library_construction_protocol: Pulmonary artery tissues were placed in DMEM/F12(Gibco), and cut into small fragments and digested them with collagenase II (Invitrogen) for 2h at 37℃. After digestion, the obtained cells were filtered through a 70μm filter and collect it into a collection tube. Sequencing libraries were conducted using the BD Rhapsody Single-Cell Analysis System (BD Biosciences), following the manufacture's protocol.