Airborne system in Type 2 diabetes studies : research focused on Langerhans islets

Abstract: The explosive increase in expansion of diabetes mellitus, particularly type 2 diabetes (T2D) is becoming a threat to public health which is associated with modern lifestyle, abundant nutrient supply, reduced physical activity, and obesity. It is realized that T2D only develops in insulin-resistance subjects which can start with β-cell dysfunction. In order to clarify the relationship between hormone release and metabolism in isolated pancreatic islets, the secretory effects of a non-fuel stimulator like acetylcholine was studied. The miniaturized "airborne system" (acoustic levitation and shooter) was combined with MALDI-MS to acquire data from single Langerhans islets and further β-cell metabolism. Levitation technique is a method which has been developed to study intra-and extra- cellular reactions at single or few cell levels. With this technique it is possible to handle 50 nl to 1500 nl sample volumes without contamination from solid walls. In combination with this method a CCD camera was used to check the islet in droplet during the experiments for surveillance of the droplet, for example it was possible to take pictures in different periods of time to calculate droplet size after evaporation to understand change in concentration by time. With usage of piezoelectric dispenser it was possible to keep size of droplet constant by time. MALDI-TOF mass spectrometry is a sensitive analytical technique with good limit of detection. In this work it was combined with airborne system (levitation technique) to analyze proteins/peptides that are released from Langerhans islets. α-cyano-4-hydroxy Cinnamic acid (CHCA) was used as matrix to crystallize the sample on MALDI plate. Samples were analyzed with MALDI-MS spectrometry. Spectra observed from mass spectrometry gave information about molecular mass, intensity and charge of the detected proteins and peptides.