Endothelial colony-forming cell conditioned media promote angiogenesis in vitro and prevent pulmonary hypertension in experimental bronchopulmonary dysplasia.

Late-outgrowth endothelial colony-forming cells (ECFCs), a type of circulating endothelial progenitor cell (EPC), may contribute to pulmonary angiogenesis during development. Cord blood ECFCs from preterm newborns proliferate more rapidly than term ECFCs but are more susceptible to the adverse effects of hyperoxia. Recent studies suggest that bone marrow-derived EPCs protect against experimental lung injury via paracrine mechanisms independent of vascular engraftment. To determine whether human umbilical cord blood ECFCs from preterm and term newborns have therapeutic benefit in experimental neonatal lung injury, we isolated cord blood ECFCs from full-term and preterm newborns and prepared ECFC-conditioned medium (CM) to test its therapeutic benefit on fetal pulmonary artery endothelial cell (PAEC) proliferation and function as well as alveolar type 2 (AT2) cell growth. PAECs and AT2 cells were isolated from late-gestation fetal sheep. Additionally, we administered both ECFCs and ECFC-CM to bleomycin-exposed newborn rats, an experimental model of bronchopulmonary dysplasia (BPD). Both term ECFC-CM and preterm ECFC-CM promoted cell growth and angiogenesis in vitro. However, when ECFC-CM was collected during exposure to mild hyperoxia, the benefit of preterm ECFC-CM was no longer observed. In the bleomycin model of BPD, treatment with ECFC-CM (or CM from mature EC) effectively decreased right ventricular hypertrophy but had no effect on alveolar septation. We conclude that term ECFC-CM is beneficial both in vitro and in experimental BPD. During oxidative stress, preterm ECFC-CM, but not term ECFC-CM, loses its benefit. The inability of term ECFC-CM to promote alveolarization may limit its therapeutic potential.

Cord blood endothelial colony-forming cells from newborns with congenital diaphragmatic hernia.

Endothelial colony-forming cells (ECFCs) are decreased in the cord blood of preterm infants with moderate-to-severe bronchopulmonary dysplasia. We quantified ECFCs from infants with congenital diaphragmatic hernia, a neonatal disorder with severe lung hypoplasia. Unlike newborns who develop bronchopulmonary dysplasia, those with congenital diaphragmatic hernia had increased and highly-proliferative cord blood ECFCs.

Cord blood angiogenic progenitor cells are decreased in bronchopulmonary dysplasia.

Bronchopulmonary dysplasia (BPD), the chronic lung disease of prematurity, is associated with impaired vascular and alveolar growth. Antenatal factors contribute to the risk for developing BPD by unclear mechanisms. Endothelial progenitor cells, such as angiogenic circulating progenitor cells (CPCs) and late-outgrowth endothelial colony-forming cells (ECFCs), may contribute to angiogenesis in the developing lung. We hypothesise that cord blood angiogenic CPCs and ECFCs are decreased in preterm infants with moderate and severe BPD. We quantified ECFCs and the CPC/nonangiogenic-CPC ratio (CPC/non-CPC) in cord blood samples from 62 preterm infants and assessed their relationships to maternal and perinatal risk factors as well as BPD severity. The CPC/non-CPC ratio and ECFC number were compared between preterm infants with mild or no BPD and those with moderate or severe BPD. ECFC number (p<0.001) and CPC/non-CPC ratio (p<0.05) were significantly decreased in cord blood samples of preterm infants who subsequently developed moderate or severe BPD. Gestational age and birth weight were not associated with either angiogenic marker. Circulating vascular progenitor cells are decreased in the cord blood of preterm infants who develop moderate and severe BPD. These findings suggest that prenatal factors contribute to late respiratory outcomes in preterm infants.

Umbilical Cord Blood Circulating Progenitor Cells and Endothelial Colony-Forming Cells Are Decreased in Preeclampsia.

Preeclampsia (PE) is a pregnancy-specific disease characterized by the new onset of hypertension and proteinuria. Mothers with PE are known to develop endothelial dysfunction, but its effect on infants has been understudied, as newborns are often asymptomatic. Recent studies indicate that infants born from preeclamptic pregnancies develop endothelial dysfunction including higher blood pressure during childhood and an increased risk of stroke later in life. We hypothesize that PE reduces the number and function of fetal angiogenic progenitor cells and may contribute to this increased risk. We quantified 2 distinct types of angiogenic progenitors, pro-angiogenic circulating progenitor cells (CPCs) and endothelial colony-forming cells (ECFCs), from the umbilical cord blood of preeclamptic pregnancies and normotensive controls. Pro-angiogenic and nonangiogenic CPCs were enumerated via flow cytometry and ECFCs by cell culture. Additionally, we studied the growth, migration, and tube formation of ECFCs from PE and gestational age-matched normotensive control pregnancies. We found that PE resulted in decreased cord blood pro-angiogenic CPCs and ECFCs. Nonangiogenic CPCs were also decreased. Preeclamptic ECFCs demonstrated decreased growth and migration but formed tube-like structures in vitro similar to controls. Our results suggest that the preeclamptic environment alters the number and function of angiogenic progenitor cells and may increase the risk of later vascular disease.

Gamma-irradiation-induced DNA damage checkpoint activation involves feedback regulation between extracellular signal-regulated kinase 1/2 and BRCA1.

Previous studies from our laboratory have shown that the activation of G(2)-M checkpoint after exposure of MCF-7 breast cancer cells to gamma-irradiation (IR) is dependent on the activation of extracellular signal-regulated kinase 1/2 (ERK1/2) signaling. Studies presented in this report indicate that IR exposure of MCF-7 cells is associated with a marked increase in expression of breast cancer 1 (BRCA1) tumor suppressor, an effect that requires ERK1/2 activation and involves posttranscriptional control mechanisms. Furthermore, reciprocal coimmunoprecipitation, as well as colocalization studies, indicate an interaction between BRCA1 and ERK1/2 in both nonirradiated and irradiated cells. Studies using short hairpin RNA targeting BRCA1 show that BRCA1 expression is necessary for IR-induced G(2)-M cell cycle arrest, as well as ERK1/2 activation in MCF-7 cells. Although BRCA1 expression is not required for IR-induced phosphorylation of ataxia telangiectasia mutated (ATM)-Ser1981, it is required for ATM-mediated downstream signaling events, including IR-induced phosphorylation of Chk2-Thr68 and p53-Ser20. Moreover, BRCA1 expression is also required for IR-induced ATM and rad3 related activation and Chk1 phosphorylation in MCF-7 cells. These results implicate an important interaction between BRCA1 and ERK1/2 in the regulation of cellular response after IR-induced DNA damage in MCF-7 cells.