Use of Vibrational Optical Coherence Tomography to Determine Mechanical Properties of Cells and Tissues in Vivo

The ability to measure the elastic and viscous mechanical properties of cells and tissues in vivo is important to understand the pathobiology of development, maturation, and diseases. Using vibrational optical coherence tomography (VOCT) my lab has developed a noninvasive technique to measure the elastic and viscous properties of cells, tissues, and implant materials both in vitro and in vivo. The results measured using VOCT suggest that the elastic modulus of isolated cells reported in vitro is much smaller than that of cells in series with other cells and extracellular matrix in vivo. At low strains the loss moduli of cells and tissues in vivo is strain rate dependent and decreases with increased strain rates above a strain rate of about 100 cycles/sec. The high viscous component of the mechanical behavior of soft tissues at low loading frequencies provides a physiologic mechanism to dissipate energy applied to soft tissues minimizing premature mechanical failure. Changes in elastic moduli exhibited by cells, blood vessels, and fibrous tissues can be followed during disease progression in vivo noninvasively. It is concluded that VOCT offers advantages over other methods for measuring mechanical properties of cells and tissues in vivo.