Adult human mesenchymal stem cell adhesion on optically transparent carbon s ubstrate modified with electrochemically-adsorbed protein

MADELEINE M. FARRER; TOMÁS E. BENAVIDEZ; MARISSA E. WECHSLER; CARLOS D. GARCIA; RENA BIZIOS

San Antonio, Texas

Conferencia; Annual Biomedical Research Conference for Minority Students (ABRCMS); 2014

Proteins adsorbed on material surfaces mediate and modulate subsequent interactions of anchoragedependent cells (i.e., those present in most mammalian tissues). Since cell adhesion and functions pertinent to new tissue formation are thus affected, understanding and controlling protein adsorption on material surfaces prior to subsequent cell interaction is critical for the success oftissue engineering and regeneration applications, but remain partially understood. The present research was motivated by this need and inspired by recent findings that applied electrical potential results in increased protein adsorption onto nanostructured carbon films. The hypothesis of this in vitro study was that substrate exposure to an electrochemical potential would promote adsorption of proteins, therefore providing conditions which modulate subsequent cell adhesion, a requirement for anchorage-dependent cell survival and function. For this purpose, rat-tail, Type I collagen (0.1 mg/mL in 20 mM acetic acid; pH 3.2) was adsorbed on the surface of optically-transparent carbon (OTC) using electrochemical adsorption under either 0.4 or 0.8 volts, at room temperature, for 3 hours. Subsequently, adult, human, mesenchymal stem cells (hMSCs) in hMSC basal medium (without serum) were seeded on the surface of each substrate and allowed to adhere in the absence of electrical potential, in a humidified, 37°C, 5% CO2/95% air environment for 2 hours. Then, the adherent cells were fixed, stained, visualized, and counted. The data of hMSC adhesion were expressed as cells/cm2 and compared to the respective controls. Controls were hMSCs seeded inparallel on either (1) tissue culture polystyrene (non-conductive substrate), (2) OTC without exposure to the electrical potential, or (3) pre-adsorbed protein on OTC without exposure to the electrical potential. The controls were maintained under similar conditions and analyzed using the aforementioned techniques. Increased hMSC adhesion was observed when Type I collagen was preadsorbed on OTC substrates under 0.8 volts. hMSC adhesion was similar on all OTC controls tested and on substrates with pre-adsorbed collagen under 0.4 volts of electric potential. The highest cell adhesion was on tissue culture polystyrene. The mechanisms underlying the electrochemical adsorption of proteins which direct subsequent cell adhesion on material surfaces need elucidation and are the subject of continuing research.