FIG. 4.

Dimensionality and medium composition interact to alter cell proliferation and lineage. Astrocytes were cultured on 2D collagen-coated coverslips and within 3D collagen gels in serum-containing or serum-free media for 4 days. (A) The overall total number of cells, in equivalent regions, was increased in the 3D serum-free culture condition. (B) EdU was used to label cells that were in S-phase as a measure of cell proliferation. Double immunohistochemistry for GFAP (red) and EdU (green) demonstrates that round and bipolar astrocytes were among the proliferative populations. Bar = 10 μm. (C) Analysis of the percent of the population that had incorporated EdU yielded an effect of dimensionality. (D) The distribution of morphologies of EdU⁺ cells was dependent upon medium composition and culture substrate dimension. Bars represent mean ± SEM from n > 3 samples; in each sample, n > 50 astrocytes were counted. An asterisk denotes a significant difference at the p < 0.05 level for an effect of substrate dimension. Color images available online at www.liebertpub.com/tea