Figure 8.1: Prevascularization of a cardiac patch created in affinity-binding alginate scaffolds on the omentum improves its therapeutic outcome. F. Pacing through the scar electrode in hearts treated with an omentum-generated patch trigger synchronized beating of the healthy right ventricle, suggesting electrical integration of the patch. (G) Comparison of signal amplitude in the scar zone after grafting an omentum-generated patch (black) or in stitched hearts (white). H. Comparison of capture threshold intensity in hearts grafted with an omentum-generated patch (black) or only stitched (white). I-K. Cardiac function evaluation by 2D echocardiography of infarcted hearts after treatment with a stitch (sham), implantation of in vitro-grown patch, empty patch grown on the omentum (Om), or omentumgenerated cardiac patch (Om+): comparison of FAC (I) change, LVEDD (J), and LVESD (K). Changes were calculated as follows: [(values obtained after four weeks – baseline values)/baseline values] ×100%. Statistical evaluations were performed by unpaired t test and one-way ANOVA, P < 0.05. [19].

8.4SUMMARY AND CONCLUSIONS

This chapter deals with a major issue in bioengineering of functional cardiac patches—the need for vascularization of the cell constructs before subsequent implantation into the infarct. One strategy developed to address this critical need relies on the addition of endothelial cells (ECs) to the cell mixture, to promote vessel formation in the developed tissue. Further refinement of this strategy includes sequential cell seeding and the use of different scaffold compartments (i.e., in channeled scaffolds) to improve cell organization and formation of primitive vascular networks. An alternative strategy described is the use of the body as a bioreactor for more effective pre-vascularization. Omentum-vascularized cardiac patches have shown improved electrical integration and beneficial effects on cardiac function in rat MI model. Collectively, the already available data clearly show

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several advancements toward the introduction of vascular beds and networks into the engineered cardiac patches. Further development will allow generation of thick cell constructs, with a size suitable for clinical implementation in patients.

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