Heart disease is currently the most significant cause of morbidity and mortality worldwide, which accounts for approximately 33% of all deaths. Recently, a promising and alchemy-like strategy has been developed called direct cardiac reprogramming, which directly converts somatic cells such as fibroblasts to cardiac lineage cells such as cardiomyocytes (CMs), termed induced CMs or iCMs. The first in vitro cardiac reprogramming study, mediated by cardiac transcription factors (TFs) -Gata4, Tbx5 and Mef2C-, was not enough efficient to produce an adequate number of fully reprogrammed, functional iCMs. As a result, numerous combinations of cardiac TFs exist for direct cardiac reprogramming of mouse and human fibroblasts. However, the efficiency of direct cardiac reprogramming remains low. Recently, a number of cellular and molecular mechanisms have been identified to increase the efficiency of direct cardiac reprogramming and the quality of iCMs. For example, microgrooved substrate, cardiogenic growth factors [VEGF, FGF, BMP4 and Activin A], and an appropriate stoichiometry of TFs boost the direct cardiac reprogramming. On the other hand, serum, TGFβ signaling, activators of epithelial to mesenchymal transition, and some epigenetic factors (Bmi1 and Ezh2) are barriers for direct cardiac reprogramming. Manipulating these mechanisms by the application of boosters and removing barriers can increase the efficiency of direct cardiac reprogramming and possibly make iCMs reliable for cell-based therapy or other potential applications. In this review, we summarize the latest trends in cardiac TF-or miRNA-based direct cardiac reprogramming and comprehensively discuses all molecular and cellular boosters and barriers affecting direct cardiac reprogramming.3

Cell therapy is one of the promising approaches used against type1 diabetes. Efficient generation of Human embryonic stem cell (hESC)-derived pancreatic progenitors (PPs) is of great importance. Since signaling pathways underlying human pancreas development is not yet fully understood, various differentiation protocols are conducted each considering variable duration, timing and concentrations of growth factors and small molecules. Therefore, we compared two PP differentiation protocols in static suspension culture. We tested modified protocols developed by Pagliuca et al. (protocol-1) and Royan researchers (protocol-2) until early PP stage. The morphological changes of hESC aggregates during differentiation, and also gene and protein expression after differentiation were evaluated. Different morphological structures were formed in each protocol. Quantitative gene expression analysis, flow cytometry and immunostaining revealed a high level of PDX1 expression on day 13 of Royan’s differentiation protocol compared to protocol-1. Our data showed that using protocol-2, cells were further differentiated until day16 showing higher efficiency of early PPs. Moreover, protocol-2 is able to produce hESCs-PPs in a static suspension culture. Since protocol-2 is inexpensive in terms of media, growth factors and chemicals, it can be used for massive production of PPs using static and dynamic suspension cultures.