Figure 3.

Cytocompatibility evaluation of decellularized heart ventricles. (A) Direct contact assay of decellularized ventricles (DVs) with human bone marrow mesenchymal stem cells (indicated as Cells). Phenotype and number of cells in contact with DVs (a, d, and g) were similar to those cultivated directly on plastics (b, e, and h) at all time points considered (24, 48, and 72 h). In direct contact with DVs, cells were shown to progressively polarize toward the decellularized tissues (a, d, and g). In the presence of glue, mesenchymal stem cells showed critical signs of sufferance and death (c, f, and i), immediately losing any morphological hallmarks. The DV scaffolds are visible in the upper right corner of a, d, and g, whereas the glue spots can be seen in the same position of c, f, and i. Magnification bars: 100 μm. (B) Cell cytotoxicity. Lactate dehydrogenase (LDH) activity in mesenchymal stem cells in direct contact with DVs normalized to those in culture plastics was negligible for all time points considered (24, 48, and 72 h, as well as 7, 10, and 14 days), differently from the same cells in the presence of glue, for which the value was 100%. (B) Cell viability. At each time point (24 h and 7 and 14 days), no significant alteration in the proliferation activity of mesenchymal stem cells was observed after contact with DVs with respect to the plastic culture support, as measured with MTS colorimetric assay. Conversely, glue significantly reduced cell proliferation with respect to the other culture conditions. Data are expressed as mean ± standard deviation (****, p < 0.0001).