Biological Tissue Alternatives for Africa

Africa is home to 33 million people living with rheumatic heart disease (RHD). As RHD is a disease of the young, valve replacements are required by young patients, many without access to anti coagulation clinics. As many as 2 million children with congenital heart disease require surgery, many with a tissue patch as part of the repair.

Homografts remains the gold standard for RVOT repairs in children and its role as a valve or valved conduit is well established in the aorta position. Availability remains a problem. The homograft bank at the University of the Free State (UFS) have harvested more than 3000 homografts and provided cryopreserved homografts for more than 1600 implants. We have shown that extending harvest times beyond 24 hours had no adverse impact on homograft survival in 253 children who received a RVOT implant between 1990 and 2013. In in vitro and in vivo ovine experimental models, harvest times up to 72 hours had no adverse affect on tissue integrity and valve performance after 180 day implants. We thus recommend extending the harvest times up to 48 hours allowing for cadaver donor programs to attenuate homograft shortages as a valve alternative for Africa.

As tissue degeneration and calcification is linked to immune processes, an SDS and detergent combination proprietary process for decellularisation and sterilization for both homografts and bovine pericardium has been developed and evaluated in vitro and in vivo.

SDS combination decellularisation processes are associated with a non significant tissue strength reduction, a pronounced reduction in GAG’s and triglyceride content and an insignificant reduction in alpha Gal. Decellularisation is associated with marked reduction in calcification compared to any group using gluteraldehyde in rat studies.

Tissue engineered biological alternatives with reduced degeneration in the young remains an important field of research and development.