Biodegradable thermo-responsive gel as a controlled release platform for intraocular drug delivery

By: Mirrah Almira - CMI Fellow
People over age 50 risk blindness caused by age-related macular degeneration (AMD). Current treatment for "wet AMD" involves frequent intraocular injections which are inconvenient for the patient and also costly. Determined to address this medical problem, a Pitt engineer and a physician have worked together to develop a new platform for controlled drug release which then can lessen the number of intraocular injections.

[Pittsburgh, February 12, 2015] According to American Academy of Ophthalmology, people over 50 risk having severe vision loss due to a disease called age-related macular degeneration (AMD). This is a disease that happens when the small portion of the retina, known as the macula, deteriorates. The macula, a light-sensitive tissue lining the back of the eye, is responsible for central vision and it enables a person to see fine details clearly. AMD can be either dry or wet; the latter is the rapidly progressing form of macular degeneration. Wet AMD can be characterized by the growth of abnormal blood vessels from the layer right underneath the retina. Those new vessels may leak fluid or blood and disrupt the central vision, which then leads to blindness.

In order to treat wet AMD, doctors usually give anti-VEGF which can suppress the work of Vascular Endothelial Growth Factor (VEGF). Anti-VEGF drugs, such as bevacizumab, will limit the growth of new blood vessels, thus decreasing vascular leakage. So far, intraocular injection of anti-VEGF has been a successful treatment for wet AMD. However, given that the half-life of this drug is short, the patient needs to have frequent intraocular injections of anti-VEGF during 2-3 years period of treatment. Such an inconvenient, risky, and costly procedure creates a burden to the patient and also to healthcare system in general.

A novel approach developed by a team of a physician and an engineer at the University of Pittsburgh incorporates the anti-VEGF in a biodegradable polymer that can turn into a gel once it reaches the vitreous of the eye (a clear jelly-like substance that fills the center of the eye). Before it is injected into the eye, the polymer will be in the form of a liquid. As soon as the polymer solution is within a body temperature environment, like in the vitreous, it will turn into a gel. This biodegradable thermo-responsive gel is suitable to be used as controlled release platform for intraocular drug delivery.

Using this new platform, the patient does not have to undergo frequent intraocular injections anymore. The gel will act as a biodegradable drug reservoir, releasing anti-VEGF in a timely manner. After certain duration, the gel will degrade to clear so that it will neither disturb the eyesight nor the composition of vitreous. This approach will not only bring convenience to the patient but also reduce the healthcare costs associated with the eye care visit and intraocular injection.

The talented people behind this invention are an engineer and a physician who have pioneered this medical breakthrough. They are:

The $25,000 funding from CMI in 2014 has supported the team in achieving their major targets including synthesis of the polymer, examining its thermo-responsiveness and degradation profile, and also testing its cytocompatibility. This biodegradable thermo-responsive gel has attracted attention from big pharmaceutical companies such as Roche ® and Novartis ® .

Future milestones that the team is eager to achieve are finishing the evaluation of this gel in the eyes of rodents and rabbits. The team is maintaining communication with the pharmaceutical company that is willing to commercialize this technology. (MA)