title: Mechanical stimulation of epithelial cells using polypyrrole microactuators.
abstract: The importance of mechanotransduction for physiological systems is becoming increasingly recognized. The effect of mechanical stimulation is well studied in organs and tissues, for instance by using flexible tissue culture substrates that can be stretched by external means. However, on the cellular and subcellular level, dedicated technology to apply appropriate mechanical stimuli is limited. Here we report an organic electronic microactuator chip for mechanical stimulation of single cells. These chips are manufactured on silicon wafers using traditional microfabrication and photolithography techniques. The active unit of the chip consists of the electroactive polymer polypyrrole that expands upon the application of a low potential. The fact that polypyrrole can be activated in physiological electrolytes makes it well suited as the active material in a microactuator chip for biomedical applications. Renal epithelial cells, which are responsive to mechanical stimuli and relevant from a physiological perspective, are cultured on top of the microactuator chip. The cells exhibit good adhesion and spread along the surface of the chip. After culturing, individual cells are mechanically stimulated by electrical addressing of the microactuator chip and the response to this stimulation is monitored as an increase in intracellular Ca(2+). This Ca(2+) response is caused by an autocrine ATP signalling pathway associated with mechanical stimulation of the cells. In conclusion, the present work demonstrates a microactuator chip based on an organic conjugated polymer, for mechanical stimulation of biological systems at the cellular and sub-cellular level.
authors.affiliation: Karolinska Institutet, Swedish Medical Nanoscience Center, Department of Neuroscience, SE-171 77 Stockholm, Sweden.
authors.forename: Karl
authors.initials: K
authors.lastname: Svennersten
authors.forename: Magnus
authors.initials: M
authors.lastname: Berggren
authors.forename: Agneta
authors.initials: A
authors.lastname: Richter-Dahlfors
authors.forename: Edwin W H
authors.initials: EW
authors.lastname: Jager
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001081:Apyrase / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D018929:Cell Culture Techniques / Q000295:instrumentation / Q000379:methods*; D004285:Dogs; D004566:Electrodes; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D011108:Polymers / Q000737:chemistry*; D011758:Pyrroles / Q000737:chemistry*; D013314:Stress, Mechanical
chemical_list: D011108:Polymers; D011758:Pyrroles; C067635:polypyrrole; D000255:Adenosine Triphosphate; D001081:Apyrase; D002118:Calcium