Oxygen Monitor to Study Vascularization of Medical Devices
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MRS Advances © 2020 Materials Research Society DOI: 10.1557/adv.2020.97
Oxygen Monitor to Study Vascularization of Medical Devices Avid Najdahmadi1*, Rachel Gurlin2*, Mellonie Zhang2, Jonathan RT Lakey2,3, Elliot Botvinick 1,2,3 1
Department of Materials Science and Engineering, University of California Irvine, Irvine, USA
2
Department of Biomedical Engineering, University of California Irvine, Irvine, USA
3
Department of Surgery, University of California Irvine, Irvine, USA
* These authors contributed equally
Abstract:
Prevascularized medical devices can improve cell therapy. Such devices may replace whole organ transplantation with hosting only the necessary therapeutic cells. We have developed a noninvasive optical technology to study the vascularization into such medical devices. In our technique, oxygen partial pressure within a device is monitored by Oxygen Sensitive Tubes (OSTs), comprising oxygen permeable silicone tubing with inner luminal surfaces coated by an oxygen-sensitive porphyrin dye. OSTs were placed within a PDMS device and transplanted into the subcutaneous space of athymic nude mice. An optical probe placed over the skin excites the OSTs with a pulse of light and detects the luminescent lifetime of emitted light, which is uniquely related to oxygen partial pressure. Furthermore, we developed a Dynamic Inhalation Gas Test (DIGT) to determine the oxygen transport rate between the microvasculature and the device. DIGT works by monitoring oxygen partial pressure in a device following a step change in inhaled-gas oxygen content. We report DIGT oxygen dynamics measured intermittently over eight weeks. Our study shows DIGT dynamics are unique to each implant, supporting the important role of the host tissue response in the availability of oxygen over time.
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INTRODUCTION: Cell transplantation approaches have been emerging as an alternative to whole organ transplantation for replacement of dysfunctional organs [1]. For example, in the case of type 1 diabetes, insulin-producing cells within pancreatic islets are destroyed by the immune system, which results in unchecked glycemic control [2]. Currently, the most common method of treatment is daily injection of insulin, which is not a cure, and can cause secondary microvascular conditions [3]. One promising approach as an alternative to whole pancreas transplantation is isolation and transplantation of insulin-producing pancreatic islets [4]. However, the main limitation of such an approach is the limited supply of human donor cells, which necessitates new approaches such as xenotransplantation, ultimately resulting in rejection of the transplanted islets by the recipient’s immune system, and therefore necessitating lifelong immunosuppression drug therapy[5]. Various tissue engineering techniques have been used to address thi
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