Differences in the biophysical properties of membrane and cytoplasm of apoptotic cells revealed using dielectrophoresis.
We have used dielectrophoresis to determine the dielectric properties of human chronic myelogeneous leukaemic (K562) cells during apoptosis (programmed cell death). Our results indicate that K562 cells increase markedly in cytoplasmic conductivity from 0.28 S/m to 0.50 S/m within the first 4 h following treatment with staurosporine, which then lasts beyond 12 h, whilst cell shrinkage increases the capacitance of the membrane from 9.7 mF/m2 to 20 mF/m2. After 24 and 48 h of incubation with staurosporine, multiple sub-populations were detected, highlighted by the dielectric changes that the cell undergoes before death. By comparing these results with those obtained by common apoptosis monitoring techniques Annexin V and TMRE (tetramethylrhodamine ethylester), it is possible to infer the role of ion efflux in the progress of apoptosis. The use of dielectrophoresis for monitoring apoptosis offers a number of benefits as it is both rapid and non-invasive. It can also be used in parallel with other assays in high-throughput screening applications.
Centre for Biomedical Engineering, School of Engineering, University of Surrey, Guildford, Surrey GU2 7XH, UK.
Fatima H
FH
Labeed
Helen M
HM
Coley
Michael P
MP
Hughes
D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis; D002462:Cell Membrane / Q000737:chemistry*; D003593:Cytoplasm / Q000737:chemistry*; D004553:Electric Conductivity; D004586:Electrophoresis / Q000379:methods*; D006801:Humans; D020014:K562 Cells; D009942:Organometallic Compounds; D019311:Staurosporine / Q000494:pharmacology
D017304:Annexin A5; D009942:Organometallic Compounds; C110932:tetramethyl rhodamine ethyl ester; D019311:Staurosporine