Browning White Adipose Tissue for Diabetes Treatment

Project: Research project

Project Details

Description

This project is to develop a strategy of local and targeted delivery of trans-resveratrol (RES) containing nanoparticles (NPs) to subcutaneous adipose stromal stem cells (ASCs), aiming to induce browning of white adipose tissue (WAT), thereby, simultaneously reducing excess body fat and improving glycemic control. RES had a potential to induce browning of WAT, but its side toxicity and rapid hepatic catabolism, along with its low level of aqueous solubility and target specificity prevent the use of RES for WAT browning. We have successfully developed ASC-targeted RES-encapsulated nanoparticles (RES-NPs), which when administered intravenously, enhance RES delivery to ASCs and further increase the amount and activity of beige adipocytes, subsequently result in dramatic body fat and weight loss in a diet-induced obese mouse model. Even though ASC-targeted NPs had lower accumulation in the liver than non-targeted NPs, the liver still accumulated the majority of both ASC-targeted and non-targeted NPs when they were delivered intraveneously. This must be addressed. More critically, the fundamental mechnisms of WAT browning and the subsequent anti-diabete acitivities need to be studied. Therefore, in this project we propose to 1) subcutaneously inject ASC-targeted RES-NPs right above inguinal WAT for enhanced local delivery; 2) measure their binding and uptake by human and mouse adipose stromal cells, their target capacity and biodistribution in a diabetes mouse model (db/db mice); 3) determine the efficay and underlying mechanisms of WAT browning and anti-diabete activities in primary stromal cells isolated from db/db mice; 4) determine their anti-diabete activities and underlying mechanisms, and evaluate safety in db/db mice. We hypothesize that subcutaneous delivery of ASC-targeted RES-NPs can improve their ASC target capacity, enhance local WAT browning, further result in improved glucose homeostasis and insulin sensitivity and reduced body fat. This new approach will provide spatially-targeted and sustained delivery of RES to ASCs in subcutaneous WAT, thereby bypassing the liver and other tissues. This approach should minimize administration frequency, enhancing compliance, and most importantly, maximizing overall treatment efficacy while decreasing toxicity.
This project has following specific aims:
Aim #1: Determine ASC-targeted RES-NPs characteristics in vitro, and their biodistribution and target efficacy in db/db mice. The ASC-targeted RES-NPs will be synthesized using a sonication process. We will measure their characteristics including size, zeta potential, polydispersity, solubility and stability of RES and NPs, RES release study, and physicochemical characterization. The binding and uptake of RES-NPs by human adipose stromal cells will be determined in an ex vivo experiment. RES-NPs biodistribution will be measured using an IVIS imaging system. The ASC target capacity in stromal vascular fractions isolate from mouse subcutaneous and other adipose depots will be quantified using flow cytometry.
Aim #2: Determine the efficacy by which ASC-targeted RES-NPs induces browning and improves insulin signaling in primary stromal cells derived from the db/db mouse. ASCs from db/db mice will be treated with non-targeted or ASC-targeted RES-NPs. Cell differentiation, browning effects, glucose uptake, insulin sensitivity and inflammation in those cells will be determined. The underlying mechanisms of WAT browning, glucose uptake and insulin signaling pathway will be determined using real-time PCR, Western blot, nuclear receptor knockdown and transactivational assays.
Aim #3: Determine anti-diabetic effects and safety of ASC-targeted RES-NPs in db/db mice. Body composition, WAT histological and immunohistochemistry assay will be used to confirm browning of WAT. Insulin, glucose and pyruvate tolerance tests, and euglycemic-hyperinsulinemic clamps will be conducted to determine therapeutic effects of WAT browning via subcutaneous delivery of ASC-targeted NPs on diabetes in db/db mice. Concentrations of RES, lipids and inflammatory factors in blood, liver, skeletal muscle, adipose tissues will be measured. The underlying mechanisms of anti-diabetic activities in tissues will be studied using real-time PCR, Western blot, and immunohistochemistry methods. To evaluate safety, we will perform complete necropsies, blood tests, and routine histological examinations of the liver, heart, aorta, kidneys, skeletal muscle, spleen, lungs, and brain.
In summary: Previous studies have shown that browning of WAT leads to metabolic benefits. Proof of concept approaches such as cold acclimation induce beige adipocyte formation, but lack practical utility. RES is capable of inducing WAT browning, but has low efficacy and other limitations, which we addressed by developing ASC-targeted RES-NPs administered intravenously. This proposal will further enhance the delivery of RES-NP for inducing WAT browning by local subcutaneous injection near WAT. The outcomes of this project will establish bases for further study, by leveraging NIH R01 funds, towards to ultimate human applications. This project will strengthen student education and boost research at Texas Tech University.
StatusActive
Effective start/end date6/1/205/31/22

Funding

  • HHS: National Institutes of Health (NIH): $171,005.00

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