Fig. 3.

Repetitive, long-term BMP9 stimulation pushes the PAH lung microvascular endothelium into a mesenchymal phenotype. a Representative staining of confluent MVECs for the endothelial marker VE-cadherin, the mesenchymal marker transgelin (SM22α), and the cytoskeletal protein F-actin after repetitive BMP9 stimulation every 24 h for a total duration of three days. Bar graphs represent quantifications (n = 3) of VE-cadherin and SM22 intensity as well as F-actin fiber orientation. Statistical differences were determined by unpaired t tests. b Time-resolved impedance spectroscopic quantification of endothelial barrier function (resistance, n = 4). BMP9 was administered after 5 h preparative serum starvation with 1% FCS every 24 h for a total duration of three days (arrow heads). Bar graphs represent integrity and strength of cell–cell (Rb) and cell–matrix interactions (Alpha) mathematically modeled from the impedance data. N.A. indicates inability to model data because of too low impedance values. Multiple t tests with Holm–Sidak corrections were used to calculate statistics for resistance within the control or the respective PAH group. Two-way ANOVA with Tukey multiple comparison correction was used to calculate differences in adhesion strength between ctrl. and PAH samples at the individual time points