Method to deliver molecules within embryonic stem cells improves differentiation

Fluorescence microscopy image overlaid with phase image to display incorporation of microspheres (red stain) in embryoid bodies (gray circles). New research shows that delivering molecules via biodegradable microspheres enhances the... Click here for more information.

“Many researchers add soluble factors to the culture dish medium to direct differentiation, but this does not accurately mimic the time and location of signaling events present in normal development, and may contribute to heterogeneous differentiation,” said McDevitt. “Our method focuses on incorporating the differentiation factors directly into the cell aggregates in order to have a more controlled mechanism of presentation.”

The research team – which also includes graduate students Richard Carpenedo and Andrés Bratt-Leal and undergraduate students Ross Marklein and Scott Seaman – fabricated biodegradable polymer microspheres that could contain growth factors, proteins or other small molecules.

McDevitt’s team tested the impact of the poly(lactic-co-glycolic acid) (PLGA) microspheres on embryonic stem cell differentiation under different conditions by varying the microsphere-to-cell ratio and speed at which the aggregate cells were mixed with the microspheres. They also included a fluorescent dye in the microspheres so the degree of incorporation of the microspheres within the embryoid bodies could be assessed using fluorescent microscopy and spectroscopy.

The results revealed that the microspheres were incorporated into embryoid bodies under a variety of mixing conditions, but that slower rotary speeds and higher microsphere-to-cell ratios resulted in a greater degree of incorporation.