Substrate Rigidity Affects Cystoskeleton Conformation And Cell Junction Mode Of Hepatic Cell

Tissue sclerosis and extracellular matrix (ECM) protein deposition are main feature of liver fibrosis. Mechanical rigidity of the tissue has great impact on the biological behavior of cells in the liver. Substrate rigidity affect cell morphology, cystoskeleton conformation, assembly of focal adhesion and cell junction mode by mediate pro-stress in the cell. These behaviors have significance influence on maintenance of cell phaenotype. In this research, polyacrylamide substrate whose stiffness is controllable is prepared to investigate hepatic parenchymal cells biological behavior when they are cultured on substrate with different rigidity and ECM density. The role of tissue rigidity diversity in liver fibrosis process was also discussed.Object: Investigating the effect of substrate rigidity and ECM density on cell biological behaviors, by using polyacrylamide substrate to reveal the influence of the increased tissue stiffness on hepatic parenchymal cells during liver fibrosis.Method: Using microscopic morphological observation, and immunohisto -chemistry to probe cell morphology, cystoskeleton conformation, assembly of focal adhesion and cell junction mode of single cell or confluent cells cultured on polyacrylamide substrate with different rigidity and ECM density. Using image analysis software to quantify the results and imply the correlation between cell biological behavior and substrate rigidity.Results: Cell long axis/short axis value and deform factor differ significantly among different substrate rigidity. F-actin of cells on softer substrate concentrate at cell boundary while that of cells on harder substrate assembled into stress fiber. Cell junction modes varies on different substrate rigidity. Fluorescence intensity of E- cadherins decreased when raise the rigidity of substrate, paxillin (a focal adhesion protein ) shows contrary tendency. On soft substrate, confluent cells may gathered into tissue-like 3D structure, the phenomenon disappeared when ECM density augmentation; Cells on stiff substrate maintained spreading with the ECM density variation.Conclusion: 1. Substrate rigidity has great impact on hepatic parenchymal cells biological behavior. cystoskeleton conformation and cell junction mode correlate with cell morphology. 2. Interaction between cell-cell and cell-substrate compete with each other. The results are determined by substrate rigidity. 3. Increasing of ECM density may up-regulate cell adhesion, but make little impact on cystoskeleton conformation or cell junction mode.