Laser direct-write patterning influences early embryonic stem cell differentiation

An important objective in stem cell research is controlling differentiation of pluripotent stem cells to a desired fate. Previous research in this area has focused on directing differentiation by manipulating morphogens and substrate material/mechanics. However, cell-cell signaling, whether by contact or paracrine signaling, also influences differentiation. One promising direction by which cell-cell signaling can be manipulated is through cellular patterning. Using mouse embryonic stem cells (mESCs) as a model system, this study investigates patterning mESCs in colonies of controlled size and spacing, to examine the effect of patterning on differentiation. Laser direct-write was used to pattern mESCs in an array of small colonies, and cells were permitted to spontaneously differentiate for five days. Expression levels of seven select genes were compared to those of randomly seeded mESCs, and mESCs from conventional hanging drop culture. Analysis of variance showed significant differences in some genes examined, including mesoderm and ectoderm markers, indicating that the initial spatial arrangement of cells influences differentiation of pluripotent stem cells. A multivariate linear discriminant analysis was used to classify input populations, and suggested how genes may be affected by spatial patterning.