser effect was observed. No statistically significant changes were observed in the measured coagulation parameters for thromboelastography®, however, trends were observed compared to the control. These were a decrease in reaction time, a decrease in kinetics, an increase in angle, an increase in maximum amplitude, an increase in maximum rate of thrombus generation, an increase in thrombus generation and either increased or reduced time to maximum rate of thrombus generation. These trends indicate a more hypercoagulable state of blood. All the metals, in their own way, had an effect on the coagulation system, resulting in an increase in the likelihood of thrombosis which will contribute to cardiovascular diseases.