Quantitative methods for in vitro and in vivo characterization of cell and tissue metabolism

Abstract

Characterization of cell and tissue metabolism is critical for the diagnosis and tracking of disease and the development and implementation of new treatments. Metrics for metabolism span tissue oxygen and pH levels and cellular thermal output. This need is present in research and clinical applications both of which are underserved by existing technologies. This thesis presents the development of three distinct technologies: an implantable oxygen sensor for clinical monitoring of tumor oxygen content in cervical cancer, an in vitro screening platform for monitoring thermal output in a multi-well plate format, and an implantable pH sensor. This thesis presents a silicone-based quantitative oxygen sensor for clinical use in cervical cancer. Oxygen measurements are made using MRI, which is already part of the clinical workflow for this patient population. This sensor is Institutional Review Board approved for a ten-patient clinical trial in women with pathologically-confirmed cases of cervical cancer. Hypoxia has been linked to poor clinical outcomes, including lower survival rates. Hypoxia-induced resistance to radiotherapy presents an intriguing clinical opportunity because boosting the radiation dose can overcome the radiotherapy resistance present in hypoxic tumor subvolumes. Existing oxygen-sensing methods are not sufficient to enable customization of radiation therapy dose delivery, necessitating the development of new sensing technologies. The presented work covers the validation and use of a system to measure thermal output from biological and chemical systems. Plate-based screening platforms offer significant advantages over existing alternatives that require substantial deviations from standard experimental protocols. Applications of this platform include screening of new treatments in cell culture and determining the extent of chemical reactions. This thesis also presents the development of an implantable polymeric pH sensor. It is hydrogel based and provides quantitative measurements of tissue pH levels using MRI. Measurements of tissue pH are of interest in a number of clinical applications including chemotherapy selection and monitoring tumor response. The oxygen and pH sensors can be used simultaneously to provide parallel measurements of both metrics of metabolism.