Diabetic retinopathy (DR) and retinal vein occlusions (RVO) are major causes of low vision and blindness. Although DR and RVO have different underlying pathophysiology, inner retinal hypoxia secondary to ischemia is central to these diseases. Existing therapeutic approaches like pharmacological injections, pan-retinal photocoagulation, focal laser, and surgery either do not address retinal hypoxia or do so at the cost of damaging retinal tissue. Moreover, even with intravitreal injections of anti-Vascular Endothelial Growth Factors, or laser, in approximately 50% of patients, vision does not improve. Our interdisciplinary team of biologists, physicists, engineers, and physicians from seven institutions has taken a novel approach towards treating ischemic retinal disease. In this proposal, using sophisticated biological experiments, bioinformatics, biophysics and advanced bio-microelectromechanical systems (bioMEMS) engineering, we propose an OXYGENATOR system to deliver highly controlled levels of oxygen that are precisely targeted to the ischemic retina (i.e., local oxygenation within a therapeutic window). We have made significant advances towards engineering of a wireless bioelectronic implant (OXYGENATOR) that can deliver safe amounts of oxygen to the retina in a controlled manner. The OXYGENATOR consists of two units;one wearable and the other implantable. The extraocular wearable components (single ergonomic, flexible, low profile design for day and night time use) provide the inductive (RF) link for power and data. The implantable components consist of electronics to receive power and data, electronic circuitry attached to MEMS electrodes inside oxygen permeable membrane bag for electrolysis, and a refillable saline reservoir to replenish the saline inside oxygen permeable bag. The OXYGENATOR functions when the external component transmits power and data under customized software control to the implanted electronics (note software can be personalized for each patient need). The implanted electronics receive, decode and deliver controlled electrical pulses to the MEMS electrodes to result in electrolysis of the saline inside the oxygen permeable membrane bag. The oxygen then diffuses in a controlled and directional manner out the bag to the retina while shielding the anterior eye structures such as the lens. Although only nanoliters of saline are used over months of electrolysis, a refillable saline reservoir to replenish the saline inside the permeable bag has been designed to lengthen the life of the OXYGENATOR to 5+ years. In this proposal, we share our results to date on this novel approach and outline our research program in 3 specific aims. Successful completion of these 3 aims in preclinical studies will enable us to attract follow-on industrial funding to embar on clinical studies.
The first aim i s to use short and long term tests to quantify the retinal oxyen requirements at the cellular and tissue level.
The second aim i s to engineer the OXYGENATOR to demonstrate long-term efficacy and maximize efficiency.
The third aim i s to study the spatiotemporal dynamics of oxygen production and diffusion by controlled electrolysis in the eye.
Diabetic retinopathy (DR) and retinal vein occlusions (RVO) are major causes of low vision and blindness. Although DR and RVO have different underlying pathophysiology, inner retinal hypoxia secondary to ischemia is central to these diseases. However, existing therapeutic approaches like pharmacological injections, pan- retinal photocoagulation, focal laser, and surgery do not adequately treat the underlying disease. Our interdisciplinary team of biologists, physicists, engineers, and physicians has made significant advances towards engineering of a wireless bioelectronic implant (OXYGENATOR) that can deliver safe amounts of oxygen to the retina in a controlled way for the treatment of ischemic retinal diseases.
|Murali, Karthik; Kashani, Amir H; Humayun, Mark S (2015) Whole vitreous humor dissection for vitreodynamic analysis. J Vis Exp :e52759|