Eduardo Discher Vieira

Operação de Ross com homoenxertos valvares decelularizados: resultados de médio prazo

Objective: To evaluate the medium-term results (4 years) of decelularized allografts during Ross Operation. Method: From January 2003 to February 2007, 68 patients underwent Ross Operation with decelularized allografts. Forty eight were male and the mean age was 30.3±11.2 years. Decelularization was done with deoxicolic acid (DOA) in 35 cases and with sodium dodecylsulfate (SDS) in 33. For comparison of the gradients, 68 patients with cryopreserved allografts and matched for age were selected. All patients had a control echo before hospital discharge and annually thereafter. In addition, eight patients had MRI studies. In two patients, samples of the conduit wall were analyzed by histological analysis. Results: There was one (1.4%) early death. In the late follow-up, there were two reoperations for endocarditis and one late death. The early gradients varied between 4 - 29 mmHg (m= 10.3± 5.5mmHg) and exhibited an increase to 16.5±12.2 mmHg (min= 4, max= 45) at 24 months postoperatively. There were no significant differences when compared to the cryopreserved group. There was, however, a tendency towards lesser gradients in the SDS decelularized group after 12 months. Histological analysis revealed partial reendothelization and progressive repopulation of the tunica media media wall with autogenous cells. There was no progressive pulmonary insufficiency. The MRI results showed a lesser tendency to shrinkage in the decelularized conduits.

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.

Evaluation of the biological behavior of decellularized pulmonary homografts: an experimental sheep model

INTRODUCTION The cryopreserved homograft is a good valve substitute due attributes like excellent hemodynamics, low incidence of thromboembolic events, infection resistance and good mid-term durability. However, progressive homograft degeneration and fibrocalcification may occur, particularly in the childhood and young adults. Their antigenicity triggers an immunological reaction that plays an important role in their degeneration and failure. The decellularization process was proposed to decrease this antigenicity. By the action of detergents and enzymes, this process removes all cellular components from the homograft matrix, diminishing immunogenicity and probably delaying its degeneration. OBJECTIVE The objective of this experimental and descriptive study is to evaluate the biological and functional behavior of decellularized pulmonary homografts (Decell-H), treated by a sodium dodecil sulfate solution (0.1%), developed in our University (Pontifícia Universidade Católica do Paraná). For the characterization of Decell-H performance, parameters like recellularization, calcification, and echocardiographic data will be analyzed. METHODS Eight juvenile sheep were submitted to the implantation of the Decell-H sutured into orthotopic position, through a left thoracotomy and with cardiopulmonary bypass support. They were followed-up clinically and by periodical echocardiograms until the explantation, which were performed in different time for every two sheep: seven, 30, 90 and 180 postoperative days. For histological analysis we used Hematoxilin-eosin, Movat and Alizarin-Red staining. RESULTS The sheep reached their follow-up period in a good clinical state. There was no valve regurgitation or stenonis by the echocardiogram. The animals submitted to the explantation in 90 and 180 days had a significant somatic growth and these Decell-H(s) had a diameter increase, without central valve insufficiency. Histologically, all homografts preserved their extra-cellular matrix organization and were progressively recellularized, without calcification. CONCLUSION In this experimental model, the Decell-H behaved as an excellent valve substitute.

Experimental study with deccelularized porcine heterografts: the prosthesis of the future

OBJETIVO: Avaliar, comparativamente, o comportamento de homoenxertos valvares criopreservados e de heteroenxertos descelularizados implantados na via de saida do ventriculo direito de carneiros jovens, assim como relatar a experiencia clinica inicial com homoenxertos descelularizados em pacientes submetidos a operacao de Ross. METODO: No grupo A, foram implantados quatro homoenxertos pulmonares criopreservados e no Grupo B, quatro heteroenxertos porcinos valvares descelularizados com acido deoxicolico. Em cada grupo, dois animais foram sacrificados no 3o mes e dois no 5o mes de pos-operatorio. As pecas foram avaliadas macroscopicamente e por radiografias, alem de exame microscopico com coloracoes HE, Tricromico de Mallory e Sirius Red. A experiencia clinica com quatro pacientes submetidos a operacao de Ross com emprego de homoenxertos valvares descelularizados e relatada. RESULTADOS: Todos os animais sobreviveram. Os ecocardiogramas demonstraram boa funcao valvar nos dois grupos. Embora as cuspides valvares em ambos os grupos tivessem aspecto macroscopico normal, a mensuracao de calcio e o estudo radiologico demonstraram inicio de calcificacao focal nos homoenxertos criopreservados, mas nao nos heteroenxertos descelularizados. Esses achados foram confirmados por exames microscopicos. Os homoenxertos criopreservados demonstraram perda de sua celularidade, enquanto que os heteroenxertos descelularizados demonstraram repopulacao progressiva da matriz colagena com fibroblastos, assim como reendotelizacao. Os quatro pacientes operados tiveram evolucao pos-operatoria imediata satisfatoria, com funcao normal dos homoenxertos. CONCLUSOES: Heteroenxertos valvares descelularizados foram progressivamente repopulados por celulas autogenas e exibiram minima tendencia a calcificacao no modelo estudado. Esses resultados sugerem que homoenxertos descelularizados possam ter alguma capacidade regenerativa e com isso ter durabilidade superior aos homoenxertos criopreservados convencionais.

Decellularization as an anticalcification method in stentless bovine pericardium valve prosthesis: a study in sheep

OBJECTIVE The objective was to analyze the decellularization process with SDS in glutaraldehyde-preserved bovine pericardium as an anticalcification method in a circulatory sheep model. METHODS The valved tubs were implanted in pulmonary artery position in sheep by 180 days. The animals were divided in two groups of 8 animals: control group--glutaraldehyde-preserved bovine pericardium and the study group--decellularized bovine pericardium with 0,1% SDS and glutaraldehyde-preserved. After explantation the tubs were analized by x-ray macroscopy, hematoxilin-eosin, alizarin-red and Russel-Movatz pentacromic histology. The calcium content was measured by flame atomic absorption spectrometry. RESULTS There was no early mortality, but two animals in each group died during the study. All cusps in the control group were severely calcified and in some points in the conduits, while the decellularized group did not show macroscopic calcification. Data were proved by x-ray and histologycal exams. The matrix was preserved in histologycal analysis in decellularized group, without gross calcification. The wall conduits calcium content was 35,25 ± 42,13 µg/mg in the control group versus 15,75 ± 10,44 µg/mg in the decellularized one: in the cusps was 264,4 ± 126,16 µg/mg in control group versus 94,29 ± 27,05 µg/mg in decellularized group (P = 0,009). CONCLUSION The decellularization with 0.1% SDS was effective as an anticalcification method in bovine pericardial grafts implanted in a sheep circulatory model for 180 days.

Effect of SDS-based decelullarization in the prevention of calcification in glutaraldehyde-preserved bovine pericardium: study in rats

OBJECTIVE The aim of study was to investigate the SDS-based decellularization process as an anticalcification method in glutaraldehyde-preserved bovine pericardium in subcutaneous rat model. METHODS Pericardium samples with 0.5 cm² area were divide in four groups: group GDA: 0.5% glutaraldehyde-preserved pericardium (GDA); group GDA-GL: GDA + 0.2% glutamic acid (GL); group D-GDA: decellularized (D) pericardium with 0.1% SDS + GDA and group D-GDA-GL: decellularized pericardium + GDA + 0.2% glutamic acid. After this samples were implanted in 18 rats in subcutaneous position till 90 days. Each animal received samples of the four groups. The explants were performed at 45 and 90 days. The explants were subjected to histology in glass slides stained with hematoxilin-eosin and alizarin red, morphometry evaluation and the calcium content was measured by flame atomic absorption spectrometry. RESULTS The inflammatory infiltrate was the same in all groups, however more intense in GDA and GDA-GL groups in 45 days, increasing at 90 days. The calcium contents for 45 days were: 32.52 ± 3.19 µg/mg in GDA group; 22.12 ± 3.87 µg/ mg in GDA-GL group; 1.06 ± 0.38 µg/mg in D-GDA group and 3.99 ± 5.78 µg/mg in D-GDA-GL (P< 0.001). For 90 days were 65.91 ± 24.67 µg/mg in GDA group; 38.37 ± 13.79 µg/mg in GDA-GL group; 1.24 ± 0.99 µg/mg in D-GDA group and 30.54 ± 8.21 µg/mg in D-GDA-GL (P< 0.001). Only D-GDA did not show increase rates of calcium at 45 to 90 days (P=0.314). CONCLUSION SDS-based decellularization process reduced the inflammatory intensity and calcification in bovine pericardium in subcutaneous rat model for 90 days.Objective: The aim of this study was to investigate the SDS-based decellularization process as an anticalcification method in glutaraldehyde-preserved bovine pericardium in subcutaneous rat model. Methods: Pericardium samples with 0.5 cm 2 area and divided into four groups: GDA group: 0.5% glutaraldehydepreserved pericardium (GDA); GDA-GL group: GDA + 0.2% glutamic acid (GL); D-GDA group: decellularized (D) pericardium with 0.1% SDS + GDA, and D-GDA-GL group: decellularized pericardium + GDA + 0.2% glutamic acid. Afterwards these samples were implanted in 18 rats in subcutaneous position up to 90 days. Each animal received samples of the four groups. The explants were performed at 45 and 90 days. The explants were subjected to histology in glass slides stained with hematoxilin-eosin and alizarin red, morphometry evaluation and the calcium content was measured by flame atomic absorption spectrometry. Results: The standard of inflammatory infiltrate was the same in all groups, however more intense in GDA and GDAGL groups in 45 days, increasing at 90 days. The calcium contents for 45 days were: 32.52 ± 3.19 µg/mg in GDA group; 22.12 ± 3.87 µg/mg in GDA-GL group; 1.06 ± 0.38 µg/mg in D-GDA group and 3.99 ± 5.78 µg/mg in D-GDA-GL (P< 0.001). For 90 days were 65.91 ± 24.67 µg/mg in GDA group; 38.37 ± 13.79 µg/mg in GDA-GL group; 1.24 ± 0.99 µg/mg in D-GDA group and 30.54 ± 8.21 µg/mg in D-GDA-GL (P< 0.001). Only D-GDA did not show increase rates of calcium at 45 to 90 days (P=0.314). Conclusion: SDS-based decellularization process reduced the inflammatory intensity and calcification in bovine pericardium in subcutaneous rat model for 90 days.