FK506 binding protein like, FKBPL, as a novel therapeutic target in 2D and 3D bioprinted, models of cardiac fibrosis

Cardiac fibrosis characterised by increased collagen deposition and extracellular matrix (ECM) remodeling is one of the main causes of heart failure. Inflammation and hypoxia are key processes leading to cardiac fibrosis although the mechanisms are poorly understood. In this study, we developed an innovative 3D bioprinted model of cardiac fibrosis using tunable matrices. The role of an anti-angiogenic protein, FK506 binding protein like (FKBPL) was then elucidated, for the first time, using both 2D and 3D bioprinted, models of cardiac fibrosis. 3D bioprinted model of cardiac fibrosis was developed using fetal fibroblast cells (HFF08), customised ECM cardiac components and pro-fibrotic/hypoxic factors (TGF-β, 10 ng/ml, DMOG, 1 mM) ± FKBPL mimetic (AD-01, 100 mM). In parallel, 2D in vitro models were also employed. In the 3D bioprinted model, fibroblasts formed networks spontaneously, which were stimulated by all treatments (p < 0.05–0.0001). This was in conjunction with a trend towards reduced FKBPL expression, particularly in the presence of DMOG/AD-01 treatment. In 2D cell culture, AD-01 potentiated TGF-β-induced col1a1 (p < 0.0001) and mmp2 mRNA (p < 0.05) expression whereas DMOG or reduced FKBPL expression with AD-01 abrogated this (p < 0.05–0.001). Following siRNA FKBPL transfection, α-SMA was reduced (p < 0.05). This 3D bioprinted model of cardiac fibrosis in conjunction with 2D cell models could be used for biomarker and drug therapy screening towards accelerating the development of treatments for this hard-to-treat condition. Low FKBPL expression could be protective in cardiac fibrosis through the reduction in collagen production and α-SMA expression, or TGF-β/HIF-1α-mediated effects. Therapeutic strategies that inhibit FKBPL should be explored to abrogate cardiac fibrosis.