Summary. Currently, there are no approved and available products to prevent postsurgical cardiac adhesions and hence no standard of care. This is a large unmet need since there are >500,000 open-heart surgeries/year (projected to grow to >850,000 by 2030) and >100,000 of these are reoperations and ~30,000 are on children with congenital heart defects. Reoperations in cardiac surgery have increased surgical risks due to cardiac adhesions, which increase the difficulty of sternal reentry, hinder visibility of mediastinal tissues, and increase potential injury to cardiovascular tissues. Injuries occurring to adhesion removal triples the mortality of reoperation patients, increase operation time and hospital costs. This is especially relevant for pediatric patients with congenital heart defects who will experience multiple surgeries over their lifetime. Cardiac adhesions have also become a common problem in adults who experience multiple surgeries to repair or replace valves or to undergo coronary revascularization procedures. Two main approaches exist for reducing or attempting to prevent cardiac adhesions: pharmacological therapy and physical barriers. Drugs that prevent or reverse adhesion processes disrupt biochemical pathways of inflammation and fibrin deposition. Unfortunately, these processes are also vital for wound healing. Achieving adequate drug concentration at the site of action is also challenging due to fluid drains. A more viable approach is the use of a physical barrier to prevent fusion of the heart to surrounding tissues. The barriers can be either preformed membranes or injectable hydrogels (fast gelling liquids). Preformed anti-adhesive materials need to be cut before application to the tissue, and must be sutured/packed into place to prevent slippage. Injectable hydrogels allow the freedom of applying material where needed with spraying. The precursor components are capable of quickly reacting, forming a protective gel on the surface of the tissue. While a variety of different materials have been investigated in animals and humans, no materials, to date, have been capable of preventing adhesion formation post-cardiac surgery. Herein, we propose a new approach to prevent postsurgical cardiac adhesions using TissueShield™, which is composed of a rapidly forming poly(ethylene glycol) (PEG) hydrogel that is cross-linked by oxime bonds and includes a tissue binding moiety to ensure the product remains adhered to the heart. Our approach is a 3-polymer system that can be easily sprayed directly onto the heart forming a robust anti-adhesion layer within seconds. This system has already been optimized to control the degree of swelling and degradation time to prevent adhesions and not interfere with cardiac function in rat cardiac adhesions models and an initial small pilot study in a porcine model. No product has been shown to have our features (tissue binder, low swelling, and lifespan). The objective herein is to optimize the delivery volume and evaluate preliminary efficacy and safety of TissueShield™ of in a large animal cardiac adhesions model. Follow up powered study will compare this volume with abdominal products. This will be the first sprayable anti-adhesions product designed specifically for preventing cardiac adhesions.

Project Narrative Currently, there is no approved and available product to prevent postsurgical cardiac adhesions, and hence no standard of care for prevention. These cardiac adhesions increase the morbidity and mortality of hundreds of thousands of cardiac reoperation patients due to complications associated with adhesion removal. This proposal uses a preclinical animal model of cardiac adhesions to investigate a novel adhesion barrier with unique properties that has been specifically designed for the heart and to prevent postsurgical cardiac adhesions.