Substrate stiffness modulates cardiac fibroblast activation, senescence and proinflammatory secretory phenotype

Am J Physiol Heart Circ Physiol. 2023 Oct 27. doi: 10.1152/ajpheart.00483.2023. Online ahead of print.ABSTRACTIn vitro cultures of primary cardiac fibroblasts (CFs), the major extracellular matrix (ECM)-producing cells of the heart, are used to determine molecular mechanisms of cardiac fibrosis. However, the supraphysiologic stiffness of tissue culture polystyrene (TCPS) triggers conversion of CFs into an activated myofibroblast-like state, and serial passage of the cells results in the induction of replicative senescence. These phenotypic switches confound interpretation of experimental data obtained with cultured CFs. In an attempt to circumvent TCPS-induced activation and senescence of CFs, we utilized poly (ethylene glycol) (PEG) hydrogels as cell culture platforms with low and high stiffness formulations to mimic healthy and fibrotic hearts, respectively. Low hydrogel stiffness converted activated CFs into a quiescent state with reduced abundance of a-smooth muscle actin (a-SMA)-containing stress fibers. Unexpectedly, lower substrate stiffness concomitantly augmented CF senescence, marked by elevated senescence-associated b-galactosidase (SA-β-Gal) activity and increased expression of p16 and p21, which are antiproliferative markers of senescence. Using dynamically stiffening hydrogels with phototunable crosslinking capabilities, we demonstrate that premature, substrate-induced CF senescence is partially reversible. RNA-sequencing analysis revealed widespread transcript...
Source: American Journal of Physiology. Heart and Circulatory Physiology - Category: Physiology Authors: Source Type: research