Effect of Dexamethasone Levels on Osteogenic Differentiation of Wharton's Jelly Stem Cells from the Human Umbilical Cord

Erica Brown and Vassilios I. Sikavitsas. Chemical, Biological, and Materials Engineering, University of Oklahoma, 100 E Boyd Str, RM T-335, Norman, OK 73019

Wharton's Jelly Stem Cells (WJSC) constitutes the mucuoid connective tissue surrounding the perivascular region of the human umbilical cord. These cells have been characterized as a primitive stem cell population as they possess differentiation capabilities similar to that of adult stem cells. The aim of this study was to investigate WJSC for use as a novel allogenic cell source for regenerative bone therapies.

Experiments suggest osteogenic differentiation of Wharton's Jelly Stem Cells (WJSC) in static 2D and 3D cultures as evidenced by mineralization, alkaline phosphatase activity, and other phenotypic changes. Wharton's Jelly Stem cells, cultured with osteogenic media containing 10nm of dexamethasone in 2D static cultures, demonstrated a significant decrease in cell number after 7 days in comparison to control groups. This observation led us to study the influence of dexamethasone levels on osteogenic differentiation and to identify the optimal dexamethasone concentration in the cell culture that maximizes osteogenic differentiation without compromising the proliferative capacity of the cells.

For this reason 2D and 3D static cultures of WJSC were cultured in osteogenic media with dexamethasone concentrations of 10nM, 1nM, 0,1nM, and no dexamethasone for time periods of 4 and 7 days. An additional group was investigated in which WJSC cultures were spiked with osteogenic media containing dexamethasone at 10nM for 1 hour with a continuation of 71 hours in osteogenic media containing no dexamethasone.