The protocol presents a method for culturing and processing lingual organoids derived from taste stem cells isolated from the posterior taste papilla of adult mice.
The sense of taste is mediated by taste buds on the tongue, which are composed of rapidly renewing taste receptor cells (TRCs). This continual turnover is powered by local progenitor cells and renders taste function prone to disruption by a multitude of medical treatments, which in turn severely impacts the quality of life. Thus, studying this process in the context of drug treatment is vital to understanding if and how taste progenitor function and TRC production are affected. Given the ethical concerns and limited availability of human taste tissue, mouse models, which have a taste system similar to humans, are commonly used. Compared to in vivo methods, which are time-consuming, expensive, and not amenable to high throughput studies, murine lingual organoids can enable experiments to be run rapidly with many replicates and fewer mice. Here, previously published protocols have been adapted and a standardized method for generating taste organoids from taste progenitor cells isolated from the circumvallate papilla (CVP) of adult mice is presented. Taste progenitor cells in the CVP express LGR5 and can be isolated via EGFP fluorescence-activated cell sorting (FACS) from mice carrying an Lgr5EGFP-IRES-CreERT2 allele. Sorted cells are plated onto a matrix gel-based 3D culture system and cultured for 12 days. Organoids expand for the first 6 days of the culture period via proliferation and then enter a differentiation phase, during which they generate all three taste cell types along with non-taste epithelial cells. Organoids can be harvested upon maturation at day 12 or at any time during the growth process for RNA expression and immunohistochemical analysis. Standardizing culture methods for production of lingual organoids from adult stem cells will improve reproducibility and advance lingual organoids as a powerful drug screening tool in the fight to help patients experiencing taste dysfunction.
In rodents, lingual taste buds are housed in fungiform papillae distributed anteriorly, bilateral foliate papillae posteriorly, as well as a single circumvallate papilla (CVP) at the posterodorsal midline of the tongue1. Each taste bud is composed of 50-100 short-lived, rapidly renewing taste receptor cells (TRCs), which include type I glial-like support cells, type II cells that detect sweet, bitter, and umami, and type III cells that detect sour2,3,4. In the mouse CVP, LGR5+ stem cells along the basal lamina produce all TRC types as well as non-taste epithelial cells5. When renewing the taste lineage, LGR5 daughter cells are first specified as post-mitotic taste precursor cells (type IV cells) that enter a taste bud and are capable of differentiating into any of the three TRC types6. The rapid turnover of TRCs renders the taste system susceptible to disruption by medical treatments, including radiation and certain drug therapies7,8,9,10,11,12,13. Thus, studying the taste system in the context of taste stem cell regulation and TRC differentiation is vital for understanding how to mitigate or prevent taste dysfunction.
Mice are a traditional model for in vivo studies in taste science since they have a taste system organized similarly to humans14,15,16. However, mice are not ideal for high throughput studies, as they are expensive to maintain and time-consuming to work with. To overcome this, in vitro organoid culture methods have been developed in recent years. Taste organoids can be generated from native CVP tissue, a process in which organoids bud off from isolated mouse CVP epithelium cultured ex vivo17. These organoids display a multilayered epithelium consistent with the in vivo taste system. A more efficient way to generate organoids that does not require ex vivo CVP culture was developed by Ren et al. in 201418. Adapting methods and culture media first developed to grow intestinal organoids, they isolated single Lgr5-GFP+ progenitor cells from mouse CVP and plated them in matrix gel19. These single cells generated lingual organoids that proliferate during the first 6 days of culture, begin to differentiate around day 8, and by the end of the culture period contain non-taste epithelial cells and all three TRC types18,20. To date, multiple studies utilizing the lingual organoid model system have been published17,18,20,21,22; however, methods and culture conditions used to generate these organoids vary across publications (Supplementary Table 1). Thus, these methods have been adjusted and optimized here to present a detailed standardized protocol for the culture of lingual organoids derived from LGR5+ progenitors of adult mouse CVP.
Lingual organoids provide a unique model for studying the cell biological processes driving taste cell development and renewal. As the applications of lingual organoids expand and more labs move toward utilizing in vitro organoid models, it is important that the field strives to develop and adopt standardized protocols to improve reproducibility. Establishing lingual organoids as a standard tool within taste science would enable high throughput studies that tease apart how single stem cells generate the differentiated cells of the adult taste system. Additionally, lingual organoids could be employed to rapidly screen drugs for potential impacts on taste homeostasis, which could then be investigated more thoroughly in animal models. This approach ultimately will enhance efforts to devise therapies that improve the quality of life for future drug recipients.
Reported here is an efficient and readily repeatable method for culturing, maintaining, and processing lingual organoids derived from adult mouse taste stem cells. It was found that using three CVPs from 8 to 20-week-old Lgr5–EGFP mice is sufficient to obtain ~10,000 GFP+ cells for experimental use, resulting in 50 wells plated at a density of 200 cells per well in 48-well plates. Removal of CVP trench epithelia is optimized by injecting the lingual epithelium with freshly made Dispase II and type-I C…
The authors have nothing to disclose.
The authors would like to thank Dr. Peter Dempsey and Monica Brown (University of Colorado Anschutz Medical Campus Organoid and Tissue Modeling Shared Resource) for providing WNR conditioned media and valuable discussions. We also thank the University of Colorado Cancer Center Cell Technologies and Flow Cytometry Shared Resources, especially Dmitry Baturin, for cell sorting expertise. This work was funded by: NIH/NIDCD R01 DC012383, DC012383-S1, DC012383-S2, and NIH/NCI R21 CA236480 to LAB, and R21DC016131 and R21DC016131-02S1 to DG, and F32 DC015958 to EJG.
Antibodies | |||
Alexa Fluor 546 Donkey anti Goat IgG | Molecular Probes | A11056, RRID: AB_142628 | 1:2000 |
Alexa Fluor 546 Goat anti Rabbit IgG | Molecular Probes | A11010, RRID:AB_2534077 | 1:2000 |
Alexa Fluor 568 Goat anti Guinea pig IgG | Invitrogen | A11075, RRID:AB_2534119 | 1:2000 |
Alexa Fluor 647 Donkey anti Rabbit IgG | Molecular Probes | A31573, RRID:AB_2536183 | 1:2000 |
Alexa Fluor 647 Goat anti Rat IgG | Molecular Probes | A21247, RRID:AB_141778 | 1:2000 |
DAPI (for FACS) | Thermo Fischer | 62247 | |
DAPI (for immunohistochemistry) | Invitrogen | D3571, RRID:AB_2307445 | 1:10000 |
Goat anti-CAR4 | R&D Systems | AF2414, RRID:AB_2070332 | 1:50 |
Guinea pig anti-KRT13 | Acris Antibodies | BP5076, RRID:AB_979608 | 1:250 |
Rabbit anti-GUSTDUCIN | Santa Cruz Biotechnology Inc. | sc-395, RRID:AB_673678 | 1:250 |
Rabbit anti-NTPDASE2 | CHUQ | mN2-36LI6, RRID:AB_2800455 | 1:300 |
Rat anti-KRT8 | DSHB | TROMA-IS, RRID: AB_531826 | 1:100 |
Equipment | |||
2D rocker | Benchmark Scientific Inc. | BR2000 | |
3D Rotator | Lab-Line Instruments | 4630 | |
Big-Digit Timer/Stopwatch | Fisher Scientific | S407992 | |
Centrifuge | Eppendorf | 5415D | |
CO2 tank | Airgas | CD USP50 | |
FormaTM Series 3 Water Jackeed CO2 Incubator | Thermo Scientific | 4110 | 184 L, Polished Stainless Steel |
Incucyte | Sartorius | Model: S3 | Cancer Center Cell Technologies Shared Resource, University of Colorado Anschutz Medical Campus |
MoFlo XDP100 | Cytomation Inc | Model: S13211997 | Gates Center Flow Cytometry Core, University of Colorado Anschutz Medical Campus |
Orbital Shaker | New Brunswick Scientific | Excella E1 | |
Real-Time PCR System | Applied Biosystems | 4376600 | |
Refrigerated Centrifuge | Eppendorf | 5417R | |
Spectrophotometer | Thermo Scientific | ND-1000 | |
Stereomicroscope | Zeiss | Stemi SV6 | |
Thermal Cycler | Bio-Rad | 580BR | |
Vortex | Fisher Scientific | 12-812 | |
Water bath | Precision | 51220073 | |
Media | |||
A83 01 | Sigma | SML0788-5MG | Stock concentration 10 mM, final concentration 500 nM |
Advanced DMEM/F12 | Gibco | 12634-010 | |
B27 Supplement | Gibco | 17504044 | Stock concentration 50X, final concentration 1X |
Gentamicin | Gibco | 15750-060 | Stock concentration 1000X, final concentration 1X |
Glutamax | Gibco | 35050061 | Stock concentration 100X, final concentration 1X |
HEPES | Gibco | 15630080 | Stock concentration 100X, final concentration 1X |
Murine EGF | Peprotech | 315-09-1MG | Stock concentration 500 µg/mL, final concentration 50 ng/mL |
Murine Noggin | Peprotech | 250-38 | Stock concentration 50 µg/mL, final concentration 25 ng/mL |
N-acetyl-L-cysteine | Sigma | A9165 | Stock concentration 0.5 M, final concentration 1 mM |
Nicotinamide | Sigma | N0636-100g | Stock concentration 1 M, final concentration 1 mM |
Pen/Strep | Gibco | 15140-122 | Stock concentration 100X, final concentration 1X |
Primocin | InvivoGen | ant-pm-1 | Stock concentration 500X, final concentration 1X |
SB202190 | R&D Systems | 1264 | Stock concentration 10 mM, final concentration 0.4 µM |
WRN Conditioned media | Received from Dempsey Lab (AMC Organoid and Tissue Modeling Share Resource). Derived from L-WRN (ATCC® CRL-3276™) cells | ||
Y27632 dihydochloride 10ug | APExBIO | A3008-10 | Stock concentration 10 mM, final concentration 10 µM |
Altro | |||
1 ml TB Syringe | BD Syringe | 309659 | |
2-Mercaptoethanol, min. 98% | Sigma | M3148-25ML | β-mercaptoethanol |
2.0 mL Microcentrifuge Tubes | USA Scientific | 1420-2700 | |
48-well plates | Thermo Scientific | 150687 | |
5 3/4 inch Pasteur Pipets | Fisherbrand | 12-678-8A | |
Albumin from bovine serum (BSA) | Sigma Life Science | A9647-100G | |
Buffer RLT Lysis buffer | QIAGEN | 1015750 | |
Cell Recovery Solution | Corning | 354253 | |
Cohan-Vannas Spring Scissors | Fine Science Tools | 15000-02 | |
Collagenase from Clostridium histolyticum, type I | Sigma Life Science | C0130-1G | |
Cultrex RGF BME, Type 2, Pathclear | R&D Systems | 3533-005-02 | Matrigel |
Dispase II (neutral protease, grade II) | Sigma-Aldrich (Roche) | 4942078001 | |
Disposable Filters | Sysmex | 04-0042-2316 | |
Dulbecco’s Phosphate Buffered Saline pH 7.4 (1X) (Ca2+ & Mg2+ free) | Gibco | 10010-023 | |
Dulbecco’s Phosphate Buffered Saline with Ca2+ & Mg2+ | Sigma Life Sciences | D8662-500ML | |
Dumont #5 Forceps | Fine Science Tools | 11252-30 | |
EDTA, 0.5M (pH 8.0) | Promega | V4231 | |
Elastase Lyophilized | Worthington Biochemical | LS002292 | |
Extra Fine Bonn Scissors | Fine Science Tools | 14084-08 | |
Fetal Bovine Serum (FBS) | Gibco | 26140-079 | |
Fluoromount G | SouthernBiotech | 0100-01 | |
HEPES Solution | Sigma Life Science | H3537-100ML | |
HyClone Tryspin 0.25% + EDTA | Thermo Scientific | 25200-056 | |
iScript cDNA Synthesis Kit | Bio-Rad | 1706691 | |
Modeling Clay, Gray | Sargent Art | 22-4084 | |
Needle | BD Syringe | 305106 | |
Normal Donkey Serum | Jackson ImmunoResearch | 017-000-121 | |
Normal Goat Serum | Jackson ImmunoResearch | 005-000-121 | |
Paraformaldehyde | Sigma-Aldrich | 158127 | |
PowerSYBR Green PCR Master Mix | Applied Biosystems | 4367659 | |
RNeasy Micro Kit | QIAGEN | 74004 | |
Safe-Lock Tubes 1.5 mL | Eppendorf | 022363204 | |
Sodium Chloride | Fisher Chemical | 7647-14-5 | |
Sodium Phosphate dibasic anhydrous | Fisher Chemical | 7558-79-4 | |
Sodium Phosphate monobasic anhydrous | Fisher Bioreagents | 7558-80-7 | |
SuperFrost Plus Microscope Slides | Fisher Scientific | 12-550-15 | |
Surgical Scissors – Sharp | Fine Science Tools | 14002-14 | |
Triton X-100 | Sigma Life Science | T8787-100ML | |
VWR micro cover glass | VWR | 48366067 | 22x22mm |