Decellularized human valve allografts

Background. Variable performance of allograft tissues in children and some adults may be linked to an immune response and could be mitigated by reducing implant antigenicity. Methods. As endothelial and fibroblast cells are the likely source of valve antigenicity, human (CryoValve SG) and sheep pulmonary valves were decellularized using the SynerGraft treatment process. Treated valves were evaluated in vitro using histochemical, biomechanical, and hydrodynamic methods, and compared with standard cryopreserved valves. Four SynerGraft-treated and two cryopreserved sheep pulmonary valves were implanted as root replacements in the right ventricular outflow tract of growing sheep and monitored echocardiographically and histologically at 3 and 6 months. CryoValve SG human pulmonary valves were implanted in 36 patients. Results. SynerGraft treatment reduced tissue antigen expression but did not alter human valve biomechanics or strength. Decellularized sheep allograft valves were functional during the implantation period, and, they became progressively recellularized with recipient cells. In humans, CryoValve SG pulmonary valves did not provoke a panel reactive antibody response. Conclusions. SynerGraft decellularization leaves the physical properties of valves unaltered and substantially diminishes antigen content. Reduction in implant cellularity enables host recellularization of the matrix, which should favorably impact long-term graft durability. (C) 2001 by The Society of Thoracic Surgeons.