Congenital heart disease affects approximately 40,000 newborns each year in the U.S. Valve and conduit replacements are needed for absent pulmonary valve, aortic stenosis (Konno procedure, Ross procedure), double outlet right ventricle (Rastelli operation), extracardiac conduit (Fontan operation), pulmonary valve replacement (Tetralogy of Fallot). Materials in current use include homograft blood vessels; glutaraldehyde treated bovine jugular veins (BJV, Contegra), polytetrafluorethylene (PTFE), and woven or knitted Dacron tubes. The limitations of these materials involve to varying degrees their thrombogenicity, durability, susceptibility to infection, and lack of growth potential. These materials also have varying degrees of stiffness and flexibility, which present technical challenges for surgeons, particularly in neonates and infants where size constraints and limited space in the mediastinum combine with the relatively thin immature native vascular tissues to create tissue-materials mechanical mismatches, which can compromise the ability to achieve a successful surgical repair. Current clinical experience indicates that young age, in particular, is an important risk factor for shortened intervention free survival in patients requiring these conduits as part of their initial surgical repair. The goal of creating a conduit that will overcome these limitations has not been achieved. We propose to develop a commercializable prototype and test the regenerative potential of decellularized and pentagalloyl glucose (PGG) crosslinked novel BJV valved conduit device (TxGuard) that would repopulate with host cells and slowly regenerate and grow with the patient without unwanted inflammation and degeneration in contrast to the existing devices.
Our specific aims for STTR Phase I are:
Specific Aim 1 : Scale-up our laboratory-based decellularization and PGG crosslinking method to a batch manufacturing process for TxGuard from a verified supplier with certification in ISO 13485. This includes dissemination of treatment protocol to the manufacturing partner to standardize manufacturing process for obtaining a consistent product.
Specific Aim 2 : Compare TxGuard that is made under ISO 13485 conditions with a commercially available device (Contegra) for material properties (suture pull out test, biaxial mechanical testing, and creep), cytotoxicity, and hemocompatibility assessment (ISO 10993 testing).
Specific Aim 3 : Test TxGuard for in vivo biocompatibility and functional assessment. This will include a) 90-day subdermal implantation in juvenile rats to assess calcification resistance and b) implantation in sheep as a pulmonary-valved conduit for three months to assess safety, function, biocompatibility, and cellularization by the host animal in a circulatory environment.
Congenital heart disease affects approximately 40,000 newborns each year in the U.S. Valve and conduit replacements are needed for absent pulmonary valve, aortic stenosis (Konno procedure, Ross procedure), double outlet right ventricle (Rastelli operation), extracardiac conduit (Fontan operation), pulmonary valve replacement (Tetralogy of Fallot). Current replacement materials are suboptimal with high failure rate requiring reoperations. This research proposal is designed to develop a new pulmonary-valved conduit (TxGuard) that resists early degeneration and allows regeneration with host cells so that the device would grow with the pediatric patient.
