Unusual transduction response of progenitor-derived and mature endothelial cells exposed to laminar pulsatile shear stress.

Progenitor-derived endothelial cells (PDECs) isolated from human umbilical cord blood generate a great hope in the fields of vascular tissue engineering. Endothelial cells subjected to shear stress convert mechanical stimuli into intracellular signals that affect cellular functions. It is essential to ensure that PDECs are able to sense shear stress as mature endothelial cells from human saphenous veins (HSVECs) do with mitogen-activated protein (MAP) kinase and nuclear factor (NF)-kappaB signal transduction pathways. HSVECs and PDECs were seeded on glass slides coated with gelatin and exposed to 12 dyn/cm2 in a parallel-plate flow chamber. In both cell types, shear stress activated extracellular signal-related kinase (ERK)1/2 with a rapid time course (maximum 5 min) followed by a reduced phosphorylation, and p38 pathway. c-Jun N-terminal protein kinase (JNK) phosphorylation is observed only in PDECs. With respect to NF-kappaB translocation to the nucleus, the NF-kappaB pathway is not activated by flow in HSVECs and PDECs although interleukin-1alpha (IL-1alpha) activates this pathway in both cell types. In our experimental conditions, shear stress does not modify the nuclear translocation of NF-kappaB in HSVECs after IL-1alpha stimulation. It can be stated that PDECs are shear stress sensitive and capable of signal transduction as mature HSVECs are, despite the unusual transduction response of both cell types.