Biomimetic Electrospun Scaffold-Based In Vitro Model Resembling the Hallmarks of Human Myocardial Fibrotic Tissue

Adverse remodeling post-myocardial infarction is hallmarkedbythe phenotypic change of cardiac fibroblasts (CFs) into myofibroblasts(MyoFs) and over-deposition of the fibrotic extracellular matrix (ECM)mainly composed by fibronectin and collagens, with the loss of tissueanisotropy and tissue stiffening. Reversing cardiac fibrosis representsa key challenge in cardiac regenerative medicine. Reliable in vitro models of human cardiac fibrotic tissue could beuseful for preclinical testing of new advanced therapies, addressingthe limited predictivity of traditional 2D cell cultures and animal in vivo models. In this work, we engineered a biomimetic in vitro model, reproducing the morphological, mechanical,and chemical cues of native cardiac fibrotic tissue. Polycaprolactone(PCL)-based scaffolds with randomly oriented fibers were fabricatedby solution electrospinning technique, showing homogeneous nanofiberswith an average size of 131 +/- 39 nm. PCL scaffolds were thensurface-functionalized with human type I collagen (C1) and fibronectin(F) by dihydroxyphenylalanine (DOPA)-mediated mussel-inspired approach(PCL/polyDOPA/C1F), in order to mimic fibrotic cardiac tissue-likeECM composition and support human CF culture. BCA assay confirmedthe successful deposition of the biomimetic coating and its stabilityduring 5 days of incubation in phosphate-buffered saline. Immunostainingfor C1 and F demonstrated their homogeneous distribution in the coating.AFM mechanical characterization showed that PCL/polyDOPA/C1F scaffolds,in wet conditions, resembled fibrotic tissue stiffness with an averageYoung's modulus of about 50 kPa. PCL/polyDOPA/C1F membranessupported human CF (HCF) adhesion and proliferation. Immunostainingfor alpha-SMA and quantification of alpha-SMA-positive cells showedHCF activation into MyoFs in the absence of a transforming growthfactor beta (TGF-beta) profibrotic stimulus, suggesting theintrinsic ability of biomimetic PCL/polyDOPA/C1F scaffolds to sustainthe development of cardiac fibrotic tissue. A proof-of-concept studymaking use of a commercially available antifibrotic drug confirmedthe potentialities of the developed in vitro modelfor drug efficacy testing. In conclusion, the proposed model was ableto replicate the main hallmarks of early-stage cardiac fibrosis, appearingas a promising tool for future preclinical testing of advanced regenerativetherapies.