Nanoparticle-mediated selective Sfrp-1 silencing enhances bone density in osteoporotic mice | Journal of Nanobiotechnology








Poly(D,L-lactide-co-glycolide) (Resomer® RG502H, Mw 7000–17,000) was bought from Evonik (Germany), Soy L-α-phosphatidylcholine (95%) (PC) was obtained from Avanti Polar Lipids (USA), DSPE-mPEG(2000) (1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)] and DSPE-PEG(2000)-Maleimide (1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[maleimide(polyethylene glycol)-2000] had been supplied by Nanosoft Polymers (USA). DOTAP (1,2-dioleoyl-3-trimethylammonium-propane) (Mw 774.19), protamine sulfate (Mw 5000–10,000), Tris (2-carboxyethyl) phosphine hydrochloride (TCEP) (Mw 286.65) and coumarin-6 (Mw 350.25) had been bought from Sigma-Aldrich (USA). The particular GapmeR to silence the gene expression of SFRP1 (5′-GGTCAGTAACTAAGTT- 3′) and the management GapmeR with out therapeutical exercise (5′- AACACGTCTATACGC- 3′) labelled or not at 5′ with FAM had been bought and designed by Quiagen (Germany). The particular aptamer for murine bone marrow mesenchymal stem cells (mMSC) (5′-GAATTCAGTCGGACAGCGACGACGGTGATATGTCAAGGTCGTATGCACGAGTCAGAGGGATGGACGAATATCGTCTCCC-3′) was supplied by Built-in DNA Applied sciences (USA).

Lipid-polymer hybrid nanoparticles synthesis and characterization

Synthesis process: modified nanoprecipitation methodology

Totally different LPNPs formulations had been ready to check the pH impact on the LPNPs physicochemical properties. LPNPs of variable shell composition had been obtained by modifying their lipid elements whereas retaining all of the remaining variables fixed resulting in 4 LPNPs formulations with the next lipid composition: (1) DOTAP; (2) DSPE-mPEG2000; (3) PC + DSPE-mPEG2000 and (4) DOTAP + PC + DSPE-mPEG2000. LPNPs had been developed by a modified single-step nanoprecipitation methodology equally to beforehand described [30]. Briefly, 1.32 µg of GapmeR (26.4 µg/mL) was incubated with protamine sulfate (0.9 mg/mL) for 40 min at room temperature earlier than NPs preparation. Then, 50 µL of the GapmeR + protamine resolution was added to the natural section fashioned by PLGA (5 mg/mL) or PLGA (5 mg/mL) + DOTAP (0.3 mg/mL) when required in 1 mL of acetone and blended. This combination was poured in 10 mL of 4% EtOH in water containing DSPE-mPEG2000 (0.0637 mg/mL) alone or with PC (0.02 mg/mL) beforehand dissolved at 65 °C [31] (aqueous section). NPs had been stored beneath fixed magnetic stirring for 1 h to evaporate the solvent. After solvent removing, LPNPs had been concentrated to a ultimate quantity of 400 µL by ultrafiltration utilizing Amicon filters (Amicon®Extremely 100 kDa, Merck Millipore, Eire) at 10,000 rpm for 10 min. The obtained nanoparticles had been characterised at native pH in water and diluted in phosphate buffer at pH 5.4, 6.0, 7.0 or 7.4.

For aptamer conjugation, DSPE-PEG2000-maleimide was added to the aqueous section changing a part of the DSPE-mPEG2000 as beforehand proven [29]. Alternatively, fluorescently labelled nanoparticles had been obtained by including coumarin-6 at 4 µg/mL to the natural section.

Dynamic mild scattering (DLS)

All LPNPs batches had been characterised when it comes to common diameter, polydispersity index (PdI), and zeta-potential (ζ-potential) by dynamic mild scattering utilizing a Zetasizer Nano (Malvern). All measurements had been made in triplicate. Earlier than characterization, samples had been appropriately diluted with MilliQ-water (1:10) and sonicated in a water tub for 1 min.

Transmission electron microscopy (TEM)

LPNPs had been morphologically characterised by transmission electron microscopy (TEM). Samples (10 µL) had been deposited on carbon membrane coated cooper grids and stained with a 2% w/v phosphotungstic acid resolution for two min. LPNPs morphology was assessed utilizing the JEM 2010 electron microscope (JEOL, Japan).

LPNPs floor modification utilizing a murine mesenchymal stem cells particular aptamer

The floor functionalization of LPNPs with a murine mesenchymal stem cells (mMSC) particular aptamer was carried out as already reported [29]. Briefly, NPs suspensions obtained as described in “Synthesis process: modified nanoprecipitation methodology” part. had been buffered with 5X phosphate buffer to get a ultimate pH of seven.4 and incubated with thiol-reactive aptamer for 1 h at room temperature. To acquire the thiol-reactive aptamer the industrial SS-modified aptamer was diminished to aptamer-SH by its incubation with a 100-fold extra of (tris(2-carboxyethyl)phosphine) (TCEP) for two h at room temperature. The ultimate aptamer:maleimide molar ratio used for response was 0.01:1. Functionalized LPNPs had been characterised when it comes to common diameter, zeta-potential and PdI.

The aptamer conjugation effectivity was measured utilizing FAM-modified aptamer. The non-associated aptamer was quantified after NPs ultrafiltration (Amicon®Extremely filters 100 kDa, 10.000 rpm for 10 min) utilizing a plate reader (Biotek, USA) at 485/528 nm.

Oligonucleotide encapsulation effectivity and launch

Oligonucleotide encapsulation effectivity (EE) and launch profile had been evaluated utilizing fluorescently labelled GapmeR. To evaluate the NPs EE, the non-encapsulated GapmeR was quantified at 485/528 nm after LPNPs preparation and ultrafiltration as described above. The quantity of GapmeR launched throughout aptamer conjugation was additionally measured following the identical process.

$$EE left(%proper)= frac{Whole, GapmeR-Free, GapmeR}{Whole, GapmeR} occasions 100,$$

the place free GapmeR is the quantity of the non-incorporated oligonucleotide throughout LPNPs preparation or functionalization procedures, respectively.

Moreover, in vitro GapmeR launch assays had been carried out diluting the loaded LPNPs with DEPC water and incubating the resultant suspensions at 4 °C or 37 °C. At completely different time factors, samples had been ultrafiltrated (Amicon®Extremely filters 100 kDa, 10,000 rpm for 10 min) and the free GapmeR was quantified at 485/528 nm within the filtrated resolution. The assay was carried out by triplicate.

Nanoparticle’s cytotoxicity, cell uptake and intracellular location

LPNPs cytotoxicity was studied in major mMSC and macrophages (Uncooked 264.7 ATTC, USA). mMSC had been remoted from FVB mice as beforehand described [32]. Cells had been seeded at 20,000 cells per properly on 96-well plates with full tradition media (DMEM + 10% Bovine Fetal Serum (FBS), 1% Penicillin/streptomycin and 1% L-Glutamine) and allowed to connect for twenty-four h. Afterwards, cell monolayers had been incubated for twenty-four h with bare or aptamer-functionalized LPNPs suspensions in DMEM at variable concentrations (0.1 µg/mL–1.41 mg/mL). Cell viability was measured by an XTT assay (Roche) following the producer’s directions. All exams had been carried out by triplicate.

To evaluate LPNPs cell uptake, fluorescently labelled nanoparticles had been used. mMSCs had been seeded on the similar density as described above for the cytotoxicity exams in 24-well plates and incubated with the completely different nanoparticles’ suspensions for two h. Then, the medium was eliminated, the cells had been washed twice with DPBS and tripsinized at 37 °C and 5% CO2 for five min, the cells suspension was then centrifugated at 2100 rpm for 4 min and cells had been analyzed with the Tali® Picture-Based mostly Cytometer (Thermofisher). The share of cell uptake was obtained by counting each the cells stained with coumarin-6 and whole cells. The flexibility of the aptamer conjugation to particularly improve NPs uptake in MSCs was additionally assessed. To this finish, NPs uptake was quantified as beforehand revealed by our group in murine MSC cell line C3H10T1/2 and fibroblasts (BALB/3T3 clone A31, ATTC, USA) cultured within the above talked about full tradition media [33]. Briefly, cells had been seeded on the similar density as earlier experiments in 96-well plates and allowed to connect for 18 h. Afterwards, NPs suspensions had been added to every properly and fluorescence was measured utilizing a microplate reader (Bio Tek). Cell monolayers had been then incubated for two h with the NPs and subsequently washed thrice with DPBS to take away non-internalized NPs. Lastly, cells had been lysed with Triton X-100 1% and the fluorescence of the lysates was measured. Relative NPs uptake was obtained dividing the clean corrected lysates fluorescence by the clean corrected preliminary fluorescence. Alternatively, NPs uptake was visualized by fluorescence microscopy and transmission electron microscopy. For the fluorescence microscopy cells had been seeded on the similar density as described above in a tradition slide (Falcon®, CultureSlides) and handled with the LPNPs suspensions for two h, washed twice with DPBS and glued with 4% paraformaldehyde for two h at room temperature. Afterwards, cells had been washed twice with DPBS and permeabilized with 0.1% Triton X-100 for 15 min, adopted by two washes with DPBS and an incubation with 50 µg/mL rhodamine phalloidin (Thermo Fisher Scientific, USA) for 40 min. Then, wells had been washed twice and incubated with 1 µg/mL of DAPI for five min. Lastly, cells had been visualized utilizing a fluorescence microscope EVOS M5000 Imaging System (ThermoFisher). The internalization pathway adopted by the LPNPs was evaluated by transmission electron microscopy. Cells had been seeded on the similar density as beforehand described on Petri dishes and handled for two h with the nanoparticle’s suspensions. Cells had been mounted in 3% glutaraldehyde in phosphate buffer (0.12 M Na2HPO4 and 0.12 M NaH2PO4; pH 7.2) for 60 min at room temperature. Then they had been scraped off from the dishes, transferred to a 1.5 mL tube, and sequentially centrifuged at 7000 rpm and 12,000 rpm for 10 min. Fastidiously, samples had been washed with 0.12 M phosphate buffer with out disturbing the pellet, and additional mounted in 1% OsO4 for 3 hours beneath delicate agitation. The cell pellet was dehydrated in elevated acetone concentrations and embedded in Araldite (Durcupan, Fluka, Switzerland). Ultrathin sections mounted in copper grids had been stained with lead citrate and uranyl acetate and examined with a JEOL 2011 electron microscope operated at 80 kV.

In vitro NPs gene silencing effectivity utilizing major mMSC and immortalized cell strains (C3H10T1/2)

The in vitro SFRP1 silencing effectivity of GapmeR-loaded NPs functionalized or not with an mMSC-specific aptamer was assessed utilizing each murine major MSC (mMSC) and an the immortalized murine MSC line C3H10T1/2. Cells had been cultured with full tradition media (DMEM + 10% FBS + 1% P/S) and tripsinized when reaching a confluence of 70%. Main cells had been used at passage 2. Cells had been seeded on 24-well plates at a density of 25,000 cells per properly and let to connect in a single day. Two hours earlier than the transfection, cell tradition media was eliminated and cell monolayers had been washed with DPBS (Lonza) adopted by the addition of the correspondent remedies in basal cell tradition media (Opti-MEM, Life Applied sciences Inc., Gaithersburg, MD) with out supplementation. Cell monolayers had been handled with 400 µL of the next circumstances: (1) No therapy (basal media); (2) Management GapmeR beforehand complexed with the transfection reagent Dharmafect (20 nM) (Cntrl); (3) Management GapmeR encapsulated in unfuntionalized NPs (equal GapmeR focus 20 nM) (LPNPs-Cntrl); (4) SFRP1 silencing GapmeR beforehand complexed with the transfection reagent Dharmafect (20 nM) (SFRP1); (5) SFRP1 silencing GapmeR encapsulated in unfuntionalized NPs (equal GapmeR focus 20 nM) (LPNPs-SFRP1) and (6) SFRP1 silencing GapmeR encapsulated in aptamer funtionalized NPs (equal GapmeR focus 20 nM) (Apt-LPNPs-SFRP1) cells had been stored in commonplace cell tradition circumstances (37 °C, 5% CO2). GapmeR-Dharmafect complexes had been obtained following commonplace protocols [Dharmafect (Dharmacon, Horizon Discovery, Cambridge, UK)]. Briefly, each GapmeR and Dharmafect had been diluted to the specified focus in basal cell tradition media and incubated 5 min at room temperature. Afterwards, the GapmeR resolution was drop-wise added to the Dharmafect resolution and the combination was allowed to accept 20 min at room temperature then, complexes had been added to the cell monolayers.

After 24 h of therapy an equal quantity of full media was added to the wells and at 48 h post-treatment mRNA was remoted from cell cultures. To this finish, cells had been washed twice with PBS and picked up with Trizol by scrapping. RNA was extracted by the phenol–chloroform approach. RNA reverse transcription was carried out with the PrimeScript RT reagent package (RR037A, Takara Bio Inc, Shiga, Japan) in accordance with the producer’s protocol. For the gene expression measurements, an actual time quantitative PCR was carried out utilizing Taqman assay (Thermo Fisher Scientific).

Gene silencing was examined utilizing Mm00489161_m1 (Sfrp1) Taqman assay. Housekeeping genes GAPDH (Assay Mm99999915_G1) and RPL13A (Assay Mm0162986_gH) had been used for normalization.

LPNPs biodistribution

Animal experiments had been carried out in accordance with the European Union laws on Care and Use of Animals in Experimental Procedures (2010/63/UE) and after approval by the Ethic Committee for animal care of College of La Laguna (CEIBA2018-0310).

Biodistribution experiments had been carried out with each bare LPNPs (99mTc-LPNPs) and LPNPs functionalized with the aptamer (99mTc-Apt-LPNPs) utilizing two teams of 12 animals. The nanoparticle suspension (50 µL at 3 mg/mL) was injected within the tail vein of every mice beneath fasted circumstances. At prefixed occasions (1, 4 and 14 h) 4 mice of every group had been euthanized. Blood samples had been collected (by cardiac puncture) and the center, liver, lungs, kidneys, spleen, thyroid, mind, femur, tibia, hip, ribs and cranium, had been eliminated. Organ and blood related exercise was counted utilizing a gamma counter (Packard, Cobra II). Outcomes are expressed as the proportion of the entire administered dose per gram of tissue.

LPNPs had been labelled with 99mTc utilizing SnCl2 H2O as decreasing agent and ascorbic acid as antioxidant, beneath nitrogen environment. The labelling was carried out including 1–1.5 mCi of 99mTcO4Na in saline resolution to 0.85 mL of the LPNPs suspension (3.6 mg/mL) [34]. The suspension was shaken for 10 min at 150 rpm and the labelled suspension was buffered to a pH of seven.2–7.4 with 150 µL of NaHCO3 (0.5 M). The labelling effectivity was assessed by on the spot skinny layer chromatography (iTLC) utilizing silica gel-coated strips (Varian Iberica, S.L.) with acetone because the cellular section. The labelling effectivity was quantified by counting the radioactivity within the two equal halves of the strip utilizing a gamma counter (Packard, Cobra II). Free 99mTcO4 migrates to the entrance whereas radiolabeled LPNPs remained on the dripped level. Radiolabeling effectivity was additionally confirmed by filtration utilizing Amicon centrifugal filters (Amicon®Extremely filters MWCO 100 kDa). Free radioactivity within the filtrate was measured. The radiolabeling stability of the formulations was checked over a interval of 24 h by iTLC, as described above.

In vivo osteoinduction capability of Apt-LPNPs-SRFP1

To judge the in vivo impact of the developed LPNPs within the bone tissue of osteoporotic mice 18 feminine 16-week-old FVB mice had been used on this examine. The osteoporosis mannequin was carried out as beforehand described [32] by bilateral ovariectomy (OVX) mixed with subcutaneous administration of three mg/kg dexamethasone 21-isonicotinata (DEX) (Deyanil Retard, Fatro Ibérica, Spain) each week for 3 months. The osteoporotic-like bone situation was beforehand validated [32].

After three months, animals had been divided in three teams and handled with 50 µL per thirty days by intravenous administration through tail with one of many following remedies: (1) physiological saline resolution (Management); (2) Apt-LPNPs-Cntrl 3 mg/mL or (3) Apt-LPNPs-SFRP1 3 mg/mL. The stablished GapmeR dose was in all instances 25 ng. Animals had been monitored by densitometry (PIXImus, GE Lunar, USA) beneath isofluorane anesthesia the day earlier than every dose administration and euthanasia (0, 1, 2 and three months) [32]. At three months, mice had been euthanized by perfusion fixation beneath anesthesia [35] and bones and organs had been extracted for histological and immunohistochemistry assessments.

Histological and histomorphometric and analyses

To find out the impact of gene silencing on osteoporotic bone construction and microarchitecture, the femurs had been extracted and ready for histological evaluation as beforehand described [36]. Briefly, samples had been mounted in 4% paraformaldehyde resolution, decalcified in Histofix® Decalcifier (Panreac, Barcelona, Spain) and embedded in Paraplast®. Longitudinal sections of 5 µm thick had been obtained from every of the femurs with a microtome (Shandon Finesse 325). The sections had been stained with hematoxylin-erythrosine for bone construction analysis. Whereas bone mineralization was assessed with VOF trichrome stain, through which red-brown staining signifies superior mineralization, whereas much less mineralized, newly fashioned bone stains blue [37]. The histomorphometric evaluation was carried out by measuring the next parameters: thickness of the cortical bone (Ct.Wi) and quantity (Tb.N), width (Tb.Wi) and separation (Tb.Sp) of the trabeculae in trabecular bone. Sections had been analyzed by mild microscopy (LEICA DM 4000B) and computer-based picture evaluation software program (Leica Q-win V3 Professional-Picture Evaluation System, Barcelona, Spain) was used to judge the above talked about histomorphometrical parameters. On this examine, the histomorphometric parameters have been evaluated in 2D as direct indexes, utilizing 5 µm thick longitudinal sections all through the whole femur. Between 8 and 12 sections per animal had been evaluated. The variety of trabeculae (Tb.N) was decided, contemplating completely different trabeculae these in several instructions or orientations. Trabecular separation (Tb.Sp), outlined as the gap between the borders of the trabeculae. Trabecular thickness (Tb.Wi) and cortical bone thickness (Ct.Wi), as the gap between the perimeters in every of those buildings, measured at completely different factors alongside them. The measurements of the structural parameters of the cancellous bone (Tb.N, Tb.Sp and Tb.Wi) had been made in cancellous bone of each epiphyseal areas and, the structural measurements of the cortical bone (Ct.Wi) had been made in each, epiphyseal and diaphyseal bone areas.

Immunohistochemistry analyses

The expression of collagen kind I (Col I), an early osteogenesis marker, and osteocalcin (OCN), a late osteogenesis and mineralization marker, had been evaluated by immunohistochemical evaluation. To this finish, sections had been deparaffined and rehydrated in Tris-buffered saline (TBS) (pH 7.4, 0.01 M Trizma base, 0.04 M Tris hydrochloride, 0.15 M NaCl), which was used for all additional incubations and rinse steps. Sections had been incubated in citrate buffer (pH 6) at 90 °C for antigen retrieval throughout 5 min. After a rinse step, sections had been blocked with 2% FBS in TBS–0.2% Triton X-100 (blocking buffer). The oblique immunohistochemical process was carried out by incubating the sections with collagen kind I (Col I) and osteocalcin (OCN) polyclonal antiserum (1/100) (Millipore, Barcelona, Spain) in blocking buffer in a single day at 4 °C. Sections had been rinsed thrice, then incubated with Cy3 donkey anti-rabbit F(ab) fragment (1/500) (Millipore, Barcelona, Spain) in blocking buffer for 1 h. After two rinse steps, the sections had been mounted with buffered glycerin. The evaluation of the samples was carried out in an optical microscope (Leica DM4000B) with a fluorescence lamp, and the pictures had been captured with a digital digicam (Leica DFC300FX). Response specificity was confirmed by changing the particular antiserum with regular serum, and an autofluorescence management was additionally carried out omitting each antisera.

Col I and OCN staining was measured utilizing computer-based picture evaluation software program (ImageJ, NIH, Bethesda, MD) by making use of a hard and fast threshold to pick out for constructive staining in several bone areas of the femur, each epiphyseal areas and within the diaphysis. Constructive pixel space was divided by the entire floor bone measurement. Values had been normalized to these measured from Apt-LPNPs-Cntrl group and reported as relative staining intensities.


To research the organs toxicity spleen, liver, lung, kidney, coronary heart, and mind had been extracted and ready for histological evaluation as beforehand described [36]. Briefly, the organs had been put up mounted by immersion for twenty-four h in the identical fixative and embedded in Paraplast®. Sections of 5 µm thick had been obtained, stained with hematoxylin-erythrosine and Cleveland-Rucker-Wolfe for topographical examine and analyzed by mild microscopy.

Statistical evaluation

Statistical evaluation was carried out utilizing SPSS 21.0 software program. First, the normality and homoscedasticity of the information had been checked utilizing the Kolmogorov–Smirnov take a look at and the Levene take a look at, respectively. This was adopted by a one-way evaluation of variance (ANOVA I) with a post-test of Tukey’s a number of comparability. The outcomes are expressed as imply ± commonplace error of the imply (SEM) and statistically vital variations are thought-about at p-values < 0.05.


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