The challenge in cell physiology/pathology today is to translate in vitro findings to the living organism. We have developed a unique approach where signal-transduction can be investigated in vivo non-invasively, longitudinally at single cell resolution, using the anterior chamber of the eye as a natural body window for imaging. We will use this approach to understand how the universally important and highly complex signal Ca2+ is regulated in the pancreatic beta-cell, while localized in the vascularized and innervated islet of Langerhans, and how that affects the insulin secretory machinery in vivo. Engrafted islets in the eye take on identical innervation- and vascularization patterns as those in the pancreas and are proficient in regulating glucose homeostasis in the animal. Since the pancreatic islet constitutes a micro-organ, this imaging approach offers a seminal model system to understand Ca2+ signaling in individual cells at the organ level in real life. We will test the hypothesis that the Ca2+-signal has a key role in pancreatic beta-cell function and survival in vivo and that perturbation in the Ca2+-signal serves as a common denominator for beta-cell pathology associated with impaired glucose homeostasis and diabetes. Of special interest is how innervation impacts on Ca2+-dynamics and the integration of autocrine, paracrine and endocrine signals in fine-tuning the Ca2+-signal with regard to beta-cell function and survival. We aim to define key defects in the machinery regulating Ca2+-dynamics in association with the autoimmune reaction, inflammation and obesity eventually resulting in diabetes. Our imaging platform will be applied to clarify in vivo regulation of Ca2+-dynamics in both healthy and diabetic human beta-cells. To define novel drugable targets for treatment of diabetes, it is crucial to identify similarities and differences in the molecular machinery regulating the in vivo Ca2+-signal in the human and in the rodent beta-cell.