Three-dimensional microfabricated scaffolds with cardiac extracellular matrix-like architecture

In recent years, research in the field of myocardial tissue engineering has advanced thanks to the development of new biomaterials and a more clear understanding of processes that are at the basis of cardiac tissue growth. However, classical porous scaffolds developed during these years to try to reconstruct and mimic heart function have proven to be inadequate because they are not able to reproduce the typical myocardial environment. One approach to increase functionality of tissue-engineered constructs relies on attempts to mimic the microarchitecture of natural tissues, since it is well known that topology is one of the principal stimuli that cells need to activate their functions. The aim of this work was the realization of three-dimensional microfabricated scaffolds, with cardiac extracellular matrix (ECM)-like architecture. For this purpose, samples of pig myocardium were decellularized, embedded in paraffin wax and analyzed under an optical microscope, in order to evaluate the geometrical features of the cardiac ECM. On the basis of these data, a simplified model of the cardiac ECM microarchitecture was designed. Microfabricated scaffolds were realized with Soft Lithography technique, using a bioartificial blend, based on alginate, gelatin and a novel poly(N-isopropylacrylamide)-based copolymer, which we synthesized. The scaffolds were characterized in terms of topological and mechanical properties. Moreover, cell adhesion, proliferation, and differentiation tests were performed. The microfabricated scaffolds showed they matched the anisotropic mechanical properties of adult human left ventricular myocardium, while at the same time being able to promote myoblast alignment in the absence of external stimuli.