[Effects of methyl β cyclodextrin on the proliferation and transdifferentiation of type II alveolar epithelial cells]

To study the destructive effects of the membrane lipid microdomain with methyl β cyclodextrin (MβCD) on the proliferation, transdifferentiation and cell cycle of type II alveolar epithelial cell (AEC II).

The membrane lipid microdomain of AEC II was destroyed by MβCD (MβCD interference group) in vitro, and then cultured with DMEM as control. Cell number was counted with hemacytometer; the proliferation rate was measured by methyl thiazolyl tetrazolium (MTT); flow cytometry was used to assay the cell cycle. The expressions of AEC II specific surfactant protein-C (SP-C) and AECI specific aquaporin 5 (AQP5) were detected by immunofluorescence and Western blotting analyses.

Compared with control group, cell number and the cell proliferation was decreased in MβCD interference group at 24, 48 and 72 hours after interaction [cell numbers (×10(6)/ml): 2.74±0.56 vs. 8.05±0.92, 4.45±0.68 vs. 10.52±0.81, 7.82±0.59 vs. 11.39±0.81; MTT results (A value): 0.25±0.20 vs. 0.45±0.02, 0.35±0.03 vs. 0.54±0.28, 0.48±0.04 vs. 0.59±0.05, all P<0.01]. MβCD could increase the percentage of cells in G0/G1 phases and decreased the percentage in S phases at 24 hours [G0/G1 phases: (60.06±1.65)% vs. (43.43±3.59)%; S phases: (16.20±2.17)% vs. (34.07±2.63)%, both P<0.05 ]. Incubation of AEC II with MβCD resulted in up regulation of the expression of SP-C (0.54±0.04 vs. 0.47±0.03, 0.19±0.03 vs. 0.06±0.02) and down regulation of AQP5 (0.30±0.04 vs. 0.43±0.06, 0.39±0.04 vs. 0.59±0.04) at 48 hours and 72 hours after interaction (P<0.05 or P<0.01).

The destruction of membrane lipid microdomain by the MβCD can inhibit proliferation and transdifferentiation of AEC II, and induce cell cycle arrest in G1 phase.