Cobalt induced cardiotoxicity : a suspected adverse effect associated with COCR alloy orthopaedic implants

  • Sarunya Laovitthayanggoon

Student thesis: Doctoral Thesis

Abstract

Cobalt toxicity, arising from the release of metal nanoparticles and ions during wear of Co/Cr metal-on-metal (MoM) hip implants has become a recognised internal source of Co poisoning. Co ions enter the bloodstream during wear and corrosion processes of MoM implants, and then travel throughout the body causing systemic toxicity. Cardiac toxic manifestations have been shown to be among the most prevalent systemic symptoms following exposure.In this thesis we have investigated the effects of short and/or long term CoCl2 exposure on the Swiss 3T3 fibroblast cell line (3T3s) and primary adult cardiac fibroblasts (CFs) in vitro. We have measured effects on cell viability, morphology, proliferation, assessed intracellular Co uptake, and detected and quantified protein expression by western blotting. Further, we also studied the effects of chronic in vivo CoCl2 treatment (4 weeks of daily 1mg/kg intraperitoneal injections) of rats carrying out echocardiography, and determining the Co distribution into various organs.The expression of potential transporter proteins, TRPC6, TRPM7, DMT1, and of CAMKIIδ, a serine/threonine kinase with pivotal roles in cardiovascular function through regulation of Ca2+ handling and excitation-contraction coupling, were also investigated. To complete the in vitro and in vivo studies, the molecular mechanism(s) underlying the overall changes were screened by RNA-Seq analysis, and gene expression was subsequently validated by quantitative real-time-PCR (RT-qPCR) and western blotting.In terms of proliferation of 3T3 cells and CFs treated with CoCl2, the CFs were much more sensitive than 3T3 cells with IC50 values for CoCl2 in the range of ~20 μM inCFs and ~250 μM in 3T3 cells. Using phalloidin to stain the actin inside cells showed that in both types of cells actin fibres were disrupted, and the membrane formed blebs at high Co concentrations. Co uptake, evaluated at the cellular level by using inductively coupled plasma mass spectrometry (ICP-MS), revealed 3 to 4-times greater Co uptake into CFs than 3T3 cells at 48 h.In vivo studies using echocardiography showed evidence of altered cardiac function in Co treated rats after 28 days exposure. Reduction of the percentage of fractional shortening (%FS), from 60.29±0.53%, to 54.01±0.90% n=6, p
Date of Award1 Oct 2017
LanguageEnglish
Awarding Institution
  • University Of Strathclyde
SupervisorSusan Currie (Supervisor) & (Supervisor)

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