Three-dimensional culture may promote cell reprogramming.

Stem cells reside in stem cells niches, which maintain the balance of self-renewal and differentiation of stem cells. In stem cell niches, cell-cell, cell-extracellular matrix interactions and diffusible signals are important elements. However, another pivotal element is that localized and diffusible signals are all organized as three-dimensional (3-D) structures, which is easily neglected by in vitro cell biology research. Under 3-D culture conditions, the morphology of cells exhibited differently from cultured in traditional two-dimensional (2-D) conditions. Under 3-D culture conditions, the self-renewal and pluripotency of neural stem cells (NSCs) and bone marrow mesenchymal stem cells (BMSCs) were enhanced compared with culturing under 2-D conditions. 3-D cultures could change the transcriptional profile of NSCs compared with 2-D cultures. We hypothesized that 3-D cultures could reprogram mature cells such as fibroblasts to an immature state, like the pluripotent stem cells. The primary results indicated that several ES marker genes were upregulated by 3-D cultures. Though further experiments are needed, this work may provide a method of reprogramming mature cells without gene modifications.