Growth arrest of vascular smooth muscle cells in suspension culture using low-acyl gellan gum

Reversible suspension culture of human vascular smooth muscle cells using the functional biopolymer FP003

Human vascular smooth muscle cells (SMCs) are adherent cells, and they cannot survive without scaffolds in suspension culture. Here, we aimed to establish a suspension culture of SMCs using the functional biopolymer FP003 and to investigate the proliferation status of the cells. When SMCs were suspension cultured with FP003, their proliferation was inhibited with a viability of 75% until day 15. When SMCs were re-plated on plastic plates after suspension culture with FP003 for 48 h, the SMCs proliferated as in a normal plate culture. The SMCs cultured in suspension with FP003 showed a relatively low phosphorylation of retinoblastoma protein, low expression of cyclin D1, high proportion of G0/G1 phase cells, low proportion of S phase cells, and no obvious signs of apoptosis, indicating that this culture system inhibited progression from the G1 to S phase. This growth arrest was a reversible property that showed no significant changes in the expressions of the marker proteins α-smooth muscle actin and smooth muscle myosin heavy chain. These results suggest that human SMCs can be stably cultured in suspension with FP003 without losing their characteristics when they are cultured on plastic plates again.

Gellan Gum Promotes the Differentiation of Enterocytes from Human Induced Pluripotent Stem Cells

The evaluation of drug pharmacokinetics in the small intestine is critical for developing orally administered drugs. Caucasian colon adenocarcinoma (Caco-2) cells are employed to evaluate drug absorption in preclinical trials of drug development. However, the pharmacokinetic characteristics of Caco-2 cells are different from those of the normal human small intestine. Besides this, it is almost impossible to obtain primary human intestinal epithelial cells of the same batch. Therefore, human iPS cell-derived enterocytes (hiPSEs) with pharmacokinetic functions similar to human intestinal epithelial cells are expected to be useful for the evaluation of drug absorption. Previous studies have been limited to the use of cytokines and small molecules to generate hiPSEs. Dietary fibers play a critical role in maintaining intestinal physiology. We used gellan gum (GG), a soluble dietary fiber, to optimize hiPSE differentiation. hiPSEs cocultured with GG had significantly higher expression of small intestine- and pharmacokinetics-related genes and proteins. The activities of drug-metabolizing enzymes, such as cytochrome P450 2C19, and peptide transporter 1 were significantly increased in the GG treatment group compared to the control group. At the end point of differentiation, the percentage of senescent cells increased. Therefore, GG could improve the differentiation efficiency of human iPS cells to enterocytes and increase intestinal maturation by extending the life span of hiPSEs.