DNA Damage in Human T cells by Human Prosthetic Ion Shedding and Debris Particles
Authors:Lucy Wei Li, Sonia Ramirez
Mentor:Steve Alas, Associate Professor of Biological Sciences, California State Polytechnic University Pomona
Titanium and stainless steel have been used as prosthetic materials worldwide for many years. However, there has been an increased in revision surgeries to replace failed implants due to osteolysis and prosthetic loosening. This is typically caused by inflammation due to debris and nanoparticles released from the prosthetic. Studies also suggest that nanoparticles result in DNA double & single strand breaks. However, the mechanisms involved in nanoparticle-induced genotoxicity and carcinogenicity are poorly defined. In this study, CEM cells (human T cell line) were cultured and exposed to ion solutions from corrosion experiments performed on novel experimental prosthetic alloys developed by researchers in the Department of Chemical & Materials Engineering at Cal Poly Pomona. CEM cells were treated with different ratios of ions and growth media. Concentration curves demonstrated that a mixture of 80% ion solution and 20% growth media was the highest ion concentration the cells could tolerate, without the saline solvent inducing high levels of apoptosis. The treatment times were 24, 48, and 72 hours. After treatment, CEM cells were analyzed for apoptosis using propidium iodide staining. Cells were also examined for DNA damage using the Comet Assay, which determines the amount of DNA single- and double-strand breaks by gel electrophoresis, and Comet Score software. Results showed that prosthetic ions, derived from the Ti-6Al-4V alloy, do not induce apoptosis after 24, 48 or 72 hours. Importantly, ion shedding from the prosthetic alloy (Ti-6Al-4V) does induce DNA single- and double-strand breaks after 6 hours. By 24 hours, the cells showed the ability to repair DNA damage from the ion treatment. Future experiments will focus on apoptosis and DNA strand breaks caused by ion solutions from ten different prosthetic alloys. The results will determine which prototype alloy produces less DNA damage and, hence, makes for a better biomaterial for implant use.