Gel against adhesions
A group of researchers at the University of California, San Diego has developed a hydrogel that forms a barrier that prevents surrounding tissues from sticking to the surface of the heart after surgery. It has been successfully tested on rodents, as well as on pig hearts.
In rats, the hydrogel completely prevented the formation of adhesions. In an experiment with pig hearts, hydrogel treatment led to the formation of less dense adhesions, which were later easier to remove. In addition, the hydrogel did not seem to cause chronic inflammation.
Urgent need to solve the problem
Adhesions are the adhesion of organ tissues to the surrounding tissues. They are quite a serious problem in surgery. Every year in cardiac surgery, 20% of patients undergo repeated surgery to excise adhesions. Repeated operations are especially common among children – as the child's heart grows, additional interventions are required.
Adhesions form within the first 30 days after surgery and can complicate the postoperative period and increase the risk of death. In some cases, they can also interfere with the proper functioning of the heart and even completely eliminate the therapeutic effect of the operation. One of the authors of the article, Karen Christman, a professor of bioengineering at the University of California at San Diego, encountered this when her uncle's heart valve could not recover due to serious adhesions.
Currently, there are no FDA-approved remedies to prevent adhesions after heart surgery.
How it works
The new hydrogel, developed by bioengineers in Christman's laboratory, meets the needs of both patients and surgeons. It is easy to apply by spraying on the tissue in the operating wound. The gel binds to the heart muscle and turns into a soft, elastic coating that acts as a barrier against adhesions and at the same time does not prevent the heart from contracting. After 4-6 weeks, the gel decomposes independently and is removed from the body.
The biggest problem was to make sure that the hydrogel is firmly attached to the heart, but does not swell, as swelling can put dangerous pressure on the heart. To do this, Christman and her colleagues used the so-called chemical crosslinking, which consists in connecting molecules with a covalent bond. For stitching, it was decided to use catechol, a compound similar in structure to the substance that mussels use to adhere to stones.
Catechol contains levodopa, a protein that is also synthesized in the human body. A water-soluble polymer polyethylene glycol (PEG) was added to the gel base. The result is a hydrogel that adheres to the organ to which it is applied, but then creates a protective barrier for more than four weeks, after which it completely dissolves when adhesions are practically not formed.
Left: A rat's heart treated with hydrogel has almost no adhesions 2 weeks after surgery. On the right: the heart of a rat from the control group with dense adhesions.
Spray device
The researchers also developed a device for safely and accurately applying hydrogel to the heart in the area of surgery. The device in different chambers contains two main components of hydrogel. Each component is made of PEG with different reactive groups. One of the cells also contains a catechol. As you exit the device, all components are mixed to form a hydrogel.
Next steps
The authors are planning a large study on pigs, which will help clarify the dosage and study how the hydrogel reacts with suture material and drains. The goal of this future work is to conduct a clinical trial in one and a half to two years with the participation of children who have undergone cardiac surgery, and in a few more years to receive FDA approval.
According to the researchers, this technology can also be easily adapted to prevent adhesions on other organs.
Article by M.Fujita et al. Preventing post-surgical cardiac adhesions with a catechol-functionalized oxime hydrogel published in the journal Nature Communications.
Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru Based on UC San Diego: Bio-inspired hydrogel protects the heart from post-op adhesions.