Cell detachment in time. 1: control sample, 2:15 min. after treatment, 3: 1 hours after treatment, 4: 4 hours after tr

1. Cell detachment using electric discharge plasmas Ingrid E. Kieft, Eva Stoffels, Veronique Caubet-Hilloutou, Jos L.V. Broers, Frans C.S. Ramaekers, Dick W. Slaaf Department of Biomedical Engineering, Eindhoven University of Technology P.O.Box 513, 5600 MB Eindhoven, The Netherlands E-mail: I.E.Kieft@tue.nl • Introduction • Study of interaction of small atmospheric discharge with living cells • Use of novel plasma source the “plasma needle” [1] • Effects studied on both CHO K1 and human epithelial NSCLC MR65 cells • Exposed cells detach instantaneously from the surface • Loss of cell-cell interaction • Detached cells remain alive and reattach within several hours to surface • Plasma treatment can be performed with high precision with spot-sizes smaller than 1 mm • Neighbouring cells are left unaffected • Results and discussion • Treatment of cells with high dose can cause necrosis • If the right dose is applied, cells detach • A void can be created with dimensions sub-mm Treatment with high dose. Dead cells in red on top, then a void caused by detached cells, the green cells at the bottom are alive. Sharp boundaries! • Material and methods • Plasma generation • We ignite the RF plasma in helium. The frequency we use is about 13.2 MHz. • Plasma appears at the tip of a metal pin. It appears as a pink glow. • On the mechanism • Helium: inert, has largest heat conductivity of noble gases • Plasma temperature: below 30oC • Plasma influence expected from radicals and ions • Cells shielded from UV light by a PBS solution • Generated electric field not affecting cells • Cell detachment in time. 1: control sample, 2:15 min. after treatment, 3: 1 hours after treatment, 4: 4 hours after treatment. • Cells start attaching one hour after treatment • Same effect for fibroblasts and epithelial cells  cell detachment is general effect • Most likely cell adhesion molecules destroyed by plasma radicals [2] Plasma discharge Scheme of the experimental setup • Methods • Plasma parameters • Plasma power is 50 to 100 mW • Voltage peak to peak 200 - 400 V • Helium flow 2 l/min • Total irradiation time of sample is 1 minute • individual cells are irradiated for 5 to 10 seconds • Viability assays • PI and CTG are used to distinguish dead and living cells Proposed mechanism for detachment of cells. • Conclusions • Cells detach after plasma treatment, and remain alive. They are capable of reattachment and cytokinesis. • The plasma treatment can be performed with sub-millimetre precision. Neighbouring cells are not affected. • The high precision plasma treatment can have applications in wound healing and cancer treatment. References: [1] Stoffels, E., Flikweert, A.J., Stoffels, W.W., Kroesen, G.M.W., 2002, Plasma Sources Sci. Technol. 11: 383-388 [2] Stoffels,E., Kieft, I.E., Sladek, R.E.J., Superficial treatment of mammalian cells using plasma needle, accepted for publication in J.Phys.D: Appl. phys.