TU‐H‐CAMPUS‐TeP2‐05: Selective Protection of Normal Tissue by Cerium Oxide Nanoparticles During Radiation Therapy

Abstract

Purpose:Cerium oxide nanoparticles (CONPs) have unique pH dependent properties such that they act as a radical modulator. These properties may be used in radiation therapy (RT) to protect normal tissue. This work investigates the selective radioprotection of CONPs in‐vitro and potential for in‐situ delivery of CONPs in prostate cancer RT.Methods:i) Normal human umbilical vein endothelial cells (HUVEC) and human prostate cancer cells (PC‐3) were treated with 0 or 2 ng/mL CONPs (NP size: 5 nm). 2 Gy of 100 kVp radiation was delivered to the cells 4 hours after the CONP treatment. Cell viability was checked 48 hours later using MTS assays. ii) A prostate tumor was modeled as a 2‐cm diameter sphere. CONPs were proposed to be loaded in a hollow radiotherapy fiducial marker. The concentration profile for the CONPs within the tumor was modeled with a previously validated diffusion equation employed in other studies for nanoparticles 10 nm or less.Results:i) Without radiation, cell viability was above 90% when treated with 2 ng/mL CONPs for both HUVEC and PC‐3. After irradiation, a slightly higher viability was observed in HUVEC with CONPs than the ones without CONPs, and this effect was not observed in PC‐3. ii) Based on the calculations, 2 ng/mL of CONPs could be delivered to normal cells by diffusion with a 1 µg/mL initial concentration within two weeks.Conclusion:We conclude that CONPs can provide selective radioprotection. The delivery of needed concentrations of CONPs is feasible via in‐situ release from radiotherapy biomaterials (e.g. fiducials) loaded with the CONPs.