Single-Cell Biophysics: Measurement, Modulation, and Modeling

Single-Cell Biophysics: Measurement, Modulation, and Modeling

Poster Abstracts

83-POS Board 42 Traumatic Retraction of Neurons Regulated by Cell-Extracellular Matrix Adhesion Xueying Shao , Kwan Kei Wong, Yuan Lin. The University of Hong Kong, Hong Kong, Hong Kong. Damage to neural cells and retraction of axons during traumatic brain injury (TBI) are believed to trigger disintegration of the neural network and eventually lead to severe symptoms such as permanent memory loss and emotional disturbances. Unfortunately, a method allowing us to quantitatively characterize the traumatic retraction of neural cells as well identify key players involved is still lacking. In this study, we used a sharp atomic force microscope (AFM) probe to transect axons and trigger their retraction while, at the same time, utilizing a total internal reflection fluorescence microscope (TIRFM) to monitor alterations in the axon cytoskeleton and cell-ECM adhesion. Interestingly, it was observed that cortical neuron cells cultured on a poly-L- lysine (PLL) coated coverslip for 3 days retracted much faster than those cultured for 7 days, presumably because that stronger cell-substrate adhesion was formed after 7 days of culturing. Furthermore, a well-developed axon may not fully shrink back to the main cell body after the first axotomy. Instead, the retracting motion can be arrested/stopped. However, axon retraction will be re-triggered if a second transection is conducted. Finally, we showed that, in general, the retraction process can be divided into three stages: i) an initial stage with a high retracting speed of ~0.01 µm/s; ii) an adhesion-dominated stage with a shrinking velocity that is order of magnitude lower than the initial stage; and iii) the steady-state stage where no change in the axon length can be detected.

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