• 圣淘沙名胜世界(新加坡)

    Sputum Sample Processing for Single Cell Isolation and Live Recovery for Single Cell RNA Sequencing

    Jason D Limberis, Alina Nalyvayko, Michele Tomasicchio, Shameem Jaumdally, anil pooran, Keertan Dheda, john.metcalfe

    Published: 2023-10-27 DOI: 10.17504/protocols.io.j8nlko9k5v5r/v1
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    Abstract

    Processing of clinical sputum samples for single live cell isolation for downstream applications.

    Before start

    Increasing the amount of sputum, by asking the patient to expectorate several time, will likely increase the final cell numbers.

    Steps

    Prepare Buffers

    1.

    5mM EDTA in PBS

    500ul 0.5M EDTA stock
    
    
    
    49.5ml PBS. Store at 4C
    

    10% BSA stock

    Add 1g BSA to 10ml PBS, mix gently till dissolved
    
    
    
    Filter sterilize & keep at 4C
    

    50mM MgCl2 solution

    Add 238mg of MgCl2 to 50ml of H2O 
    

    10% DMSO/FCS freezing mixture

    5mL DMSO

    `45mL` fetal calf serum (FCS)
    

    NALC in PBS 7.5Mass Percent NALC in PBS

    DNase

    Aliquoted into 100ul aliquots at 224kuml and stored at -20C
    
    Add 100ul to 40ml dissociation buffer to make a final conc of 0.56ku/ml.
    

    Collagenase IV

    Add `500µL` to `40mL` dissociation buffer to make a final conc of 0.05mg/ml
    
    
    
     Aliquoted `500µL` at 4mg/ml and stored at -20C.
    

    Make fresh for each use

    1% BSA in PBS

    5mL 10% BSA

    `45mL` PBS
    

    Dissociation buffer

    1.6mL of50millimolar (mM) MgC22

    `100µL` DNase
    
    
    
    `500µL` collagenase
    

    37.8mL PBS

    Sputum collection

    2.

    Collect an induced sputum, preferably 5mL or more in volume, and process as below as soon as possible.

    2.1.

    Weigh the sputum collection cup before and after the sputum collection.

    2.2.

    Estimate the volume of sputum collected using a graduated container of the same size.

    2.3.

    Record the viscosity (salivary, mucosalivary, purulent, mucopurulent)

    2.4.

    Record the time of sputum collection

    Bulk RNA sequencing

    3.

    Record the time of sputum processing

    4.

    Using a wide bore tip (or cut the bottom of a 1000µL) draw up ~200µL sputum. If the sample is too viscous for a pipette, use a syringe needle instead.

    5.

    Add to a 1.5ml tube containing 500µL Zymo RNA Shield

    6.

    Vortex tube for 0h 0m 10s

    7.

    Immediately transfer to -80°C

    Make a single cell suspension (scRNAseq)

    8.

    Add 40mL dissociation buffer into the collection tube containing the sputum sample

    9.

    Secure cap, manually invert the tube several times. Secure to a hula mixer (low setting) and incubate for 0h 10m 0s at Room temperature.

    Note: Big clumps should dissolve after 0h 10m 0s. Some small fibers may will remain.

    10.

    Add DTT to a final concentration of 1-2mM.

    Invert the tube several times and incubate for 0h 5m 0s

    11.

    Pass the dissociated sample through a 100 µm strainer on top of a new 50mL tube using an automated pipettor (do not pour). 350rcf,4°C

    12.

    Wash the strainer with 2mL of PBS

    13.

    Spin tube in a sealed bucket at 250rcf,4°C

    14.

    Remove 1000µL supernatant and place in a cryovial for Luminex Cytokine assays. Add 140µL of protease inhibitor and store at -80°C

    15.

    Aspirate the remainder of the supernatant and discard.

    16.

    Gently resuspend cell pellet in 1mL EDTA/PBS using a wide bore 1000µL tip

    17.

    Count cells using Turks protocol followed by paraformaldehyde fixation to decontaminate

    Long-term storage of cells (scRNAseq)

    18.

    Pre-cool CellCool and cryovials at 4°Cfor >2h 0m 0s

    19.

    Place cells On ice

    20.

    Gently mix the cells

    21.

    Centrifuge at 300rcf,4°C

    22.

    Discarded supernatant and resuspend cell pellets in pre-chilled (4°C) 10% DMSO/FCS solution (add dropwise)

    23.

    Dispense cell suspension in 500µL aliquots into the pre-cooled cryovials and place into CoolCell at -80°C

    Expected results

    24.

    Pilot samples

    ABCD
    SampleS1S2S3
    Viscositymucosalivarymucosalivarymucosalivary
    Volume used (ml)1046
    Total cells before freezing (10^6)2.20.92.9
    Total cells recovered after thawing (2 weeks after frozen; 10^6)0.880.481.33
    Percentage cell recovery post freezing (%)405346
    S2 400x
    S2 400x
    S3 100x
    S3 100x

    Clinical samples

    ABCDEFGHIJKLMN
    Sample IDTime to sputum processing (h.m)weight of sputum (g)volume of sputum (ml)viscosity of sputumTime to thaw (days)Total cell count pre freeze (x10^6)Total cell count taken forward pre freeze (x10^6)Total cell count post freeze (x10^6)Total cell count difference (x10^6)Live cell countDead cell countViability (%)Viability of prefreeze total (%)
    CC202.8517.815salivary6629.174.862.141.583.283323
    CC22<6.002.12mucoid6581.31.30.600.710.150.442612
    CC232.102.93mucosalivary6570.430.430.370.060.080.292118
    CC241.108.78mucosalivary6571.11.10.810.300.190.622317
    CC254.900.70.9mucosalivary6520.170.170.000.170.000.0000
    CC262.001.51.4mucosalivary6521.131.130.730.400.170.572315
    CC272.203.23mucosalivary6511.41.41.330.070.301.032322
    CC282.001210mucoid6443.222.74-0.740.292.451115
    CC332.0033mucosalivary6270.80.80.670.130.250.423731
    CC37<6.004.14mucosalivary6230.920.920.97-0.050.340.633537

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