(155d) Invited Talk:Differentiation of Cardiac Progenitor Cells Using Fibrous Scaffolds

Matrix mechanical properties-induced stem cell differentiation has attracted tremendous interest in the tissue engineering community, as cell differentiation can be simply controlled by matrix physical properties, without using complicated biochemical stimulation [1]. We investigated whether mechanical properties of the extracellular matrix-mimicking fibrous scaffolds can be modulated to direct stem cell differentiation into a cardiac lineage. The scaffolds were fabricated by electrospinning a polymer blend based on a highly soft poly(N-isopropylacrylamide) hydrogel and a relatively stiffer polyurethane. By varying ratio of the hydrogel and the polyurethane, scaffolds with three different stiffnesses were fabricated, i.e., 14 ± 3, 223 ± 33 and 463 ± 38 kPa. To investigate stem cell differentiation in these scaffolds, cardiosphere-derived cells (CDCs) - a type of emerging cardiac progenitor cell for cardiac therapy, were incorporated to the scaffolds, by simultaneously electrospinning polymer fibers and electrospraying cells. Cell growth and differentiation were characterized after a 7-day culture in a spinner flask. dsDNA (for live cells) results showed that CDCs remained alive in the scaffolds. CDC differentiation was characterized at the mRNA level by real time RT-PCR, and the protein level by immunohistochemistry. At the mRNA level, the expressions of cardiac markers cardiac troponin T (cTnT) and cardiac myosin heavy chain (MYH6) were significantly upregulated in all scaffolds. The CDCs also developed calcium channels (CACNA1c) that are necessary for imparting electrophysiological properties. The scaffold with modulus of 14.3 kPa most efficiently stimulated the differentiation. Immunohistochemical analysis demonstrated that CDCs in the scaffold with modulus of 14.3 kPa expressed both troponin I (cTnI) and connexin43 (CX43) markers at protein level. This study suggests that stiffness of 14.3 kPa may be ideal for CDCs to differentiate into a cardiac linage in a fibrous scaffold.