Characterization of sarcoma-like cells derived from endarterectomized tissues from patients with CTEPH and establishment of a mouse model of pulmonary artery intimal sarcoma

: In general, intravascular thrombus formation in the pulmonary arteries is considered to be the most common cause of chronic thromboembolic pulmonary hypertension (CTEPH). The current mainstay of therapy for patients with CTEPH is pulmonary endarterectomy (PEA). Recently, the existence of myofibroblast-like cells in endarterectomized tissues has been demonstrated. At the 2nd passage of these myofibroblast-like cells, a pleomorphic cell type was isolated. Pulmonary intimal sarcoma is a very uncommon neoplastic tumor thought to originate from subendothelial-mesenchymal cells of the pulmonary vascular wall. Because these pleomorphic cells were isolated from the pulmonary vascular beds, it is believed that the analysis of these cells may contribute to the understanding of pulmonary intimal sarcoma. We isolated cells from the endarterectomized tissue from patients with CTEPH and identified one type as sarcoma-like cells (SCLs). The SCLs were characterized as hyperproliferative, anchorage-independent, invasive and serum-independent. Moreover, C.B-17/lcr-scid/scidJcl mice injected subcutaneously with SCLs developed solid, undifferentiated tumors at the site of injection, and those injected intravenously with SCLs via the tail vein developed tumors which grew along the intimal surface of the pulmonary vessels, thus, demonstrating the high tumorigenic potential of these cells. The behavior of SCLs indicated that these cells may have a vascular cell-like potential which can affiliate them with the intimal surface of the pulmonary artery, and which may be shared with pulmonary intimal sarcoma. A further investigation of this mouse model with SCLs may elucidate the mechanism(s) underlying the development of pulmonary intimal sarcoma.