Three-dimensional culture of rat ovarian granulosa cells shows increased SPP1 and FGF7 expression through the PI3K/Akt pathway.

Ovarian granulosa cells (OGCs) play an essential role in the regulation of follicular growth and development. However, previous studies of OGCs have concentrated on traditional 2D cultures. In the present study, we used the hanging drop culture method to culture rat OGCs (rOGCs) and assessed the effects of 3D conditions on their proliferation and gene expression profiles. Compared with those grown in 2D conditions, rOGCs grown in 3D cultures showed a significantly different spatial cell distribution and cell alignment under electron microscopy. In particular, rOGCs in 3D cultures showed abundant rough and microvilli-like structures on their cell surface. Here, we showed that these cells grew slowly following 3D culture; the G0/G1-phase increased and the S- and G2/M-phases decreased. Using whole-transcriptome sequencing analysis, 501 genes were shown to have been significantly upregulated and 502 were shown to have been downregulated. Differentially expressed genes were most enriched in pathways involved in focal adhesion, MAPK, and PI3K/Akt signaling according to Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. Western blotting revealed that SPP1 and FGF7 in the PI3K/Akt pathway were significantly upregulated following 3D culture. These findings improve our understanding of OGCs in real 3D environments in vivo and provide possible avenues for future research on OGCs.