Johns Hopkins Biomedical Engineering faculty
Alexander A. Spector, PhD
Research Professor in Biomedical Engineering and Mechanical Engineering
Office: Traylor 411
Lab: Cell and Membrane Biomechanics Group
B.S., M.S., Engineering Mechanics, Moscow State University
Ph.D., Engineering Mechanics, Russian Adacemy of Sciences
The development of computational models enables better understandings of cell mechanics (electromechanics) and biophysics. Cell mechanical properties are now considered as fine indicators of pathological conditions — including the stage of a disease. Mechanical factors are also known to affect differentiation of stem cell. Electromechanical coupling is common to cells and cellular membranes, and it is critical to the performance of ion channels and molecular motors.
Our particular focus is hair cells in organs of hearing and balance. These cells sense sound or head acceleration via the stereocilia bundle by converting the mechanical input into current that changes cellular membrane potential (mechanoelectrical transduction). In addition to this, mammalian (human) cochleae have effector cells (outer hair cells) that provide active amplification and sharp frequency selectivity by generating an active force at the acoustic frequencies (electromechanical transduction). Our analysis is based on interconnected molecular-, cell-, and organ-level models. On the molecular-level, it is focused on two membrane proteins — prestin, in the somatic part of outer hair cells; and the mechanotransduction channel, in the tips of the stereocilia.
R.J. Powers, S. Roy, E. Atilgan, W.E. Brownell, S.X. Sun, P.G. Gillespie, and A.A. Spector. Stereocilia Membrane Deformation: Implications for the Gating Spring and Mechanotransduction Channel. Biophys. J. , 2012, 102, pp. 201–210.
S. Roy, W.E. Brownell, and A.A. Spector. Modeling Electrically Active Viscoelastic Membranes. PLoS ONE, 2012, 7, e37667.
K.R. Schumacher, A.S. Popel, B. Anvari, W.E. Brownell, and A.A. Spector. Computational Analysis of the Tether Pulling Experiment to Probe Plasma Membrane-Cytoskeleton Interaction in Cells. Physical Review E, 2009, 80, art. 041905.
S.X. Sun, B. Farrell, M.S. Chana, G. Oster, W.E. Brownell, and A.A. Spector. Voltage and Frequency Dependence of Prestin-Associated Electric Charge Transfer. Journal of Theoretical Biology, 2009, 260, pp. 137–144.
C.M. Nelson, R.P. Jean, J.L. Tan, W.F. Liu, N.J. Sniadecki, A.A. Spector, and C.S. Chen. Emerging patterns of growth controlled by multicellular form and mechanics. Proc. Natl. Acad. Sci. USA, 2005, 102, 11594–11599.
R.P. Jean, C.S. Chen, and A.A. Spector. Finite-element analysis of the adhesion-cytoskeleton-nucleus mechanotransduction pathway during endothelial cell rounding: Axisymmetric model. J. Biomech. Eng., 2005, 127, 594–600.