Trial Outcomes & Findings for Fish Oil-derived N-3 Polyunsaturated Fatty Acids and Extracellular Vesicles (NCT NCT03203512)

Participants were recruited by using the Hugh Sinclair Unit of Human Nutrition volunteer database, emailing advertisements to staff and students of the University of Reading, to members of local community groups and to staff members in large local organisations and companies between Oct 2017 and March 2019. The first participant was enrolled on 16th Feb 2018 and the last participant was enrolled in March 2019.

Of the 416 participants contacted, a total of 58 participants were screened, of which 14 subjects failed to meet inclusion criteria and 2 declined to participate; 42 participants were enrolled on the trial and 40 completed the study with 2 dropped out before starting.

Fish Oil-derived N-3 Polyunsaturated Fatty Acids and Extracellular Vesicles

Circulating EVs were first isolated to obtain fractions 7\~9 by size exclusion chromatography (SEC) using Izon qEV columns (Izon Science Ltd, Oxford, United Kingdom). Fractions were then diluted with PBS to maintain the recommended concentration range of particles (1\~10\*10\^8 vesicles/ml) before being analysed on NanoSight 300 (Malvern, Amesbury, United Kingdom). For each analysis, five videos, each of 60 seconds duration, were captured with the camera level at 13. Data were analysed using the instrument software NTA 3.20, which can identify individual particles and estimate their sizes based on the Stokes-Einstein Equation. Finally, a threshold of 70nm was set for NTA to ensure minimal interference by small lipoproteins.

A 5μl of PFP was added into nonsticky microcentrifuge tubes (Alpha Laboratories Ltd, Hampshire, United Kingdom), which contained 5μl FcR blocking reagent (Miltenyi Biotec Ltd, Surrey, United Kingdom) and Annexin V buffer and incubated for 15 minutes in the dark at room temperature. Antibodies and isotype-matched controls were then added and samples incubated for another 15 minutes in the dark at room temperature. After incubation, samples were diluted with 200μl Annexin V buffer and transferred into FACS flow tubes (BD Biosciences, Wokingham, United Kingdom), ready to be analysed by FCM. PS+EVs were identified as Annexin V+EVs when triggering on APC fluorescence.

A 5μl of PFP was added into nonsticky microcentrifuge tubes (Alpha Laboratories Ltd, Hampshire, United Kingdom), which contained 5μl FcR blocking reagent (Miltenyi Biotec Ltd, Surrey, United Kingdom) and Annexin V buffer and incubated for 15 minutes in the dark at room temperature. Antibodies and isotype-matched controls were then added and samples incubated for another 15 minutes in the dark at room temperature. After incubation, samples were diluted with 200μl Annexin V buffer and transferred into FACS flow tubes (BD Biosciences, Wokingham, United Kingdom), ready to be analysed by FCM. Platelet-derived EVs (PDEVs) were identified as Annexin V+EVs which also stained positive for CD41-PE in APC vs PE quadrant plot, and endothelial-derived EVs (EDEVs) were identified as Annexin V+EVs which also stained positive for CD105- eFluor450 in APC vs PB quadrant plot.

A commercially available, plate-based thrombin generation assay was used to measure thrombin generation in either a standard, pooled vesicle and platelet-free plasma (termed vesicle-free plasma or VFP) or in the same VFP but with added circulating EVs from subjects in the intervention study. This enabled the assessment of TF-dependent thrombin generation specifically attributed to circulating EVs in samples from the intervention study. Results were presented as five variables: (i) lag-phase for initiation of thrombin generation after addition of the trigger (time to 1/6 of the peak height) (min); (ii) peak thrombin concentration (nM); (iii) time to reach the peak (min); (iv) velocity index, defined as = \[peak height/(time to peak - lag time)\] and (v) area under the curve, defined as endogenous thrombin potential (ETP) (expressed as nM thrombin × min)

A commercially available, plate-based thrombin generation assay was used to measure thrombin generation in either a standard, pooled vesicle and platelet-free plasma (termed vesicle-free plasma or VFP) or in the same VFP but with added circulating EVs from subjects in the intervention study. This enabled the assessment of TF-dependent thrombin generation specifically attributed to circulating EVs in samples from the intervention study. Results were presented as five variables: (i) lag-phase for initiation of thrombin generation after addition of the trigger (time to 1/6 of the peak height) (min); (ii) peak thrombin concentration (nM); (iii) time to reach the peak (min); (iv) velocity index, defined as = \[peak height/(time to peak - lag time)\] and (v) area under the curve, defined as endogenous thrombin potential (ETP) (expressed as nM thrombin × min)

A commercially available, plate-based thrombin generation assay was used to measure thrombin generation in either a standard, pooled vesicle and platelet-free plasma (termed vesicle-free plasma or VFP) or in the same VFP but with added circulating EVs from subjects in the intervention study. This enabled the assessment of TF-dependent thrombin generation specifically attributed to circulating EVs in samples from the intervention study. Results were presented as five variables: (i) lag-phase for initiation of thrombin generation after addition of the trigger (time to 1/6 of the peak height) (min); (ii) peak thrombin concentration (nM); (iii) time to reach the peak (min); (iv) velocity index, defined as = \[peak height/(time to peak - lag time)\] and (v) area under the curve, defined as endogenous thrombin potential (ETP) (expressed as nM thrombin × min)

A commercially available, plate-based thrombin generation assay was used to measure thrombin generation in either a standard, pooled vesicle and platelet-free plasma (termed vesicle-free plasma or VFP) or in the same VFP but with added circulating EVs from subjects in the intervention study. This enabled the assessment of TF-dependent thrombin generation specifically attributed to circulating EVs in samples from the intervention study. Results were presented as five variables: (i) lag-phase for initiation of thrombin generation after addition of the trigger (time to 1/6 of the peak height) (min); (ii) peak thrombin concentration (nM); (iii) time to reach the peak (min); (iv) velocity index, defined as = \[peak height/(time to peak - lag time)\] and (v) area under the curve, defined as endogenous thrombin potential (ETP) (expressed as nM thrombin × min)

A commercially available, plate-based thrombin generation assay was used to measure thrombin generation in either a standard, pooled vesicle and platelet-free plasma (termed vesicle-free plasma or VFP) or in the same VFP but with added circulating EVs from subjects in the intervention study. This enabled the assessment of TF-dependent thrombin generation specifically attributed to circulating EVs in samples from the intervention study. Results were presented as five variables: (i) lag-phase for initiation of thrombin generation after addition of the trigger (time to 1/6 of the peak height) (min); (ii) peak thrombin concentration (nM); (iii) time to reach the peak (min); (iv) velocity index, defined as = \[peak height/(time to peak - lag time)\] and (v) area under the curve, defined as endogenous thrombin potential (ETP) (expressed as nM thrombin × min)

96-well high-throughput aggregometry technique, allowing testing of a wide range of concentrations of different agonists, was used to examine the influence of n-3 PUFA supplementation on platelet function. Platelet-rich plasma (PRP) and platelet-poor plasma (PPP) from each study visit was used in the platelet aggregation assay using pre-prepared 96-well microplates, containing the agonists (ADP, EPI, TRAP-6 and U46619). Dose-response curves in response to each agonist were obtained and results were represented as a LogEC50 (log concentration of agonist, M, giving a response halfway between maximum and minimum aggregation).

96-well high-throughput aggregometry technique, allowing testing of a wide range of concentrations of different agonists, was used to examine the influence of n-3 PUFA supplementation on platelet function. Platelet-rich plasma (PRP) and platelet-poor plasma (PPP) from each study visit was used in the platelet aggregation assay using pre-prepared 96-well microplates, containing the agonists (CRP-XL). Dose-response curves in response to each agonist were obtained and results were represented as a LogEC50 (log concentration of agonist, mg/ml, giving a response halfway between maximum and minimum aggregation).

Ex vivo thrombus formation was measured by the addition of in vitro-generated PDEVs from stimulated platelets into whole blood under flow. Results were presented as three variables: (i) endpoint for ex vivo thrombus formation (FU); (ii) endpoint for ex vivo thrombus formation (FU); (iii) area under curve.

Ex vivo thrombus formation was measured by the addition of in vitro-generated PDEVs from stimulated platelets into whole blood under flow. Results were presented as three variables: (i) endpoint for ex vivo thrombus formation (FU); (ii) endpoint for ex vivo thrombus formation (FU); (iii) area under curve.

A 500μl aliquot of frozen PFP was defrosted at room temperature using a roller mixer and subjected to SEC for the isolation and purification of EVs. The fractions 7\~9 were pooled together, and 800μl of pooled fractions was prepared for total lipid extraction and methyl esterification. The EV total lipid methyl esters were then analysed by gas chromatography on a Hewlett-Packard 6890 series GC (Hewlett-Packard, California, United States), with the following protocol: split ratio was set as 30:1 for plasma and EV analysis. The injection volume was 1μl for plasma and 5μl for EVs, respectively. The temperature of both injector and detector were kept at 300°C and the temperature program was initial temperature 115°C for 2 minutes, increased at 10 °C/min to 200°C and hold at this temperature for 16 minutes, and finally increased at 60°C/min to 240°C for 2 minutes (total run time: 29.2 minutes). Samples were analysed by using ChemStation software and Microsoft Excel.

A 400μl aliquot of frozen PFP was defrosted and centrifuged to remove denatured protein. The 400μl of 0.9% NaCl was added to the PFP sample to make up 800μl in total, and 30μg of phosphatidylcholine (PC) and 15μg of phosphatidylethanolamine (PE) internal standards were then added for the quantitative analysis. After lipid extraction, separation of PC and PE, and methyl esterification of plasma phospholipid extracts, samples were analysed by GC.

A 250μl aliquot of frozen PFP was defrosted at room temperature using a roller mixer and centrifuged at 500xg for 5 minutes at room temperature (Eppendorf Centrifuge 5415 R, DJBlabcare, United Kingdom). Then the sample was analysed by a RANDOX clinical analyser (RANDOX Daytona+ Analyser, Randox Laboratories Ltd, United Kingdom) for the concentration of TC, TAG, HDL-C, LDL-C and TC/HDL-C ratio.

A 250μl aliquot of frozen PFP was defrosted at room temperature using a roller mixer and centrifuged at 500xg for 5 minutes at room temperature (Eppendorf Centrifuge 5415 R, DJBlabcare, United Kingdom). Then the sample was analysed by a RANDOX clinical analyser (RANDOX Daytona+ Analyser, Randox Laboratories Ltd, United Kingdom) for TC/HDL-C ratio.

Subjects were asked to have a rest for 10 mins before blood pressure detection, and then blood pressure cuff was placed firmly on their upper left arms approximately 2 cm above the elbow with the indicator mark on the cuff over the brachial artery to start measurement. Subjects should put their arms at the level of the heart and should not speak and cross their legs during the measurement. Measurement was performed three times and waited for 2 mins between each reading ((Omron M2 Upper Arm Blood Pressure Monitor, OMRON Healthcare Europe BV, United Kingdom). The average of the three readings was taken to obtain the final result.