Momentum: Virginia Tech Mechanical Engineering Winter 2021 | Page 25

MOMENTUM • VIRGINIA TECH MECHANICAL ENGINEERING 25 well as improve techniques harnessing electroporation , like gene transfection , electrochemotherapy , and other cancer treatments .
In the study , Davalos and his graduate students in the Bioelectromechanical Systems Laboratory , engaged in in vitro electroporation , a method of administering electrical pulses to tissue to treat cancer . Electroporation was applied to numerous types of cells , including human glioblastoma and mesothelioma cells . Nain and his graduate students in the Spinneret based Tunable Engineered Parameters ( STEP ) Laboratory engaged in creating precisely controlled , suspended fibrous environments . This brought a unique perspective to electroporation , enabling careful observation of cellular mechanical response throughout the process .
In their experiments , the researchers were able to culture cells on suspended nanofibers , rather than on the flat bottom of a petri dish , which allowed them to mimic the native fibrous environment found inside the body . In Nain ’ s lab , researchers used nanonet force microscopy , a method pioneered by Nain , to measure cell forces . Cells attached to the nanonets and bent the flexible fibers , enabling the measurement of their contractile forces . In Davalos ’ lab , the nanonets were assembled in a custom microfluidic device housing two electrodes .
“ Cell properties and forces can be hard to understand intuitively ,” said Philip Graybill , a mechanical engineering doctoral student and first co-author on the study publication . “ How much force is a nanonewton anyway ? Other methods of characterization tend to be somewhat abstract , but in this study , the nanofibers provided a visually fascinating method to investigate cell behavior . Images of the nanofibers bending under the force of a cell brought these values to life .”
“ Cell forces have been studied before , to understand various biological phenomena , but never in the context of electroporation ,” added Aniket Jana , a mechanical engineering doctoral student and first co-author on the study . “ Our approach to monitor cell force dynamics provides a direct way of understanding the physical recovery mechanisms of cells following electric field treatments .”
The unique experimental setup led the team to their fundamental discovery . When high electric fields were applied , cellular forces decreased , which was concurrent with the formation of pores in the cell membrane . Cell force recovery coincided with membrane resealing , but the recovery showed an unusual biphasic response : increase and decrease in forces before the cells finally recovered their original contractility . Applying forces ( contractility ) is fundamental to the nature of cell . Cells exert this force , mediated by the cytoskeleton , to divide themselves , migrate , or heal wounds .
To the researchers , this biphasic response made it clear that cytoskeletal dynamics play a significant role in cell shape and force recovery .
Nain explained that cell membrane disruption is linked to the loss of contrac-
Top : Amrinder Nain , associate professor in mechanical engineering
Bottom : Rafael Davalos , professor in biomedical engineering and affiliate faculty in mechanical engineering