Abstract 985: Sca-1+ Progenitors Derived from Stem Cells Differentiate into Endothelial Cells: Implications for Stem Cell-Based Therapy in the Injured Artery
Background: Embryonic stem (ES) cells have the ability to differentiate into somatic cells of all tissue types, which can be used for tissue engineering and repair of damaged organs. However, no successful procedure for producing a large number of endothelial cells (ECs) from ES cells with high purity is available, and little is known about the mechanisms of EC differentiation and their therapeutic potential for these stem cell-derived ECs in repairing injured artery. The aim of the present study is to establish a method for producing large number of endothelial cells (ECs) from embryonic stem cells (ESCs) and to understand the mechanisms of EC differentiation and their therapeutic potential in repairing injured arteries.
Methods and Results: To produce large number of ECs with higher purity, Sca-1+ cells isolated with magnetic beads from pre-differentiated ESCs were cultured in a-MEM containing 10ng/ml VEGF165 for a long period (21 days or more, defined as esEC). Immunofluorescence or FACS analysis revealed that esEC expressed full range of EC lineage-specific markers including CD31, CD106, CD144, Flk-1, Flt-1, and vWF. FACS analysis confirmed that 98.7% and 74.8% of esECs were CD31− and vWF-positive, respectively, and almost all the cells were positive for DiI-acLDL uptake. Interestingly, we found that histone deacetylase (HDAC3) was essential for VEGF-induced EC differentiation, as demonstrated by adenoviral HDAC3 gene transfer and HDAC3 siRNA knockdown experiments. Furthermore, when esEC mixed with Matrigel were subcutaneously implanted into mice, various vessel-like structures were observed. When esECs infected with adenovirus-LacZ were transplanted into injured mouse artery, they were found to form neo-endothelium that covered the injured areas (86%±13.6%), which resulted in a significant decrease in neointima lesions 2 weeks after injury (8,036 mm2±866 mm2 vs 30,026 mm2±2500 mm2, p<0.001).
Conclusions: We conclude that Sca-1+ cells can differentiate into functional ECs via activation of HDAC3, which accelerate reendothelialization of injured artery and reduce neointimal formation.