PromoCell's Endothelial Cell Growth Medium (C-22010) is a complete medium that can be used for the culture of HUVEC after addition of the SupplementMix.
Addition of extra FCS is not necessary. The SupplementMix contains FCS (2% v/v final concentration); recombinant growth factors; hormones; and a bovine brain extract that together have mitogenic effects on endothelial cells.
Epidermal Growth Factor (EGF) and hydrocortisone have been reported to have a synergistic effect on the growth of microvascular endothelial cells. Accordingly if you remove the hydrocortisone the proliferation of HDMEC is clearly affected.