Valvular repair or transplantation, designed to restore the venous valve function of the legs, has been proposed as treatment in chronic venous insufficiency. Available grafts or surgeries have provided limited durability so far. Generating venous valve substitutes by means of tissue engineering could be a solution. We generated decellularized jugular ovine vein conduits containing valves (oVVC) after reseeding with ovine endothelial cells differentiated from peripheral blood-derived endothelial cells (oPBEC), cultivated in vitro corresponding to the circulatory situation in the lower leg at rest and under exertion. oVVC were decellularized by detergent treatment. GFP-labeled oPBEC were seeded onto the luminal side of the decellularized oVVC and cultivated under static-rotational conditions for 6 h (group I) and 12 h (group II), respectively. Reseeded matrices of group I were exposed to continuous low flow conditions (“leg at rest”). The tissues of group II were exposed to a gradually increasing flow (“leg under effort”). After 5 days, the grafts of group I revealed a uniform luminal endothelial cell coverage of the examined areas of the venous walls and adjacent venous valve leaflets. In group II, the cell coverage on luminal areas of the venous wall parts was found to be nearly complete. The endothelial cell coverage of adjacent venous valve leaflets was revealed to be less dense and confluent. Endothelial cells cultured on acellular vein tissues of both groups were distinctly orientated uniformly in the flow direction, clearly creating a stable and flow-orientated layer. Thus, an endothelium could successfully be reestablished on the luminal surface of a decellularized venous valve by seeding peripheral blood endothelial cells and culturing under different conditions.

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Background: Autologous pericardium is widely used for the repair of different sized cardiovascular defects. However, its use is limited especially in redo cardiac surgery. We developed an engineered tissue based on decellularized pericardium reseeded with blood-derived endothelial cells. Materials and Methods: Decellularization of ovine pericardium was performed using detergent treatment. Ovine outgrowth blood-derived and green fluorescent protein–labeled endothelial cells were used to reseed the decellularized ovine pericardium on the mesothelial side. The cell adhesion was assessed using fluorescent microscopy up to 15 days of in vitro cultivation. The mechanical properties of the pericardium were evaluated using suturability, burst pressure, and suture retention strength tests. Results: After decellularization the pericardial sheets appeared cell-free and repopulation using ovine blood-derived endothelial cells was successful by forming a robust monolayer. Detergent treatment did not affect the extracellular matrix. The thickness of decellularized tissue was similar to native ovine pericardium (285.3 ± 28.2 µm, respective 276.9 ± 23.8 µm, p = 0.48). Decellularized patch showed similar suturability comparable to the native ovine pericardium. Resulted burst pressure was not significantly different (native/decellularized: 312.5 ± 13.6/304.2 ± 16, p = 0.35). The suture retention strength of native pericardium was 638.33 ± 90.2 gr and comparable to decellularized tissue (622.2 ± 89.9 gr, p = 0.76). No differences were observed concerning elongation of native and decellularized pericardium (8.33 ± 1.5 and 8.5 ± 0.84 mm, respectively; p = 0.82). Conclusion: Mesothelial surface of decellularized ovine pericardium is suitable for reseeding with ovine blood-derived endothelial cells. The mechanical properties of detergent-treated pericardium were comparable to native tissue.