Angiogenesis gene expression in murine endothelial cells during post-pneumonectomy lung growth

Abstract

Although blood vessel growth occurs readily in the systemic bronchial circulation, angiogenesis in the pulmonary circulation is rare. Compensatory lung growth after pneumonectomy is an experimental model with presumed alveolar capillary angiogenesis. To investigate the genes participating in murine neoalveolarization, we studied the expression of angiogenesis genes in lung endothelial cells. After left pneumonectomy, the remaining right lung was examined on days 3, 6, 14 and 21days after surgery and compared to both no surgery and sham thoracotomy controls. The lungs were enzymatically digested and CD31+ endothelial cells were isolated using flow cytometry cell sorting. The transcriptional profile of the CD31+ endothelial cells was assessed using quantitative real-time polymerase chain reaction (PCR) arrays. Focusing on 84 angiogenesis-associated genes, we identified 22 genes with greater than 4-fold regulation and significantly enhanced transcription (p <.05) within 21 days of pneumonectomy. Cluster analysis of the 22 genes indicated that changes in gene expression did not occur in a single phase, but in at least four waves of gene expression: a wave demonstrating decreased gene expression more than 3 days after pneumonectomy and 3 sequential waves of increased expression on days 6, 14, and 21 after pneumonectomy. These findings indicate that a network of gene interactions contributes to angiogenesis during compensatory lung growth.

Mechanostructural adaptations preceding postpneumonectomy lung growth

“…Our studies demonstrated 1) significant displacement of the heart and cardiac lobe within 3 days of surgery, and 2) coincident changes in peripheral lung mechanics. The changes in both the anatomic configuration of the thorax and the impedance measurements within the lung preceded the previously described peaks in growth-associated gene transcription [13, 15]. Further, the peripheral mechanical changes in the lung resolved with compensatory growth.…”

“…Recent studies of post-pneumonectomy lung cells [12], including endothelial cells [13, 14] and alveolar macrophages [15], have demonstrated an unexpected transcriptional time course; that is, gene transcription and cell proliferation that are minimal at 3 days, but peak 6 to 7 days after pneumonectomy. Distinct from the stretch responses studied in vitro—typically detected within hours of the stretch signal—these results indicate that post-pneumonectomy mechanics may not be optimally characterized as an immediate one-time stretch signal, but rather as dynamic anatomical and mechanical adaptations to the post-pneumonectomy thorax that occur over days to weeks.…”

CD34+ Progenitor to Endothelial Cell Transition in Post-Pneumonectomy Angiogenesis

“…Within 10 to 14 days of pneumonectomy, there is a significant increase in the total number of endothelial cells (29). This increase in endothelial cells parallels a 25% and 33% increase in the number of alveoli at Days 6 and 21 following pneumonectomy, respectively (7).…”

“…Moreover, the unique structure of the lung facilitated not only the isolation of these migrating progenitor cells, but also the characterization of their transcriptional profile. Our study demonstrated that blood-derived cells, expressing the CD34 surface molecule, directly contributed to murine postpneumonectomy angiogenesis, based on several lines of evidence: (1) The peak of CD34 1 cell migration was at 7 days-timing that coincided with the peak of lung angiogenesis (29). (2) Approximately 17.0% of migrating CD34 1 cells were undergoing active cell division.…”

Peroxisome Proliferator-activated Receptor-α-mediated Transcription of miR-199a2 Attenuates Endothelin-1 Expression via Hypoxia-inducible Factor-1α

“…Red cells were lysed using a blood cell lysis buffer (BD PharmLyse, BD Biosciences) as described (30). Lung single cell suspensions were co-stained with CD31 and CD45 antibodies (BD Biosciences), and CD31ϩ cells were sorted out of the CD45 cell population.…”