Polyelectrolyte multilayer films promote human cord blood stem cells differentiation into mature endothelial cells exhibiting a stable phenotype.

Background: recent studies in bio-engineering have showed the influence of Polyelectrolyte Multilayer (PEM) films on endothelial cells (ECs), especially poly(sodium-4-styrene-sulfonate) (PSS) and poly(allylamine hydrochloride) (PAH). They were tested either with human mature ECs or rabbit immature endothelial progenitor cells (EPCs), but never on human EPCs. In view to obtain an EC covered surface, human cord blood (HCB) EPCs were cultivated on PSS/PAH films.
Material and Methods: PEMs were obtained by 7 alternate depositions of cationic PAH and anionic PSS layers. HCB mononuclear cells were isolated by centrifugation through density gradient. 7 days after seeding on PEM, unattached cells were removed and adherent EPCs were cultivated in endothelial specific medium until P6. Appearance of CD31 and vWF was evaluated by confocal microscopy.
Results: EPCs not only successfully adhered on PEM, but also spread and proliferated. Moreover, cells differentiated into a typical endothelial cobblestone monolayer within 2 weeks. Immunostaining of CD31 and vWF confirmed the formation of an EC-like confluent monolayer. Furthermore, these cells showed after 6 passages a good phenotypic stability while reseeded on the PEM film.
Conclusion: these results show an easy way to obtain mature ECs from human stem cells, which may open new applications for a scaffold cellularization in tissue bio-engineering.