26 MOMENTUM • VIRGINIA TECH MECHANICAL ENGINEERING
SHOCKING THE CELLULAR WORLD ( CONTINUED )
Image of cell properties , displaying the mechanical force response ( left ) and the biphasic response of the cytoskeleton ( right ).
tility-bearing cytoskeleton inside the cell . He described the cytoskeleton as a dynamic and responsive meshwork ; its re-establishment is required for recovery of the cell ’ s contractility and shape .
“ It is remarkable how the cell cytoskeleton can fully recover within just a couple of hours , despite extensive damage caused by electric fields ,” Jana said . “ This shows the strong will of cells to live even after extreme perturbations . Such incredible cell adaptability in our suspended nanofibers further highlights how cancer cells can evade electric field treatments and still continue on metastasizing .”
“ It was amazing to see just how dynamic and responsive cells really are after electrical disruption ,” added Graybill . “ It was exciting to find that the loss of contractile force measured in one cell type also occurred in other cell types , because this suggested that this behavior is consistent across many cell types .
“ This was exciting , because a better understanding of cell recovery may improve techniques where cell recovery is desirable , such as in gene transfection , electrofusion , electrochemotherapy , or where cell recovery is undesirable , such as in cancer treatments , where it ’ s preferable for the cancerous cells to die .”
The researchers believe their new understanding of cell contraction and recovery has important implications for electroporation ’ s use in various applications , including molecular medicine , genetic engineering , and cellular biophysics . Nain said that the biphasic response they observed could enable the injection of larger particles into the cell , without having to use a higher electric voltage .
The cell membrane is like an insulator , and when you apply a voltage , the electrical pulse travels across the membrane , explained Davalos . At a critical voltage , pores form on the cell . The magnitude of the electric field controls whether or not pores will form in the membrane , while the various pulse parameters dictate the size of the particle that can be put into the cell .
Trying to increase those parameters could affect the particle size one can inject , but the higher the electrical voltage , the more likely the cell is to die . There is also a very narrow window where pores are open and able to receive materials before the cell reseals . The overall goal of electroporation is to disrupt the cell so that substances – such as medicine or DNA – can be injected into it . Identifying and understanding how long the disruption lasts is thus very important .
“ This shows the strength of collaboration across disciplines ,” Nain said . “ I knew about the electric field research by Davalos and wondered how we could integrate nanonet force microscopy , the cell force measurement platform developed in my lab , with