Gross histology was performed with H&E (A, C, E and G) and anti-vimentin staining (B, D, F and H). Autologous rat aortic valves are shown in (A) and (B) confirming presence of cellular material and an intact ECM. Presence of cellular material and an intact ECM structure was observed in the non-decellularized guinea pig tissue prior to decellularization (C and D). Following decellularization there is complete absence of cellular material, however the ECM structure is grossly preserved (E and F). Recellularization with rat mesenchymal stem cells was performed and resulted in restoration of a confluent layer of mesenchymal stem cells lining the valvular tissue (G and H).