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An improved protocol for optical projection tomography imaging reveals lobular heterogeneities in pancreatic islet and β-cell mass distribution
Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
2011 (English)In: Islets, ISSN 1938-2014, Vol. 3, no 4, 204-208 p.Article in journal (Refereed) Published
Abstract [en]

Optical projection tomography (OPT) imaging is a powerful tool for three-dimensional imaging of gene and protein distribution patterns in biomedical specimens. We have previously demonstrated the possibility, by this technique, to extract information of the spatial and quantitative distribution of the islets of Langerhans in the intact mouse pancreas. In order to further increase the sensitivity of OPT imaging for this type of assessment, we have developed a protocol implementing a computational statistical approach: contrast limited adaptive histogram equalization (CLAHE). We demonstrate that this protocol significantly increases the sensitivity of OPT imaging for islet detection, helps preserve islet morphology and diminish subjectivity in thresholding for tomographic reconstruction. When applied to studies of the pancreas from healthy C57BL/6 mice, our data reveal that, at least in this strain, the pancreas harbors substantially more islets than has previously been reported. Further, we provide evidence that the gastric, duodenal and splenic lobes of the pancreas display dramatic differences in total and relative islet and β-cell mass distribution. This includes a 75% higher islet density in the gastric lobe as compared to the splenic lobe and a higher relative volume of insulin producing cells in the duodenal lobe as compared to the other lobes. Altogether, our data show that CLAHE substantially improves OPT based assessments of the islets of Langerhans and that lobular origin must be taken into careful consideration in quantitative and spatial assessments of the pancreas.

Place, publisher, year, edition, pages
Austin: Landes Bioscience , 2011. Vol. 3, no 4, 204-208 p.
Keyword [en]
Animals, Cell Size, Computational Biology/*methods, Female, Image, Enhancement/methods, Imaging, Three-Dimensional/methods, Insulin-Secreting Cells/*cytology, Islets of Langerhans/*anatomy & histology, Mice, Mice, Inbred C57BL, Organ Size, Pancreas/anatomy & histology, Pancreas, Exocrine/anatomy & histology, Reproducibility of Results, Tomography, Optical/*methods
National Category
Endocrinology and Diabetes
Research subject
Molecular Medicine
Identifiers
URN: urn:nbn:se:umu:diva-50597DOI: 10.4161/isl.3.4.16417PubMedID: 21633198OAI: oai:DiVA.org:umu-50597DiVA: diva2:465723
Available from: 2011-12-15 Created: 2011-12-15 Last updated: 2011-12-22Bibliographically approved
In thesis
1. Imaging the pancreas: new aspects on lobular development and adult constitution
Open this publication in new window or tab >>Imaging the pancreas: new aspects on lobular development and adult constitution
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The mouse pancreas is a mixed exocrine and endocrine glandconsisting of three lobular compartments: the splenic, duodenal and gastric lobes. During embryogenesis, the pancreas forms from two progenitor populations located on the dorsal and ventral side of the primitive gut tube. These anlagen are brought in close proximity as the gut elongates and rotates, and fuse to form a single organ. The splenic and duodenal lobes develop from the dorsal and ventral anlagen, respectively.

In the adult pancreas, exocrine tissue secretes digestive enzymes intothe gut lumen to support nutrient uptake. The endocrine Islets of Langerhans are scattered throughout the exocrine tissue and aid in regulation of energy homeostasis through the secretion of hormones. One of the key players in energy homeostasis is the pancreatic ß-cell, which is the most abundant cell type of the islets. The β-cells regulates blood glucose levels through the action of insulin. Conditions where this regulation does not function properly are gathered under the common name of Diabetes mellitus.

Type 1 diabetes (T1D) is characterized by insulin deficiency due to autoimmune destruction of the ß-cells. Using recently developed protocols for optical projection tomography (OPT) whole-organ imaging, we have revealed new spatial and quantitative aspects on ß-cell mass dynamics and immune infiltration during the course of T1D development in the non-obese diabetic (NOD) mouse model. We show that although immune infiltration appears to occur asynchronously throughout the organ, smaller islets, mainly located in the periphery of the organ, preferentially loose their ß-cells during early stages of disease progression. Larger islets appear more resistant to the autoimmune attack and our data indicate the existence of a compensatory proliferative capacity within these islets. We also report the appearance of structures resembling tertiary lymphoid organs (TLOs) in association with the remaining islets during later phases of T1D progression.

OPT has already proven to be a useful tool for assessments of ß-cellmass in the adult mouse pancreas. However, as with other techniques, previous protocols have relied on a tedious degree of manual postivacquisition editing. To further refine OPT-based assessment of pancreatic ß-cell mass distribution in the murine pancreas, we implemented a computational statistical approach, Contrast-Limited Adaptive Histogram Normalisation (CLAHE), to the OPT projection data of pancreata from C57Bl/6 mice. This methodology provided increased islet detection sensitivity, improved islet morphology and diminished subjectivity in thresholding for reconstruction and quantification. Using this approach, we could report a substantially higher number of islets than previously described for this strain and provide evidence of significant differences in islet mass distribution between the pancreatic lobes. The gastric lobe stood out in particular and contained a 75% higher islet density as compared to the splenic lobe.

Although the development of the early pancreatic buds has been relatively well studied, later morphogenetic events are less clear and information regarding the formation of the gastric lobe has largely been missing. Using OPT we have generated a quantitative three-dimensional road map of pancreatic morphogenesis in the mouse. We show that the gastric lobe forms as a perpendicular outgrowth fromthe stem of the dorsal pancreas at around embryonic day (e) 13.5, which grows into a mesenchymal domain overlaying the pyloric sphincter and proximal part of the glandular stomach. By analyzing mutant mice with aberrant spleen development, we further demonstrate that proper formation of the gastric lobe is dependent on the initial formation of the closely positioned spleen, indicating a close interplay between pancreatic and splenic mesenchyme during development. Additionally, we show that the expression profile of markers for pancreatic multipotent progenitors within the pancreas is heterogenous with regards to lobular origin. Altogether, our studies regarding the morphogenesis and adult constitution of the mouse pancreas recognize lobular heterogeneities that add important information for future interpretations of this organ.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2011. 50 p.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 1471
Keyword
Type 1 diabetes, ß-cell mass, tertiary lymphoid organs, biomedical imaging, optical projection tomography, morphogenesis, pancreas development, gastric lobe, spleen development.
National Category
Other Basic Medicine Medical Genetics
Research subject
Medical Genetics; Developmental Neurosciences; Molecular Medicine
Identifiers
urn:nbn:se:umu:diva-50601 (URN)978-91-7459-341-9 (ISBN)
Public defence
2012-01-20, Betula, Analysvägen 1, By 6M, Vån 1, Umeå, 09:00 (English)
Opponent
Supervisors
Available from: 2011-12-22 Created: 2011-12-15 Last updated: 2011-12-22Bibliographically approved

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