Figure 7. The SARS-CoV-2 S protein effects on cardiac PC function are CD147-dependent.

(A) Intracellular ERK1/2 phosphorylation/activation. Cardiac PCs were cultured for 24 h under serum and growth factors deprivation and then exposed for 1 h to the S protein (1 μg/ml – 5.8 nM) or vehicle. For receptor blockade, PCs were pre-incubated with antibodies anti-ACE2 or anti-CD147 for 1 h before the S treatment. The bar-graph reports the ratio between phospho-ERK1/2 (Thr²⁰²/Tyr²⁰⁴) and total ERK1/2, as measured by ELISA, and expressed as fold-change versus vehicle. n=4 patients’ PCs. (B) Migration wound closure assay. A scratch was created in confluent PCs and images taken at baseline. Where the blockade of CD147 was required, cells were pre-incubated with an antibody anti-CD147 for 1 hr. Then, the S protein (1 μg/ml – 5.8 nM) or vehicle were added to the system for 24 h. Final images were recorded. The surface of wound closure was calculated as % of the baseline area and expressed as fold-change vs vehicle. n=5 patients’ PCs. (C) Matrigel assay. Where the blockade of CD147 was required, cardiac PCs were pre-incubated with an antibody anti-CD147 for 1 h. Afterwards, CAECs and cocultures of CAECs + PCs were incubated on the top of Matrigel for 5 h, in the presence of the S protein (1 μg/ml – 5.8 nM) or vehicle. Representative images of CAECs + PCs cocultures. The bar-graphs indicate the total tube length per imaging field, expressed as fold-change vs CAEC in single culture (dotted line at y = 1). n=5 patients’ PCs. Graphs indicate individual values and means ± SEM. *P<0.05, **P<0.01.