Publications (2)7.84 Total impact
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Article: Variation in tissue outcome of ovine and human engineered heart valve constructs: relevance for tissue engineering.
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ABSTRACT: Clinical application of tissue engineered heart valves requires precise control of the tissue culture process to predict tissue composition and mechanical properties prior to implantation, and to understand the variation in tissue outcome. To this end we investigated cellular phenotype and tissue properties of ovine (n = 8) and human (n = 7) tissue engineered heart valve constructs to quantify variations in tissue outcome within species, study the differences between species and determine possible indicators of tissue outcome. Tissue constructs consisted of polyglycolic acid/poly-4-hydroxybutyrate scaffolds, seeded with myofibroblasts obtained from the jugular vein (sheep) or the saphenous vein (from humans undergoing cardiac surgery) and cultured under static conditions. Prior to seeding, protein expression of α-smooth muscle actin, vimentin, nonmuscle myosin heavy chain and heat shock protein 47 were determined to identify differences at an early stage of the tissue engineering process. After 4 weeks of culture, tissue composition and mechanical properties were quantified as indicators of tissue outcome. After 4 weeks of tissue culture, tissue properties of all ovine constructs were comparable, while there was a larger variation in the properties of the human constructs, especially the elastic modulus and collagen content. In addition, ovine constructs differed in composition from the human constructs. An increased number of α-smooth muscle actin-positive cells before seeding was correlated with the collagen content in the engineered heart valve constructs. Moreover, tissue stiffness increased with increasing collagen content. The results suggest that the culture process of ovine tissues can be controlled, whereas the mechanical properties, and hence functionality, of tissues originating from human material are more difficult to control. On-line evaluation of tissue properties during culture or more early cellular markers to predict the properties of autologous tissues cultured for individual patients are, therefore, of utmost importance for future clinical application of autologous heart valve tissue engineering. As an example, this study shows that α-smooth muscle actin might be an indicator of tissue mechanical properties.Regenerative Medicine 01/2012; 7(1):59-70. · 3.72 Impact Factor -
Article: Sequential use of human-derived medium supplements favours cardiovascular tissue engineering.
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ABSTRACT: For clinical application of tissue engineering strategies, the use of animal-derived serum in culture medium is not recommended, because it can evoke immune responses in patients. We previously observed that human platelet-lysate (PL) is favourable for cell expansion, but generates weaker tissue as compared to culture in foetal bovine serum (FBS). We investigated if human serum (HS) is a better human supplement to increase tissue strength. Cells were isolated from venous grafts of 10 patients and expanded in media supplemented with PL or HS, to determine proliferation rates and expression of genes related to collagen production and maturation. Zymography was used to assess protease expression. Collagen contraction assays were used as a two-dimensional (2D) model for matrix contraction. As a prove of principle, 3D tissue culture and tensile testing was performed for two patients, to determine tissue strength. Cell proliferation was lower in HS-supplemented medium than in PL medium. The HS cells produced less active matrix metallo-proteinase 2 (MMP2) and showed increased matrix contraction as indicated by gel contraction assays and 3D-tissue culture. Tensile testing showed increased strength for tissues cultured in HS when compared to PL. This effect was more pronounced if cells were sequentially cultured in PL, followed by tissue culture in HS. These data suggest that sequential use of PL and HS as substitutes for FBS in culture medium for cardiovascular tissue engineering results in improved cell proliferation and tissue mechanical properties, as compared to use of PL or HS apart.Journal of Cellular and Molecular Medicine 06/2011; 16(4):730-9. · 4.13 Impact Factor
