Differences in collateral-dependent muscle perfusion may explain efficacy variation in clinical angiogenic gene therapy trials

Introduction: Replacing loss of cardiac cells after ischemic heart injuries using a tridimensional biocompatible scaffolds for cell delivery could be assimilated to a microenvironment mimicking culture device directly in contact with the targeted area. Our main work was to modify those scaffolds properties to improve cardiac commitment of human embryonic stem cells (hESC). Experimental Procedures: We modified scaffolds physical and chemical properties to support human embryonic stem cells (hESCs) differentiation toward the cardiac lineage, by incorporating gelatin and Fucoidan, and analyzed hESC cardiac commitment markers expression by qPCR and histological analysis. Results: Fucoidan scaffolds ability to locally concentrate and slowly release TGF-b and TNF-a was confirmed by Luminex technology. They support significantly higher expression of the early step of embryonic cardiac differentiation markers: NKX2.5 (p < 0.05), MEF2C (p < 0.01), and GATA4 (p < 0.01). We also found that Fucoidan scaffolds supported the late stage of embryonic cardiac differentiation marked by ANF expression (p < 0.001). Moreover, thin connecting smooth muscle cells filaments enabled maintenance of beating areas for up to 6 months. Conclusion Perspectives: Porous scaffolds are a promising method to improve cells delivery to damaged myocardium. Absence of mechanical stress in the soft hydrogel impaired sarcomere formation, as confirmed by cardiac muscle myosin MYH6 and sarcomeric a-actinin analysis. As a consequence, further scaffolds chemical stiffening or combination with mechanical stress, could enhance sarcomere formation at terminal stages of differentiation (TEA. 2014 doi: 10.1089)