Female fibroblast activation is estrogen-mediated in sex-specific 3D-bioprinted pulmonary artery adventitia models
Pulmonary arterial hypertension (PAH) impacts male and female patients in different ways. Female patients exhibit a greater susceptibility to disease (4:1 female-to-male ratio) but live longer after diagnosis than male patients. This complex sexual dimorphism is known as the estrogen paradox. Prior studies suggest that estrogen signaling may be pathologic in the pulmonary vasculature and protective in the heart, yet the mechanisms underlying these sex-differences in PAH remain unclear. PAH is a form of a pulmonary vascular disease that results in scarring of the small blood vessels, leading to impaired blood flow and increased blood pressure. Over time, this increase in blood pressure causes damage to the heart. Many previous studies of PAH relied on male cells or cells of undisclosed origin for in vitro modeling. Here we present a dynamic, 3D-bioprinted model that incorporates cells and circulating sex hormones from female patients to specifically study how female patients respond to changes in microenvironmental stiffness and sex hormone signaling. Poly(ethylene glycol)-alpha methacrylate (PEGMA)-based hydrogels containing female human pulmonary artery adventitia fibroblasts (hPAAFs) from idiopathic PAH (IPAH) or control donors were 3D bioprinted to mimic pulmonary artery adventitia. These biomaterials were initially soft, like healthy blood vessels, and then stiffened using light to mimic vessel scarring in PAH. These 3D-bioprinted models showed that stiffening the microenvironment around female IPAH hPAAFs led to hPAAF activation. On both the protein and gene-expression levels, cellular activation markers significantly increased in stiffened samples and were highest in IPAH patient-derived cells. Treatment with a selective estrogen receptor modulator reduced expression hPAAF activation markers, demonstrating that hPAAF activation is a one pathologic response mediated by estrogen signaling in the vasculature, validating that drugs currently in clinical trials could be evaluated in sex-specific 3D-bioprinted pulmonary artery adventitia models.