Decellularized heterografts versus cryopreserved homografts: experimental study in sheep model.

OBJECTIVES: The aim of this study is to assess the biological behaviour of porcine decellularized heterografts (Desc group) compared with cryopreserved homografts (Crio group) implanted in juvenile sheep. METHODS: Decellularized porcine pulmonary heterografts were implanted in five animals and cryopreserved pulmonary homografts in another five. The animals were followed-up for a mean of 280 +/- 14 days. The valve diameter was measured by echocardiography, which was performed at the 30th postoperative day, and before the explantation. The valves were also assessed macroscopically. Histological evaluation was performed using H.E., Gomori and Weigert staining. Immunohistochemistry specified different cell types (Factor VIII, CD3, Vimentin and CD68). Calcium quantity was analyzed using atomic absortion spectometry. RESULTS: There was one death in the Desc group due to endocarditis. The valves of Crio group showed decrease in the cellularity whereas the valves of Desc group showed matrix repopulation with endothelial and interstitial cells. Loss of collagen density and disarrangement of the normal fiber architecture was observed in Crio group. Calcium content demonstrated higher levels on the cusps and conduits in Crio group comparatively with Desc group. (P=0.016). The mean valvular diameter at the explantation was significantly increased (P=0.025) in the Desc group. CONCLUSIONS: Decellularized heterografts had a different biological behaviour when compared to cryopreserved homografts and become repopulated by cells with fibroblasts and endothelial cells characteristics. The matrix was preserved and some regenerative potential was present.

Análise do comportamento biológico de heteroenxertos descelularizados e homoenxertos criopreservados: estudo em ovinos / Decellularized heterografts versus cryopreserved homografts: experimental study in sheep model

OBJETIVO: Este estudo avalia o comportamento biológico dos heteroenxertos porcinos descelularizados (Grupo Desc) comparados com os homoenxertos criopreservados (Grupo Crio) implantados em carneiros jovens. MÉTODOS: Foram implantados em cinco animais heteroenxertos pulmonares porcinos descelularizados e em outros cinco, homoenxertos pulmonares criopreservados. Os animais apresentaram seguimento médio de 280 ± 14 dias. O diâmetro valvar foi medido por ecocardiografia, a qual foi realizada no 30º pós-operatório e antes do explante. As valvas foram também avaliadas macroscopicamente. A avaliação histológica foi realizada utilizando-se coloração de H.E., Gomori e Weigert e imunohistoquímica (Fator VIII, CD3, Vimentina e CD68). A quantificação de cálcio foi realizada utilizando-se espectrometria de absorção atômica. RESULTADOS: Houve um óbito no Grupo Desc por endocardite. As valvas do Grupo Crio apresentaram decréscimo na celularidade, enquanto que as valvas do Grupo Desc demonstraram repovoamento da matriz com células endoteliais e intersticiais. No grupo Crio, observou-se perda na densidade e desarranjo da arquitetura das fibras colágenas. A espectrometria de absorção atômica demonstrou maior calcificação no conduto e nas cúspides dos enxertos criopreservados quando comparados aos descelularizados (P=0,016). O diâmetro médio valvar no explante foi significantemente maior no Grupo Desc (P=0,025). CONCLUSÃO: Heteroenxertos descelularizados apresentam um comportamento biológico diferente quando comparados aos homoenxertos criopreservados, tornando-se repovoados por células com características de fibroblastos e células endoteliais. A matriz permaneceu bem preservada, o que possibilitou um processo de regeneração celular.

OBJECTIVES: The aim of this study is to assess the biological behaviour of porcine decellularized heterografts (Desc group) compared with cryopreserved homografts (Crio group) implanted in juvenile sheep. METHODS: Decellularized porcine pulmonary heterografts were implanted in five animals and cryopreserved pulmonary homografts in another five. The animals were followed-up for a mean of 280 ± 14 days. The valve diameter was measured by echocardiography, which was performed at the 30th postoperative day, and before the explantation. The valves were also assessed macroscopically. Histological evaluation was performed using H.E., Gomori and Weigert staining. Immunohistochemistry specified different cell types (Factor VIII, CD3, Vimentin and CD68). Calcium quantity was analyzed using atomic absortion spectometry. RESULTS: There was one death in the Desc group due to endocarditis. The valves of Crio group showed decrease in the cellularity whereas the valves of Desc group showed matrix repopulation with endothelial and interstitial cells. Loss of collagen density and disarrangement of the normal fiber architecture was observed in Crio group. Calcium content demonstrated higher levels on the cusps and conduits in Crio group comparatively with Desc group. (P=0.016). The mean valvular diameter at the explantation was significantly increased (P=0.025) in the Desc group. CONCLUSIONS: Decellularized heterografts had a different biological behaviour when compared to cryopreserved homografts and become repopulated by cells with fibroblasts and endothelial cells characteristics. The matrix was preserved and some regenerative potential was present