Label-free fast 3D coherent imaging reveals pancreatic islet micro-vascularization and dynamic blood flow

Abstract

In diabetes, pancreatic β-cells play a key role. These cells are clustered within structures called islets of Langerhans inside the pancreas and produce insulin, which is directly secreted into the blood stream. The dense vascularization of islets of Langerhans is critical for maintaining a proper regulation of blood glucose homeostasis and is known to be affected from the early stage of diabetes. The deep localization of these islets inside the pancreas in the abdominal cavity renders their in vivo visualization a challenging task. A fast label-free imaging method with high spatial resolution is required to study the vascular network of islets of Langerhans. Based on these requirements, we developed a label-free and three-dimensional imaging method for observing islets of Langerhans using extended-focus Fourier domain Optical Coherence Microscopy (xfOCM). In addition to structural imaging, this system provides threedimensional vascular network imaging and dynamic blood flow information within islets of Langerhans. We propose our method to deepen the understanding of the interconnection between diabetes and the evolution of the islet vascular network. GrapinBotton, and T. Lasser, "Combined optical coherence and fluorescence microscopy to assess dynamics and specificity of pancreatic beta-cell tracers," Sci. Rep. 5, 10385 (2015).

Development and Application of Optical Coherence Tomography (OCT)

“…Additionally, our group recently developed an en face matrix based approach of OCT, which allows to increase the penetration depth by a factor of two [172], and could be advantageous for in vivo experiments. Finally, we are now interested in the development of functional imaging in FF-OCT, in fresh tissues, or in living animals, either by measuring changes in the blood flow, similarly to what has been achieved in OCT [132,173], or by directly measuring changes in the tissue biomechanics, or cellular activity. We believe that diagnosis capabilities will further benefit from this research, since it might soon be possible not only to detect static structural changes in a tissue, but also to detect how it reacts to different stimuli, or different drugs.…”

“…Since the RNFL is damaged in glaucoma-the second leading cause of blindness worldwide [132]-and since RNFL birefringence is connected to layer integrity [133,134], the polarization properties of the RNFL were investigated as potential diagnostic markers for glaucoma. PS-OCT based assessment of the RNFL's birefringent properties might be particularly interesting since it was shown that polarization changes in experimental glaucoma can be observed earlier than RNFL thickness changes [135].…”

Self-assembly, buckling and density-invariant growth of three-dimensional vascular networks

“…Data and images from Ref. [30]. ponentially in time, or, in other words, linearly with the number of cells.…”

Full-Field Optical Coherence Tomography as a Diagnosis Tool: Recent Progress with Multimodal Imaging

“…Additionally, compared with dynamic OCT techniques [116,132], we take advantage of the higher spatial resolution to capture subcellular variations, which further enable the cells to be revealed. To our knowledge, the contrast revealed by D-FF-OCT is therefore quite unique.…”

“…Finally, we are now interested in the development of functional imaging in FF-OCT, in fresh tissues, or in living animals, either by measuring changes in the blood flow, similarly to what has been achieved in OCT [132,173], or by directly measuring changes in the tissue biomechanics, or cellular activity. We believe that diagnosis capabilities will further benefit from this research, since it might soon be possible not only to detect static structural changes in a tissue, but also to detect how it reacts to different stimuli, or different drugs.…”