Ultrasound triggered topical supply of Bmp7 mRNA for white fats browning induction through engineered sensible exosomes | Journal of Nanobiotechnology


Cell tradition

HEK293T cells and RAW 264.7 cells have been cultured in full media containing excessive glucose Dulbecco’s modified Eagle medium (DMEM) (Hyclone, US) with 10% fetal bovine serum (Exocell, China) and 1% penicillin/streptomycin (Hyclone, US) in a humidified incubator with 5% CO2 at 37 °C.

Plasmid building

Bmp7 cDNA was synthesized in Genscript and subcloned into pWPI vector utilizing PacI and BstB1, with the resultant right clone designated as pWPI-Bmp7. All of the clones have been confirmed by sequencing and the suitable clones have been saved at − 80 °C for following software.


With a purpose to load Bmp7 mRNA into exosomes, HEK293T cells have been transfected with the corresponding plasmid with Lipofectamine 2000 (Invitrogen) following commonplace instruction. Briefly, tradition medium was changed with antibiotic-free DMEM medium when cell density grew to 60–70% in 100-mm tradition dish. Then, 20 µL Lipofectamine 2000 and 10 µg plasmid have been incubated individually in two centrifuge tubes containing 500 µL of DMEM medium at room temperature for five min. After that, contents of two centrifuge tubes have been combined and incubated at room temperature for 20 min. The above combination was added to HEK293T cell tradition dish talked about earlier than.

Exosome isolation and purification

The HEK293T cells have been used because the exosome donor cells on this examine. Cell tradition supernatants have been changed with serum-free medium a minimum of 48 h earlier than isolation course of. The supernatants have been collected and differentially centrifuged (250g for 10 min at 4 °C to remove useless cells and 10,000g for 15 min at 4 °C to take away residual mobile particles) adopted by filtration (0.22 μm filter; Milipore-Sigma, Bilicera, MA). Subsequent, the ensuing supernatant was centrifuged at 100,000g and 4 ℃ for two h to acquire the exosomes. Lastly, the extracted exosomes have been re-suspended in PBS and saved at − 80 °C earlier than utilizing.

Transmission electron microscopy

The morphology of remoted exosomes was analyzed by transmission electron microscopy. Briefly, the exosome suspension was added onto the copper mesh, then the exosomes have been stained with 2% uranyl acetate for 1 min and imaged by the electron microscope (JEM-2000EX TEM, JEOL Ltd, Tokyo, Japan).

Particle dimension evaluation

For measure the dimensions of distribution, the remoted exosomes have been diluted to 1 µg/mL and the measurement was carried out and analyzed utilizing NanoPlus (Otsuka Electronics, Japan). Measurements have been repeated a minimum of 3 times for every pattern.

Dedication of focus of exosomes by BCA technique

The focus of suspended exosomes was decided by whole protein focus. A small aliquot of exosomes was dissolved RIPA Lysis Buffer. Dedication of exosomal protein focus was carried out by Pierce BCA Protein Assay Equipment (Thermo, USA) beneath commonplace instruction [7,8,9].

Western blotting

Whole proteins from cells or exosomes have been extracted at 4 °C for 30 min by utilizing RIPA Lysis Buffer (Beyotime, China). Adipose tissue samples have been homogenized utilizing a Teflon/glass homogenizer in lysis buffer with pH 7.4, containing 50 mM Tris-HCL buffer, 250 mM NaCl, 5 mM EDTA, 0.1% Triton X-100, 50 mM NaF, 1 mM orthovanadate, and protease inhibitors. Then, the lysates have been centrifuged at 500g for 10 min at 4 °C and the supernatant was collected. Western blotting was carried out in line with the focus of proteins decided by BCA technique. Main antibodies used on this examine included anti-GM130 (1:1000, Abcam, ab30637), anti-CD63 (1:1000, Abcam, ab134045), anti-TSG101 (1:500, Santa, sc-7964), anti-CD9 (1:1000, Abcam, ab236630), anti-GAPDH (Proteintech, 60004-1-1 g) and anti-BMP7 (1:1000, Abcam, ab129156). Secondary antibodies have been HRP-conjugated goat anti-mouse IgG (D110087, BBI, China) and HRP-conjugated goat anti-rabbit IgG (1:5000, Cell Signaling Know-how, 7074P2).

Synthesis of CP05-TK-mPEG

About 100 mg of Maleimide-Thioketal-PEG2000 (Mal-TK-mPEG) have been dissolved in 5 mL N,N-dimethylformamide (DMF), then, 1.1 eq of the peptide CRHSQMTVTSRL (CP05) was added to the answer and incubated at room temperature for 12 h. After that, the combination was loaded into dialysis tubing with molecular reduce off at 3500 Da, and the dialyse in purified water for twenty-four h. Lastly, the dialysate was collected and the ultimate product CP05-TK-mPEG was obtained utilizing freeze-drying technique.

Development of SmartExo

Ce6 (diluted in DMSO, 30 mg/mL ) have been encapsulated into exosomes (1 µg/µL ) by way of electroporation. Then, Ce6 loaded exosomes have been remoted and resuspended with CP05-TK-mPEG options (1 mg CP05-TK-mPEG powder dissolved in 1 mL PBS) and incubated at 4 °C in a single day. The embellished exosomes have been remoted and washed twice utilizing PBS to take away residuals, and the merchandise have been resuspended in PBS as SmartExo.

Cel-miR-54 loading into exosomes

The cel-miR-54 (GenePharma, China) sequence is listed in Extra file 1: Desk S2. Exosomes have been loaded with cel-miR-54 by way of electroporation. Briefly, 100 µg exosomes have been combined with 0.5 OD cel-miR-54 mimics in 4 mm electroporation cuvette (BioRad, USA) and electroporated on Gene Pulser XcellTM Whole System (BioRad, USA) at 700 V/150 µF. After electroporation, the combination have been positioned on ice for a minimum of 30 min to recuperate the membrane.

In vitro tracing of exosomes

Exosomes (about 1 µg/µL of protein focus) have been labeled with DiI o by incubation with the dye (1 mM) on the ratio of 500:1 for 30 min in 37 °C darkish room, adopted by exosome isolation as described above. RAW 264.7 cells have been incubated with DiI-labeled exosomes for 4 h, 8 h, and 12 h. For these have been incubated with DiI-labeled SmartExo, ultrasound was utilized after 40 min of incubation. The ultrasound irradiation depth was set as 0.1 W/cm2 with an obligation cycle of 20%, and the irradiation time was 30 s (Extra file 1: Desk S1). The cells have been then washed with PBS for 3 times and stuck with 4% paraformaldehyde for 10 min and once more washed with PBS twice. Cell nuclei have been counter-stained with 1 µg/mL Hoechst 33,342 (Beyotime, China) diluted at 1:1000 for 10 min in 37 °C darkish room then washed with sodium acetate resolution to take away the nonspecific adhesion. The ready samples have been noticed and captured by Confocal Microscope (Eclipse C2, Nikon, Japan).

Animal experiments

Wholesome male C57/BL6J mice aged 8 weeks have been bought from Animal Heart of the Fourth Navy Medical College. The animal experimental and housing procedures have been carried out in accordance with the protocols of Animal Experimentation and Ethics Committee of Fourth Navy Medical College.

In vivo fluorescence tracing of exosomes

Exosomes (about 1 µg/µL of protein focus) have been labeled with DiI or DiR by incubation with the dye (1 mM) on the ratio of 500:1 for 30 min in 37 °C darkish room. Organ distribution evaluation of exosomes was carried out as beforehand described. Briefly, DiR-labeled exosomes have been washed with PBS to take away free dyes and tail-vein injected into mice. The dosages of exosomes remedy differ from examine to review, and 4 µg/g of exosomes per mouse for every time was chosen in our examine, which is analogous because the dose in revealed literatures [21]. For these have been injected with SmartExo, ultrasound was utilized on the belly space as soon as each hour within the first 6 h after injection. For in vivo experiments, the irradiation depth was set as 2 W/cm2, and the length was 180 s for every irradiation (Extra file 1: Desk S1). The distribution of exosomes in organs was detected 8 h after injection utilizing an IVIS Lumina II in vivo imaging system (PerkinElmer, Thermo Fisher, US).

For check of the sliced part, exosomes labeled with fluorescent dye DiI (Beyotime, China) have been administered into mice intravenously. Eight hours after the injection or ultrasound, the recent organs have been harvested, then washed with PBS and stuck in 4% paraformaldehyde for 30 min earlier than being embedded in optimum chopping temperature compound. Then, the embedded organs have been sliced into 10 μm sections on a freezing microtome (Leica, Germany). Tissue sections have been stained with 1 µg/mL Hoechst 33,342 (Beyotime, China) diluted at 1:1000 for 10 min then washed with PBS earlier than sealing with impartial gum beneath darkish circumstances. The ready samples have been noticed and captured by Confocal Microscope (Eclipse C2, Nikon, Japan) for exosomes monitoring.

Anti-obesity remedy

All mice have been fed with high-fat-diet and physique weights of mice have been monitored weekly. On the eighth week, mice fed a high-fat-diet developed weight problems (weighing a minimum of 20% greater than mice fed with regular chow food regimen). All animals have been randomly allotted to 4 teams (4 mice for every group) to begin remedies for weight problems as soon as three days for completely 3 weeks. The primary group was handled with physiological saline resolution (PBS), the second group was handled with pure exosomes (Exo, the third group was handled with Bmp7 loaded exosomes (Exo@Bmp7) and the final group was handled with Bmp7 loaded sensible exosome-based drug supply system (SmartExo@Bmp7). The dosage of exosomes in every group was decided as 4 µg/g per mouse as talked about above. Ultrasound irradiation was utilized on the belly space as soon as each hour within the first 6 h after injection for every group with a purpose to take away as a lot as PEG corona from SmartExo. The parameters have been set similar as described above (Extra file 1: Desk S1). All animals have been sacrificed after 3 weeks of remedies, and belly fats have been obtained to analysis the browning scenario.

RNA isolation and qRT-PCR

Whole RNA of the pattern was extracted utilizing TRIzol (Invitrogen, 15596018) adopted the usual directions. For mRNA, 2 µg of RNA was reverse transcribed into cDNA by SMART® MMLV Reverse Transcriptase (Takara). Whereas, for miRNA, 2 µg of RNA was reverse transcribed into cDNA utilizing miRcute Plus miRNA qPCR detection equipment (Tiangen). Experiment of qPCR was carried out with FastStart Important DNA Inexperienced Grasp Equipment (06924204001, Roche). Relative expression of mRNA and miRNA was respectively normalized to GAPDH/Gapdh and U6 ranges and calculated by 2−ΔΔCt. The PCR primer sequences are equipped in Extra file 1: Desk S2.


OAT have been excised and stuck in 10% formalin. Then they have been paraffin-embedded and sectioned previous to H&E staining or immunohistochemistry for Ucp1 (Abcam; 1:400) detection. Sign was detected utilizing the Vector ABC Elite equipment.

Statistical evaluation

Knowledge and outcomes are expressed as imply ± SEM as indicated. Pupil’s t-test was used for comparability between two teams (Graphpad Prism 7.0). P values of < 0.05 point out statistical distinction.


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