Targeted delivery of resveratrol to mouse white adipose tissue using adipose stromal cells (ASC) targeted nanoparticles

Background Obesity, a major public health problem, is characterized by increased white adipose tissue (WAT). Resveratrol (R), a polyphenolic compound, has a potential to increase beige cell formation if it is delivered to adipose stromal stem cells (ASC). Beige cells can increase energy expenditure via enhanced thermogenesis. Peptide CSWKYWFGEC has a high binding affinity to the cleavage product of decorin lacking the glycanation site (ΔDCN), serve as a functional receptor on the surface of ASC. We synthesized nanoparticles and incorporated the target peptide on the surface of nanoparticles to make ASC‐targeted nanoparticles (ATnano). Our hypotheses are that ATnano have high binding affinity to and uptake by ΔDCN‐expressing 3T3L1 mouse preadipocytes (ΔDCN‐3T3L1) ( in vitro ) and by mouse primary stromal vascular fraction (SVF) ( ex vivo ), and have high target specificity to mouse WAT depots ( in vivo ). This innovative approach enables targeted delivery of R to ASC for obesity treatment. Method Preparation of nanoparticles A lipid mixture composed of soy phosphatidylcholine, vitamin E acetate, Kolliphor HS15 and R with or without the peptide ligands were used to synthesize ATnano or NTnano, respectively. We replaced 2 mol% of total sPC with 18:1 Liss Rhod PE (810150 Avanti®, Rhoda) or DilC 18 (7) (D12731 Life®, DiR) to make Rhoda‐labeled or DiR‐labeled nanoparticles, respectively. Their particle size, polydispersity index (PI) and zeta potential were measured using a Brookhaven BI‐MAS particle size analyzer and ZetaPALS analyzer.In vitro binding and uptake of nanoparticles ΔDCN‐3T3L1 cells and primary SVF isolated from mouse WAT were cultured and treated with Rhoda‐labeled ATnano or NTnano at 4°C and 37°C for 2 hours. The target specificity of ATnano and NTnano to these cells were measured using an EVOS® fluorescence microscope. Primary gonadal SVF were treated with 10 μM of native R, R encapsulated ATnano (R‐ATnano) or R encapsulated NTnano (R‐NTnano) at 4°C and 37°C for 2 hours. The cellular R content was measured using a HPLC method.In vivo targeting of nanoparticles to WAT DiR‐labeled ATnano or NTnano were injected into obese C57BL/6J mice through tail veins. After 24‐hour, DiR fluorescence reflectance images of isolated brown fat and WAT depots were acquired in situ and after dissection using an IVIS® spectrum CT in vivo imaging system. SVF were isolated and cultured, and the DiR signals of these cells were obtained using the above microscope.Results The nanoparticle size was less than 100 nm. Their PI values were less than 0.3. ATnano compared to NTnano had a higher binding to and uptake by both ΔDCN‐3T3L1 cells and primary SVF. As compare to native R and R‐NTnano, R‐ATnano increased cellular R content in primary gonadal SVF. ATnano compared to NTnano had a higher target specificity to brown adipose tissue, retroperitoneal, inguinal and gonadal WAT. Importantly, cultured primary SVF isolated from the ATnano‐treated mice had higher cellular DiR signal intensity than SVF from NTnano‐treated mice. Conclusions ATnano target mouse WAT depots. Specifically, ATnano had higher binding affinity and capability to deliver more R to primary SVF than NTnano. Targeted delivery of R to ASC may enhance beige cell formation, subsequently increase thermogenesis, which portends a potential breakthrough in obesity treatment. Support or Funding Information Grant Funding Source: NIH 1R15AT008733‐01