Supplies and reagents
Supplies and reagents have been included in Further file 1.
Extraction and purification of the PM
Entire blood samples have been collected from rats by cardiac puncture with EDTA-treated anticoagulant vacutainer tubes. After that, the entire blood was centrifuged at 200 × g for 20 min at 20 ℃. The supernatant fraction was collected and centrifuged at 800 × g for 15 min. The white sediments have been platelets, which have been resuspended with PBS containing EDTA and PGE1 to keep away from platelet activation. Then, platelets have been lysed by repeated freeze–thaw at − 80 °C and room temperature for 3 occasions, adopted by repeated washes with PBS. Subsequently, platelets have been additional damaged by the ultrasonic cell disruptor (SCIENTZ-950E) for five min on ice (100 W, 53KHZ) [11, 15]. Platelet membrane (PM) vesicles have been ready by steady extrusion by way of 0.2 and 0.1 μm polycarbonate filters (Avanti® Mini-Extruder set). Lastly, whole protein of PM was measured by BCA assay.
Synthesis of PTPN nanoparticles
pH-responsive tPA nanoparticles (TPN) have been synthesized as described in our earlier work [10]. Briefly, PEI–PBA was achieved by reacting 38.5 mg of PBA, 50 mg of PEI and acid-binding agent trimethylamine in 2 mL of DMSO at 70 °C for twenty-four h adopted by dialysis and lyophilization. PC–tPA was formatted through a Schiff base response between the aldehyde group on the PC and the first amino group on the tPA at 50:1 molar ratio. 29 μL of PC (1 mg/mL) was added into 100 μL of tPA resolution (1 mg/mL) at room temperature adopted by adjusting pH to eight.0. This response was stirred for 1 h after which eliminated extra PC by ultrafiltration. After that, obtained PC–tPA was saved at 4 ℃ for additional use.
Ready PEI–PBA and PC–tPA at mass ratio of three:1 have been combined to assemble a pH-responsive nanocomplex through boronate ester response. Briefly, PC–tPA resolution (0.15 mL, 0.12 mg/mL) was added dropwise to PEI–PBA resolution (0.15 mL, 0.36 mg/mL) below stirring for 10 min. In the meantime, mPEG-Dopamine (0.5 mg/mL) was added and continued stirring to acquire the TPN.
Then, TPN and ready PM have been combined at completely different protein mass ratios 1:10 for synthetizing PM coated TPN (PTPN) [16, 17]. In short, TPN (0.5 mL, 0.05 mg/mL) was combined with PM (0.5 mL, 0.5 mg/mL) and pre-warmed at 37 ℃ adopted by steady extrusion by way of 0.2 and 0.1 μm polycarbonate filters.
Characterization of nanoparticles
The particle measurement and zeta potential of nanoparticles suspended in numerous pH PBS options have been decided by dynamic mild scattering (DLS) zetasizer (Malvern, Zetasizer 3000). The soundness of TPN and PTPN (suspended in PBS or DMEM containing 10% FBS) was evaluated by DLS at 0 h, 12 h, 24 h, 2 d, and three d. As well as, transmission electron microscope (TEM) was utilized to visualise the morphology of TPN, PM and PTPN.
SDS–PAGE gel with silver staining and Western blot have been used to research protein profiles of the PM, TPN and PTPN. Briefly, equal quantities of protein (4 μg) of PM, TPN and PTPN have been separated on a ten% SDS–PAGE gel adopted by fixation with ethanol and acetic acid. Subsequently, the gels have been incubated with silver staining sensitizer for two min after which with silver nitrate for 10 min. Lastly, the gel was incubated with chromogen resolution and terminated with cease resolution. Equally, SDS–PAGE gel after electrophoresis was transferred to the 0.22 μm polyvinylidene difluoride membrane (PVDF) and incubated with anti-CD34, anti-CD61, and anti-CD42b in a single day. After that, the PVDF membrane was incubated with horseradish peroxidase (HRP)-conjugated secondary antibodies and detected by electro-chemiluminescence (GE, Amersham Imager600).
Cell mannequin
Main cardiomyocytes have been remoted and cultured in keeping with a beforehand established methodology [18]. Briefly, hearts harvested from the neonatal Sprague–Dawley (SD) rats have been serially digested with 0.1% trypsin. After that, single-cell suspension was added into cultural dish to take away the fibroblasts by differential attachment for 1 h. The purity of main cardiomyocytes was confirmed as > 80% by immunofluorescence staining of α-actinin (Further file 1: Fig. S1) [19]. Human Umbilical Vein Endothelial cells (HUVEC) have been bought from ATCC.
The oxidative stress cell mannequin induced by hypoxia and H2O2 was used on this work. Cell have been cultured in low glucose serum-free DMEM within the hypoxic chamber with 1% O2 for 12 h [20]. To imitate the oxidative stress induced by ischemia/reperfusion, cells have been handled with 500 μM H2O2 for two h [21].
Animal mannequin
Male ICR mice and SD rats aged 6–8 weeks have been bought from Shanghai JSJ Laboratory Animal Co., Ltd (Shanghai, China). All experimental procedures and animal research have been permitted by the Animal Ethics Committee of Shanghai Chest Hospital (Approval quantity: KS(Y)21,357).
Institution of the MI rat mannequin: Rats have been anesthetized by intraperitoneal (i.p.) injection of two% paraformaldehyde sodium, adopted by endotracheal intubation with 16G cannula (tidal quantity = 8 ml/kg, frequency = 80/min) [22]. Then, the chest was opened after blunt dissection of the pectoralis main muscle and pectoralis minor muscle. A 2.5 mm × 2.5 mm filter paper saturated with 15% FeCl3 resolution was positioned on the left anterior descending coronary artery (LAD) for five min to induce coronary thrombosis. Lastly, the filter paper was eliminated, and the incision was sutured layer by layer.
Institution of the femoral artery thrombosis rat mannequin: After anesthesia, the left femoral artery of the rat was uncovered and separated from the femoral vein and nerve. A 2.5 mm × 2.5 mm filter paper saturated with 15% FeCl3 resolution was positioned on the femoral artery [23].
Institution of the carotid artery thrombosis mannequin: ICR mice have been used to ascertain carotid artery thrombosis for stay imaging evaluation. Briefly, after anesthesia with 0.5% paraformaldehyde sodium and elimination of the cervical hair with depilatory cream, the carotid artery was uncovered below stereomicroscope (SZX7, Olympus) and coated with a 1 mm × 1 mm filter paper containing 15% FeCl3 resolution for five min [23].
Security analysis
Cell viability was measured by Cell Counting Equipment-8 (CCK-8) [24]. Intimately, HUVEC have been seeded into 96-well plates at a density of 5000 cells per effectively for 12 h. After that, the medium was changed with 100 μL of DMEM containing completely different concentrations (0, 100, 200, 500 and 1000 μg/ml) of tPA, TPN, PM and PTPN for six, 12, 24 and 48 h. Then, 10 μL of CCK-8 regent was added into every effectively and incubated for 1 h. Absorbance at 450 nm was measured utilizing the microplate reader (ThermoFihser, VarioscanLUX), and the cell viability was calculated utilizing the next equation:
$${textual content{Cell viability}}~(% )~ = frac{{{textual content{Absorbance}}~({textual content{experimental}}~{textual content{group}}) – {textual content{Absorbance}}~({textual content{clean}})}}{{{textual content{Absorbance}}({textual content{ctrl}}~{textual content{group}}) – {textual content{Absorbance}}~({textual content{clean}})}} occasions 100$$
Blood routine examination and clotting operate assay have been utilized to judge the biocompatibility of the nanocarrier elements. Briefly, 500 μL of regular saline, tPA, PM, TPN and PTPN (20 μg/mL) have been injected through the tail vein to the SD rats for acute toxicity check. After 24 h, blood was collected from the retro-orbital venous plexus and positioned in sodium citrate anticoagulant tubes. Blood routine examination was carried out with the automated blood analyzer (Mindray, BC-2800 Vet) and clotting operate was detected with the automated blood coagulation analyzer (Rayto, RAC-120).
Rats have been sacrificed at 4 weeks put up intravenous administration. Coronary heart, liver, spleen, lung and kidney have been fastened in 4% paraformaldehyde for twenty-four h, dehydrated, paraffin embedded, and Hematoxylin–Eosin (H&E) stained to look at tissue histomorphometry.
Binding effectivity of PTPN in vitro
To judge the PTPN binding effectivity to HUVEC in vitro [25, 26], HUVEC have been seeded right into a 24-well confocal plate at a density of two × 104 cells per effectively for 12 h. After that, FITC-labeled TPN, DiI-labeled PM or PTPN extracted with FITC-labeled TPN and DiI-labeled PM (500 ng/mL) was added into the medium. Then, cells have been moved to the hypoxic chamber with 1% O2 for 1 h. Subsequently, HUVEC have been counterstained with Hoechst. Lastly, binding effectivity was detected by confocal microscopy (ZEISS, LSM 980 with Airyscan2) and circulation cytometry (BD FACSCANTO II).
Thrombus-targeted capability in vivo
A carotid artery thrombosis mannequin was established to evaluate the thrombus-targeted capability of PTPN. 100 μL of FITC-labeled PTPN or FITC-labeled TPN (20 μg/ml) was injected through the tail vein of the ICR mice. The distribution of nanoparticles was monitored constantly for 3 h utilizing the In Vivo Imaging System (IVIS; PerkinElmer) [27].
Thrombolysis capability of PTPN in vitro
Rat complete blood was collected from the retro-orbital venous plexus and positioned in 1.5 mL microcentrifuge tubes for coagulation at room temperature [8]. After that, thrombus clots have been moved to 24-well plates and incubation with 200 μL of ddH2O, tPA (10 μg/mL), PM (10 μg/mL), TPN (10 μg/mL), PTPN (suspended in PBS, pH = 7.4, 10 μg/mL) or PTPN (suspended in PBS, pH = 7.4, 10 μg/mL) respectively. Thrombus clots have been extracted and photographed at 1 h or 3 h. After that, options containing lysed crimson blood cells have been moved to 96-well plate and absorbance have been detected at 538 nm.
Drug launch assay in vitro
Rhodamine labeled tPA was used to synthesize PTPN for launch assay. PTPN was dissolved in PBS at pH 7.4 and pH 6.4 respectively, then the discharge of Rhodamine-tPA at completely different time factors was obtained by ultrafiltration (100 kD, 3000 rpm, 10 min) and detected by fluorescence spectrophotometer.
Analysis of tPA exercise
As tPA mediates plasminogen conversion to plasmin, the exercise analysis of tPA launched from PTPN was measured. PTPN was suspended in PBS at pH 7.4 or pH 6.4 (10 μg/mL), respectively. Subsequently, 2 μL of plasmin substrate-AMC, 20 μL lytic PTPN resolution and 48 μL of plasmin assay buffer have been added into the plate to detect the plasmin exercise. Fluorescent sign was captured each 2 min for 20 min at 37 °C at Ex/Em = 360/450 nm by a fluorometry (ThermoFihser, VarioscanLUX).
Thrombolysis capability of PTPN in vivo
Nnormal saline, tPA, TPN or PTPN (0.1 mg/kg tPA) was administered through the tail vein in rats after institution of femoral artery thrombosis. After 6 h, the femoral artery was eliminated, and H&E staining was carried out to detect the recanalization of blood vessels. After FeCl3 induced AMI in rats, regular saline, TPN or PTPN (0.1 mg/kg tPA) was administered through the tail vein, and after 6 h the guts was harvested for staining.
Efficacy of PTPN in AMI therapy
CD31 immunohistochemical (IHC) staining and picrosirius crimson staining have been carried out to look at pathological adjustments of coronary heart. In short, rats in numerous teams have been sacrificed and perfused with PBS, after which with 4% paraformaldehyde. 5 μm paraffin sections have been used for histologic and IHC examine. For Picro Sirus Crimson staining, the sections have been immersed into picrosirius crimson resolution for 8 min, dehydrated with anhydrous ethanol twice, and dewaxed twice with dimethylbenzene (5 min every).
For CD31 immunofluorescence, the sections have been dewaxed and positioned in EDTA buffer (pH = 6.0) to restore antigens subsequently washed with PBS for thrice. After that, the sections have been immersed in 3% H2O2 resolution and shielded from mild for 25 min at room temperature. After washing with PBS, the sections have been blocked with 5% rabbit serum and incubated with anti-CD31 (1:200) at 4 °C in a single day. Then, the sections have been incubated with Cy3-conjugated secondary antibodies for 1 h at room temperature.
Mitochondrial morphology of main cardiomyocytes
Main cardiomyocytes have been seeded into the 24-well confocal plate at a density of two × 104/mL and cultured in a single day. The medium was changed with 500 μL of DMEM containing PBS, tPA, TPN or PTPN (500 ng/mL) for 1 h incubation. H2O2 was added into the cultural medium at a closing focus of 500 μM for two h at 37 °C. The medium was then changed with DMEM containing MitoTracker™ Crimson CMXRos and Hoechst 38,450 for 30 min at 37 °C. Lastly, main cardiomyocytes have been washed with PBS, and photographed with a confocal microscope.
Mitochondrial membrane potential assay
Main cardiomyocytes have been cultured and stimulated as described above. Then, the cells have been incubated with heat DMEM containing a JC-1 probe for 30 min at 37 °C, washed with heat PBS, re-stained with Hoechst 38,450, and photographed.
ATP manufacturing assay
Main cardiomyocytes have been seeded into an opaque white 96-well plate at a density of 5000 cells per effectively and cultured in a single day. The medium was changed with 100 μL of DMEM containing PBS or PTPN (500 ng/ml) for 1 h, incubated with H2O2 (500 nM) for two h, and equilibrated for 10 min at room temperature. 100 μL of detection reagent was added into every, shaken effectively, and incubated at room temperature for sign stabilization [28]. Luminescence was recorded by a plate reader (ThermoFihser, VarioscanLUX) at an integration time of 0.5 s.
Mitochondrial OxPhos protein expression
Oxidative phosphorylation (OxPhos) provides most power for eukaryotic cells, which consists of 5 protein subunits. Protein expression of OxPhos complexes have been detected by Western blot with OxPhos Rodent WB cocktail antibody. Different steps of Western blot have been the identical as described above.
RNA sequencing and evaluation
Main cardiomyocytes have been collected utilizing a scraper and counted. After washing with PBS, cells have been lysed with Trizol (1 mL/106 cells) and saved at − 80 °C. The library preparation and sequencing have been performed by the Haplox (China). Differential expression genes (DEGs) have been chosen by ∣Fold Change∣ ≤ 1.5 with P worth < 0.05. GO operate annotations and KEGG pathway database have been utilized to research the potential operate and pathway of DEGs. Statistical evaluation and graphical plotting have been carried out utilizing R software program.
Statistical evaluation
All numerical information are offered because the means ± SEM. Particulars and strategies are included within the determine legends. Variations between two teams have been in contrast with unpaired Scholar’s T check, and variations between a number of teams have been in contrast by one-way evaluation of variance (ANOVA) adopted by the Tukey’s a number of comparisons check. P values are famous in every determine and P worth < 0.05 was thought-about statistically important.
