Rather than a mere storage site for triglycerides, it is now understood that adipose tissue (fat) is a complex, multicellular endocrine organ that has profound systemic effects, altering the function of nearly all other organ systems. Despite its importance, however, there is a lack of information on the dynamic nature of adipokine secretion and nutrient uptake in adipose tissue, highlighting several unmet needs in methodology. Few techniques exist to interrogate small amounts of adipose tissue, and there is a shortage of methods to explore dynamic function of the organ. Specifically, we have a limited view of the dynamic relationship between glucose, insulin, and adipose function, highlighting an immediate need for better in vitro techniques to study pancreas-adipose tissue crosstalk. As demonstrated in our previous funding period, we propose that our microfluidic systems are ideal to meet these ongoing needs. Our research team developed microfluidic approaches for culture of endocrine tissue, namely pancreatic islets and adipose tissue from C57BL/6J mice, as well as for sampling of hormone secretion. These systems permit dynamic interrogation of the tissues in ways not possible with standard techniques. The long-term goal of this research is to develop in vitro models of the endocrine system for applications in nutrition, metabolism, and drug discovery. In the short term, our objective is to develop a mouse-on-a-chip microfluidic system that permits dynamic and quantitative measurements of both hormone secretion and nutrient uptake from primary tissue. Microfluidic devices will be developed concurrently with small-volume methodology to assay secretion or nutrient uptake from pancreatic islets and adipose tissue, and 3D printing will be used to improve our novel device interfacing and tissue culture methods.
Aim 1 of the proposal seeks to develop an automated microfluidic input/output multiplexer (MUX) for generalizable dynamic control over hormones and nutrients to/from endocrine tissue.
Aim 2 will result in targeted small-volume compatible assays for hormones and free fatty acid uptake in adipose tissue.
Aims 3 and 4 are biological in nature, using the MUX system to determine the dynamics of hormone secretion, fatty acid uptake, and lipolysis in endocrine tissues with varied glycemic dynamics (Aim 3), and determining the role of dynamic feedback between the tissues using a co-culture MUX system (Aim 4). The rationale for this research to provide a flexibly programmable, in vitro micro-model of pancreas-adipose dynamics to test several important biological hypotheses related to gut-pancreas signaling dynamics, insulin/lipolysis/fatty acid uptake dynamics, and regulation of lipolysis at low insulin and glucos (fasting or ketogenic metabolism). The proposed work is significant as a first-of-its-kind in vitro mimic of pancreas-adipose physiology, which we expect will lead to better information on human dietary interventions. The proposal is thus innovative in its technological and its biological approaches. Preliminary evidence strongly supports the feasibility of these proposals, and the research team has a proven track-record of success.

Public Health Relevance

More than two-thirds of the US population is considered overweight or obese, and with diabetes incidence continuing to rise, studies have begun to reevaluate our standard dietary recommendations. Emerging evidence from diets low in carbohydrates has implicated a key role for insulin signaling, yet our view of the timing of insuli secretion and fat uptake into adipose tissue is limited. This project seeks to develop micro- scale methods to improve our understanding of this timing, work that is relevant to the mission of the NIDDK due to direct relevance to biochemistry and pharmacology of diabetes, obesity, and nutrition-related disorders.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK093810-05
Application #
9228365
Study Section
Instrumentation and Systems Development Study Section (ISD)
Program Officer
Haft, Carol R
Project Start
2011-09-01
Project End
2020-02-29
Budget Start
2017-03-01
Budget End
2018-02-28
Support Year
5
Fiscal Year
2017
Total Cost
$329,395
Indirect Cost
$104,395
Name
Auburn University at Auburn
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
066470972
City
Auburn University
State
AL
Country
United States
Zip Code
36849
Hu, Juan; Easley, Christopher J (2017) Homogeneous Assays of Second Messenger Signaling and Hormone Secretion Using Thermofluorimetric Methods That Minimize Calibration Burden. Anal Chem 89:8517-8523
Brooks, Jessica C; Judd, Robert L; Easley, Christopher J (2017) Culture and Sampling of Primary Adipose Tissue in Practical Microfluidic Systems. Methods Mol Biol 1566:185-201
Negou, Jean T; Avila, L Adriana; Li, Xiangpeng et al. (2017) Automated Microfluidic Droplet-Based Sample Chopper for Detection of Small Fluorescence Differences Using Lock-In Analysis. Anal Chem 89:6153-6159
Li, Xiangpeng; Brooks, Jessica C; Hu, Juan et al. (2017) 3D-templated, fully automated microfluidic input/output multiplexer for endocrine tissue culture and secretion sampling. Lab Chip 17:341-349
Kerscher, Petra; Turnbull, Irene C; Hodge, Alexander J et al. (2016) Direct hydrogel encapsulation of pluripotent stem cells enables ontomimetic differentiation and growth of engineered human heart tissues. Biomaterials 83:383-95
Brooks, Jessica C; Ford, Katarena I; Holder, Dylan H et al. (2016) Macro-to-micro interfacing to microfluidic channels using 3D-printed templates: application to time-resolved secretion sampling of endocrine tissue. Analyst 141:5714-5721
Maynard, B A; Brooks, J C; Hardy, E E et al. (2015) Synthesis, structural characterization, electronic spectroscopy, and microfluidic detection of Cu(+2) and UO2(+2) [di-tert-butyl-salphenazine] complexes. Dalton Trans 44:4428-30
Hu, Juan; Kim, Joonyul; Easley, Christopher J (2015) Quantifying Aptamer-Protein Binding via Thermofluorimetric Analysis. Anal Methods 7:7358-7362
Godwin, Leah A; Brooks, Jessica C; Hoepfner, Lauren D et al. (2015) A microfluidic interface for the culture and sampling of adiponectin from primary adipocytes. Analyst 140:1019-25
Kim, Joonyul; Hu, Juan; Bezerra, Andresa B et al. (2015) Protein quantification using controlled DNA melting transitions in bivalent probe assemblies. Anal Chem 87:9576-9

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