Fractal Dimension as a Measure of Altered Actin Cytoskeleton in MC3T3-E1 Cells Under Simulated Microgravity Using 3-D/2-D Clinostats

• Published in: IEEE transactions on biomedical engineering Vol. 59; no. 5; pp. 1374 - 1380
• Main Authors: Qian, A. R., Li, D., Han, J., Gao, X., Di, S. M., Zhang, W., Hu, L. F., Shang, Peng
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.05.2012; Institute of Electrical and Electronics Engineers
• Subjects: Actin cytoskeleton; Actin Cytoskeleton - physiology; Actins - physiology; Animals; Biological and medical sciences; Cell Culture Techniques - instrumentation; Cell Line; Cell structures and functions; Cells (biology); clinorotation; Complexity theory; Cytoskeleton, cytoplasm. Intracellular movements; Fluorescence; fractal dimension; Fractals; Fundamental and applied biological sciences. Psychology; Gravity; Mice; Microscopy, Confocal; Microscopy, Fluorescence; Molecular and cellular biology; osteoblast; Osteoblasts - physiology; Real time systems; Real-Time Polymerase Chain Reaction; simulated microgravity; Software; Weightlessness; clinorotation; Rodentia; Contractile protein; Osteoarticular system; Vertebrata; Mammalia; Fractal dimension; Mouse; Actin; Animal; Morphology; Osteoblast; Cytoskeleton; Bone; Actin cytoskeleton; Microgravity; simulated microgravity; Biomedical engineering
• ISSN: 0018-9294; 1558-2531
• DOI: 10.1109/TBME.2012.2187785

Osteoblasts, the bone-forming cells, respond to various mechanical forces, such as stretch and fluid shear force in essentially similar ways. The cytoskeleton, as the load-bearing architecture of the cell, is sensitive to altered inertial forces. Disruption of the cytoskeleton will result in alteration of cellular structure and function. However, it is difficult to quantitatively illustrate cytoskeletal rearrangement because of the complexity of cytoskeletal structure. Usually, the morphological changes in actin organization caused by external stimulus are basically descriptive. In this study, fractal dimensions (D) analysis was used to quantify the morphological changes in the actin cytoskeleton of osteoblast-like cells (MC3T3-E1) under simulated microgravity using 3-D/2-D clinostats. The ImageJ software was used to count the fractal dimension of actin cytoskeleton by box-counting methods. Real-time PCR and immunofluroscent assays were used to further confirm the results obtained by fractal dimension analysis. The results showed significant decreases in D value of actin cytoskeleton, β-actin mRNA expression, and the mean fluorescence intensity of F-actin in osteoblast-like cells after 24 or 48 h of incubation under 3-D/2-D clinorotation condition compared with control. The findings indicate that 3-D/2-D clinorotation affects both actin cytoskeleton architecture and mRNA expression, and fractal may be a promising approach for quantitative analysis of the changes in cytoskeleton in different environments.