Engineers from the Massachusetts Institute of Technology have created a flexible drug patch that is applied directly to the heart after a heart attack, helping to speed up the recovery and regeneration of heart tissue. The device is capable of delivering several types of drugs at once, and each of them can be released according to a predetermined schedule. In experiments on rats, researchers found that using the patch reduced the amount of damaged heart tissue by half and markedly improved heart function. According to the scientists, once approved for clinical use, this type of patch could significantly improve the effectiveness of restoring cardiac function in people who have had a heart attack.
After a heart attack, many patients undergo bypass surgery, which improves blood flow to the heart but does not help repair damaged tissue. As part of the study, scientists decided to develop a special patch that could be attached to the heart directly during surgery. The researchers hoped that such a patch would be able to gradually release drugs, supporting the healing process over a long period of time.
To implement this idea, scientists decided to use previously created microparticles for drug delivery. These particles are tiny capsules shaped like miniature coffee cups with lids made from PLGA polymer. A medicinal substance can be placed inside such capsules and sealed hermetically. By changing the molecular weight of the polymer from which the caps are made, researchers can control the rate at which they degrade. This allows you to precisely set the moment when the contents of each capsule will be released. As part of this experiment, three types of particles were created that were destroyed at different times – approximately on the 1st-3rd, 7-9th and 12-14th days after implantation.
Thus, it was possible to plan a three-stage therapy, in which each substance plays its role in restoring the heart. The first group of particles secretes neuregulin-1, a growth factor that protects cells from death. The second releases VEGF, which stimulates the formation of new blood vessels around the heart. The latter contains the drug GW788388, which prevents the formation of scars that occur after a heart attack.
The scientists embedded rows of microparticles into thin sheets of a strong but flexible hydrogel with the consistency of contact lenses. This material consists of alginate and PEGDA – biocompatible polymers that are gradually destroyed in the body. For the experiment, the researchers made miniature patches with a diameter of only a few millimeters. The resulting patches were tested on spherical samples of cardiac tissue created from cardiomyocytes derived from induced pluripotent stem cells. These spheres also included endothelial cells and fibroblasts of the human heart, important elements of cardiac structure. To simulate post-heart attack conditions, the samples were exposed to low levels of oxygen and then patched. The results showed that the device stimulates blood vessel growth, increases cell survival and reduces the development of fibrosis.
When tested on rats undergoing an artificially induced heart attack, the patch also showed significant effects: compared with no treatment or the usual administration of the same drugs, the animals’ survival increased by 33%, the amount of tissue damage was reduced by half, and cardiac output was markedly increased. An important note that the researchers made was that the patches gradually dissolve over time, turning over the course of a year into a very thin layer that does not affect the mechanical functioning of the heart.