Conclusions
The permeability of low and high passage hCB-ECs and HAECs initially increases in response to oxidative stress. hCB-ECs, but not HAECs, were able to recover from the stress 24 hours later. Early passage hCB-ECs were more susceptible to exogenous H2O2 than late passage hCB-ECs. The increase in permeability of hCB-ECs to H2O2 also correlated with decreased cell proliferation and changes in cell junctions.
Methods
Human umbilical cord blood derived endothelial cells (hCB-ECs) and human aortic endothelial cells (HAECs) were treated with 200 μM H2O2 and permeability to FITC-bovine serum albumin was measured. Some samples were subsequently treated with 100μM 8-pCPT-2'-O-Me-cAMP, a cAMP analog that activates the Epac1-Rap1 pathway. Cell proliferation was measured with the EdU assay. Phase contrast, and immunofluorescence images were taken to observe morphological changes in cells after exposure to H2O2.
Purpose
We sought to determine the effect of stress-induced senescence on the permeability to albumin of aging endothelial progenitor cells.
Results
hCB-ECs exposed to H2O2 exhibited a significant increase in permeability, but their response differed from the HAECs. Low passage hCB-ECs had a permeability increase of about 82% (p<0.01) compared to aged cells which had a permeability increase of about 37% (p<0.05). This increase in permeability was reduced by treating the cells with 100 μM 8-pCPT-2'-O-Me-cAMP. The younger cells exhibited a significant decrease in proliferation after being subjected to various concentrations of H2O2 whereas the aged cells exhibited a more gradual decrease in the percent of cells in S-phase. These changes also correlated with changes in cell morphology and junction staining. When placed back in the original media, the morphology and permeability of the hCB-ECs returned to the control condition, while the HAECs did not. Conclusions: The permeability of low and high passage hCB-ECs and HAECs initially increases in response to oxidative stress. hCB-ECs, but not HAECs, were able to recover from the stress 24 hours later. Early passage hCB-ECs were more susceptible to exogenous H2O2 than late passage hCB-ECs. The increase in permeability of hCB-ECs to H2O2 also correlated with decreased cell proliferation and changes in cell junctions.