This protocol allows for the reliable generation and characterization of blood outgrowth endothelial cells (BOECs) from a small volume of adult peripheral blood. BOECs can be used as a surrogate for endothelial cells from patients with vascular disorders and as a substrate for the generation of induced pluripotent stem cells.
Historically, the limited availability of primary endothelial cells from patients with vascular disorders has hindered the study of the molecular mechanisms underlying endothelial dysfunction in these individuals. However, the recent identification of blood outgrowth endothelial cells (BOECs), generated from circulating endothelial progenitors in adult peripheral blood, may circumvent this limitation by offering an endothelial-like, primary cell surrogate for patient-derived endothelial cells. Beyond their value to understanding endothelial biology and disease modeling, BOECs have potential uses in endothelial cell transplantation therapies. They are also a suitable cellular substrate for the generation of induced pluripotent stem cells (iPSCs) via nuclear reprogramming, offering a number of advantages over other cell types. We describe a method for the reliable generation, culture and characterization of BOECs from adult peripheral blood for use in these and other applications. This approach (i) allows for the generation of patient-specific endothelial cells from a relatively small volume of adult peripheral blood and (ii) produces cells that are highly similar to primary endothelial cells in morphology, cell signaling and gene expression.
Indtil for nylig var den postnatale generation af nye blodkar menes at forekomme udelukkende gennem en proces kendt som angiogenese, defineret som spiring af nye skibe fra endotelceller af allerede eksisterende fartøjer. 1. Denne proces kontraster fra vaskulogenese, eller de novo dannelsen af blodkar fra endotelceller progenitorer, som blev anset for at forekomme udelukkende under embryogenese. 2 har imidlertid nyere undersøgelser identificeres og isoleres cirkulerende endoteliale progenitorceller (EPC'er) i det perifere blod hos voksne. Disse celler besidder evnen til at differentiere til modne endotelceller i kultur og menes at deltage i postnatal vaskulogenese. 3,4
Protokoller til isolering og udvidelse af disse EPC'er involverer typisk kultur af perifere mononukleære celler (PBMNCs) i medier indeholdende endotelvækstfaktorer, herunder Vascular endotel vækstfaktor (VEGF) og fibroblastvækstfaktor-2. 5-8 EPC kulturer producere en række dramatisk forskellige celletyper. Indledende kulturer (<7 dage) domineres af en monocytiske celletype, der er kendt i litteraturen som "tidlige" EPC'er. På trods af deres navn, disse celler udtrykker monocyt markør CD14, er negative for progenitor markør CD34 og kun udtrykker minimale niveauer af den klassiske endotel markører CD31 og VEGF receptor 2 (VEGFR2). 5 Fortsat kultur giver anledning til en sekundær cellepopulation, kendt som sene udvækst EPC'er eller blod udvækst endotelceller (BOECs), som vises som diskrete kolonier af endotel-lignende celler. I modsætning til de monocytiske tidlige EPCs, BOECs, som også er blevet kaldt endotelceller kolonidannende celler (ECFCs), udvækst endotelceller eller sent-udvækst endotelceller, udviser brosten morfologi, der er typisk for endotheliale cellemonolag og er meget ens i overflademarkør5 og genekspression 9 til modne endotelceller.
Dannelsen af endotelceller-lignende celler fra perifert blod giver flere fordele, især til undersøgelse af endotelcelle dysfunktion associeret med vaskulære lidelser, såsom pulmonal arteriel hypertension (PAH) 10 eller von Willebrands sygdom. 11. Forud for tilgængeligheden af BOECs, endotel- celler kunne kun udledes af eksplanterede organer på dødstidspunktet eller organtransplantation, eller isoleret fra navlestrengen vene ved fødslen. Denne reducerede tilgængelighed udgjorde en alvorlig begrænsning for forståelsen af biologien af endotelceller fra patienter med hjerte-kar-lidelser, samt samspillet mellem endotelceller og enten blodceller eller vægmaleri celler. Endvidere isolering og dyrkning af en ren population af endotelceller fra disse kilder er teknisk udfordrende og cellerne afledt ved disse fremgangsmåder udviser kun en begrænd proliferativ kapacitet. BOECs Derfor tilbyder en værdifuld surrogat for isolering og dyrkning af patient-afledte primære endotelceller.
Ud over deres in vitro applikationer, BOECs er også potentielt anvendelige autologe celletransplantation behandlinger. Disse anvendelser indbefatter både endotelcelle transplantation for at fremme neovaskularisering (se 12 og referencer deri), samt genereringen af inducerede pluripotente stamceller (iPSCs). 13 BOEC-afledte iPSCs kan anvendes til sygdomsmodeller og tilbyde et stort potentiale som udgangspunkt materiale til autologe celleterapi. BOECs omprogrammere hurtigere og med en højere effektivitet end huden fibroblaster. Desuden BOECs også mulighed for generering af iPSCs der er fri for karyotypic abnormiteter, hvilket er et væsentligt element i enhver teknologi, der vil være egnet til translationelle applikationer. Evnen til at generere iPSCs fra en patientblodprøve enLSO eliminerer behovet for en hudbiopsi og generering af hudfibroblaster, hvilket letter genereringen af celler fra patienter med sårheling lidelser eller de meget unge.
Protokollen beskrevet nedenfor, der er godkendt af og gennemføres i overensstemmelse med retningslinjerne fra National Research Ethics service Komité (Øst), giver en enkel og pålidelig metode til generering af BOECs med mere end 90% effektivitet fra en relativt lille volumen (60 ml) i perifert blod. Disse celler er meget proliferativ og kan passeres gentagne gange, hvilket muliggør generering af hundreder af millioner af celler fra en enkelt prøve af blod.
We present a detailed protocol that allows for the robust and efficient derivation of BOECs from adult peripheral blood mononuclear cells (PBMNCs). Our protocol includes two important refinements that represent advances on previous methods of BOEC isolation.14-16 These include the absence of heparin in the initial PBMNC culture medium and the use of defined, embryonic stem cell-qualified serum. This latter refinement is of particular importance. Embryonic stem cell (ESC)-qualified serum is a more consistent grade of serum and, although it is not known yet what component(s) are enriched in the serum that benefit BOEC isolation, the impact of this defined serum on the efficiency of BOEC generation is clear in our hands. In addition, we have also had success in isolating BOECs using human serum, thereby allowing for the generation of BOECs for clinical translation. In our hands, this refined protocol results in the successful isolation of stable BOEC cultures from greater than 90% of donors, making it one of the most reliable BOEC generation methods reported thus far. Although the use of particular sera is critical to BOEC generation, it also represents a primary limitation of the current protocol. Future improvements to the technique could include the generation of these cells in serum-free, defined culture conditions.
Critical Steps in the protocol include processing blood samples as soon as possible after collection, complete harvesting of the buffy coat cells after density gradient centrifugation and the timely passaging of initial colonies from P0 to P1. This passaging step is critical to establishment of a stable isolation. Like other endothelial cells, BOECs appear to be very sensitive to plating density. If the plating density after passaging is too low, the BOECs will not proliferate. Conversely, if the colonies are allowed to become overconfluent before passaging, the cells will also cease to proliferate and have the tendency to convert into an elongated, mesenchymal cell phenotype. If few colonies appear from days 7 to 14, or if the colonies are small in size, troubleshooting can include increasing cell density by passaging P0 colonies into a T-25 flask instead of a T-75.
Once the technique is mastered, the resultant BOECs can be used in several applications, including in vitro studies of endothelial cell biology, disease modeling and drug screening, as well as in vivo cell transplantation therapies. An important consideration for the development of any cell therapy process is to use cells that are free from pathogenic mutations. We have previously shown that BOECs isolated using our protocol possess genomes that are free from copy number variations and are thus representative of the individual from which they were collected. In addition, we have also demonstrated that the majority of BOEC-derived iPSC lines are free from copy number variations.13 This contrasts with previous reports of copy number variation in fibroblast-derived iPSCs. To date, these cells remain the only iPSCs for which this degree of genomic fidelity has been reported. This feature is important for the field of iPSC biology and the use of iPSCs in disease modeling, drug screening and future cell transplantation therapies.
The authors have nothing to disclose.
This work was supported by grants funded by the British Heart Foundation (BHF), Dinosaur Trust, McAlpine Foundation, Fondation Leducq, Fight for Sight, the Cambridge Biomedical Research Centre, National Institute of Health Research including (i) the BHF Oxbridge Centre of Regenerative Medicine [RM/13/3/30159], (ii) the BHF Cambridge Centre of Research Excellence, (iii) Addenbrooke’s Hospital, Cambridge University Hospitals NHS Foundation Trust and (iv) Papworth Hospital NHS Foundation Trust, and supported the Cambridge NIHR BRC Cell Phenotyping Hub. MLO is funded by a BHF Intermediate Fellowship. FNK is funded by a BHF PhD Studentship.
For blood collection | |||
60 mL syringe with luer-lok tip | BD | 309653 | |
19G Surflo Winged Infusion Set | Terumo | SV-19BL | |
50 mL conical centrifuge tube | StarLab | E1450 | 2 per donor |
Sodium Citrate | Martindale Pharmaceuticals | 270541 | |
Name | Company | Catalog Number | Comments |
For buffy coat isolation | |||
Ficoll-Paque Plus | GE Healthcare | 17-1440-03 | |
Dulbecco’s PBS (without Ca2+ and Mg2+) | Sigma-Aldrich | D8537 | |
Sterile wrapped plastic transfer pipettes | Appleton Woods | KC231 | |
Turk’s Solution | Millipore | 1.093E+09 | |
Name | Company | Catalog Number | Comments |
For cell culture, passaging and freezing cells | |||
Type 1 Collagen (derived from rat tail) | BD Biosciences | 35-4236 | |
Dulbecco’s PBS (without Ca2+ and Mg2+) | Sigma-Aldrich | D8537 | |
0.02M Acetic Acid | Sigma-Aldrich | A6283 | prepared in reagent grade water |
Endothelial Growth Medium-2MV (containing Bullet Kit, but not serum) |
Lonza | CC-3202 | Note: It is essential that the medium does not contain heparin. Do not use EGM-2. |
Fetal Bovine Serum (U.S.), Defined | Hyclone | SH30070 | |
10x Trypsin EDTA | Gibco | T4174 | Dilute to 1x in PBS prior to use |
Heat Inactivated FBS | Gibco | 10500-064 | |
DMEM | Gibco | 41965-039 | |
DMSO | Sigma-Aldrich | 276855 | |
Nalgene Mr. Frosty Freezing Container | Sigma-Aldrich | C1562 | |
Name | Company | Catalog Number | Comments |
For flow cytometric characterization | |||
FITC-conjugated mouse anti-human CD14 | BD Biosciences | 555397 | Mouse IgG1k, Clone: WM59 Dilution: 1:20 |
FITC-conjugated mouse anti-human CD31 | BD Biosciences | 555445 | Mouse IgG1k, Clone: WM59 Dilution: 1:20 |
APC-conjugated mouse anti-human CD34 | BD Biosciences | 555824 | Mouse IgG1k, Clone: 581/CD34 Dilution: 1:20 |
FITC-conjugated mouse anti-human CD45 | BD Biosciences | 560976 | Mouse IgG1k, Clone: HI30 Dilution: 1:20 |
APC-conjugated mouse anti-human VEGFR2 | R&D Systems | FAB357A | Mouse IgG1, Clone: 89106 Dilution: 1:10 |
FITC-conjugated mouse IgG1k isotype control | BD Biosciences | 555748 | Clone: MOPC-21 Dilution: 1:20 |
APC-conjugated mouse IgG1k isotype control | BD Biosciences | 555751 | Clone: MOPC-21 Dilution: 1:20 |
APC-conjugated mouse IgG1k isotype control | R&D Systems | IC002A Dilution: 1:10 |
Clone: 11711 |
EDTA, 0.5M solution | Sigma-Aldrich | E7889 | |
Name | Company | Catalog Number | Comments |
For immunofluorescent microscopy | |||
Corning Costar 24-well tissue culture plate | Sigma-Aldrich | CLS3527 | |
Paraformaldehyde | Sigma-Aldrich | 158127 | |
BSA | Sigma-Aldrich | A7906 | |
Polysorbate 20 | Sigma-Aldrich | P2287 | |
Monoclonal mouse anti-human CD34 antibody | R&D Systems | MAB72271 | Clone 756510, IgG1, use at 10 μg/ml |
Polyclonal goat anti-human VE-cadherin (CD144) | R&D Systems | AF938 | Antigen affinity- purified IgG, use at 1:300 |
Monoclonal rabbit anti-human Von Willebrand Factor (vWF) | Abcam | ab154193 | Clone EPSISR15, use at 1:250 |
Donkey anti-mouse IgG (H+L) secondary antibody, Alexa Fluor 488 conjugate | Life Technologies | A-21202 | Polyclonal, 2 mg/ml, use at 1:200 |
Donkey anti-goat IgG (H+L) secondary antibody, Alexa Fluor 488 conjugate | Life Technologies | A-11055 | Polyclonal, 2 mg/ml, 1:200 |
Donkey anti-rabbit IgG (H+L) secondary antibody, Alexa Fluor 568 conjugate | Life Technologies | A-10042 | Polyclonal, 2 mg/ml, 1:200 |
DAPI (4′,6-Diamidino-2-phenylindole dihydrochloride) | Sigma-Aldrich | D9542 | use at 1 μg/ml |