Endothelial precursor cell-conditioned media (EPC-CM) derived from human embryonic stem cells (hESC) has various secreted cytokines such as epidermal growth factor (EGF), vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF). EPC-CM has been used as an effective material for pigmentation, erythema and wrinkles in clinical trials. However, the mechanism of action and effects of EPC-CM on cells and skin equivalents are unknown. In this study, we investigated the biological effects of the EPC-CM on keratinocytes 3D human skin equivalents.
Primary human epidermal keratinocytes were isolated from the newborn and adult foreskin. The effect of EPC-CM on keratinocytes was examined using doubling time, colony forming efficiency and K19 immunofluorescence. EPC-CM increased the colony forming efficiency of keratinocytes without increasing the doubling time. Macroscopic and histologic analyses were also performed to examine the effect of EPC-CM on 3D skin equivalents which were produced with fibroblasts and 2 types of keratinocytes, newborn and adult. Unlike the control medium, EPC-CM produced successful 3D skin equivalents when adult keratinocytes were used. Recovery effects of EPC-CM on ultraviolet B (UVB)-induced damage were evaluated on 3D skin equivalents. When EPC-CM was treated after UVB irradiation, protein levels of procollagen I and matrix metalloproteinase (MMP-1) were measured using Western blot analysis. Treatment of EPC-CM increased the expression of procollagen I and decreased the expression of MMP-1. To investigate the effect of EPC-CM on the collagen degradation by UVB in 3D skin equivalents, Masson’s trichrome staining was carried out. When EPC-CM was treated, staining intensity of the dermis showed higher than group irradiated with UVB. 
  From these results, the effect of EPC-CM on keratinocytes and 3D skin models were evaluated. EPC-CM induced the proliferation of epidermal keratinocytes and contributed to produce successful 3D skin models. EPC-CM also showed inhibitory effects of MMP-1 overexpression and collagen degradation in 3D skin models.

The effect of endothelial precursor cell-conditioned media on keratinocytes and 3D skin models