Endothelial Progenitor Cells and Notch-1 Signaling as Markers of Alveolar Endothelium Regeneration in Pulmonary Emphysema

We studied the effects of elastase, cigarette smoke extract, D-galactosamine hydrochloride, and tyrosine kinase inhibitor SU5416 on endothelial progenitor cells and angiogenesis precursors, as well as on Notch-1 expression by immature endothelial cells. Simultaneously with pulmonary emphysema, different damaging factors with diverse mechanisms of action caused pathological changes in the microvascular network of the lungs and destroyed the alveolar endothelium in female C57Bl/6 mice. D-galactosamine hydrochloride disturbed mobilization of endothelial progenitor cells expressing VEGFR (CD45—CD309⁺) and angiogenesis progenitors (CD45^—CD309⁺CD117⁺) and their migration into emphysema expanded lungs. Elastase inhibited VEGFR-expressing endothelial progenitor cells, while cigarette smoke extract inhibited cells with CD45^—CD31⁺CD34⁺ phenotype. In pulmonary emphysema provoked by elastase or D-galactosamine hydrochloride, angiogenesis was provided by endothelial cells with CD45^—CD31⁺CD34⁺ phenotype, whereas in emphysema modeled with SU5416 or cigarette smoke extract, it was provided by the endothelial VEGFR-expressing cells and mature CD31⁺ endothelial cells, respectively. Replenishment of immature endothelial cells damaged by elastase and SU5416 involved Notch-1⁺ angiogenesis precursors and Notch-1⁺ endothelial progenitor cells with VEGFR.