Verwenden von Caco-2-Zellen, die Lipidtransport Studie der Darm
Summary
Caco-2 cells can serve as an in vitro model to study the enterocyte transport of lipids, and lipid-soluble drugs/vitamins. The permeable membrane system separates the apical from the basolateral compartment, while the lentivirus expression system offers an effective gene overexpression method. The isolation of lipoproteins is confirmed by TEM.
Abstract
Studies of dietary fat absorption are generally conducted by using an animal model equipped with a lymph cannula. Although this animal model is widely accepted as the in vivo model of dietary fat absorption, the surgical techniques involved are challenging and expensive. Genetic manipulation of the animal model is also costly and time consuming. The alternative in vitro model is arguably more affordable, timesaving, and less challenging. Importantly, the in vitro model allows investigators to examine the enterocytes as an isolated system, reducing the complexity inherent in the whole organism model. This paper describes how human colon carcinoma cells (Caco-2) can serve as an in vitro model to study the enterocyte transport of lipids, and lipid-soluble drugs and vitamins. It explains the proper maintenance of Caco-2 cells and the preparation of their lipid mixture; and it further discusses the valuable option of using the permeable membrane system. Since differentiated Caco-2 cells are polarized, the main advantage of using the permeable membrane system is that it separates the apical from the basolateral compartment. Consequently, the lipid mixture can be added to the apical compartment while the lipoproteins can be collected from the basolateral compartment. In addition, the effectiveness of the lentivirus expression system in upregulating gene expression in Caco-2 cells is discussed. Lastly, this paper describes how to confirm the successful isolation of intestinal lipoproteins by transmission electron microscopy (TEM).
Introduction
4 – Studien der intestinalen Aufnahme von Nahrungsfett und lipidlösliche Arzneimittel und Vitamine können in vivo unter Verwendung eines Lymphfistel Modell 1 durchgeführt werden. Jedoch sind die Operationstechniken involviert nicht nur anspruchsvoll, sondern auch kostspielig. Obwohl in vivo-Ansätzen auf fäkale Analysen können verwendet werden, basieren, sind sie hauptsächlich verwendet, um die prozentuale Aufnahme durch den Magen-Darm-2,5 bestimmen. Die in diesem Dokument beschriebenen in vitro-Modell ist kostengünstiger, und die Techniken beteiligt sind wohl weniger anspruchsvoll. Genetische Veränderung Studien sind auch wirtschaftlicher und weniger zeitaufwendig, wenn sie mit diesen in-vitro-Modell durchgeführt.
Da lipidlöslichen Materialien, die von Enterozyten genommen werden, in Lipoproteinen 6,7 verpackt ist, wird die Wirksamkeit dieser in vitro-Modell zu erzeugen Lipoproteine entscheidend. Die zwei Haupt intestinal Lipoproteine Chylomikronen und sehr geringer Dichte (VLDL). Chylomikronen, definiert als Lipoproteine mit 80 nm oder mehr im Durchmesser, werden ausschließlich durch den Dünndarm produziert, wenn Lipide in Fülle im Magen-Lumen vorhanden sind. Da sie die größte Lipoproteine Chylomikronen sind denkbar die effizientesten Lipidtransportern. Dieses in vitro-Modell, das in der Lage ist Chylomikronen 8 kann verwendet werden, um Nahrungsfettabsorption, lipidlösliches Vitamin Absorption durch den Darm und die orale Bioverfügbarkeit lipophiles Arzneimittel zu untersuchen. Die Anwesenheit von lipidlösliche Moleküle, Vitamine oder Drogen in der Lipoproteinfraktion ist ein Indikator für deren Absorption durch den Dünndarm. Wie zuvor erläutert, kann dieses Modell verwendet werden, um die orale Bioverfügbarkeit lipophilen Arzneimittel 6 zu verbessern.
Dieses Papier beschreibt, wie Caco-2-Zellen sollten in durchlässige Membran oder regelmäßige Gewebekulturschalen, wie die Lipid-mi beibehalten werdenBefestigung zur Stimulierung Lipoproteinsynthese sollten darauf vorbereitet sein, wie die Lentivirus-Expressionssystem verwendet werden, um effektiv eine Überexpression zu erreichen, und wie die isolierte Lipoproteine sollten analysiert werden.
Protocol
Representative Results
Discussion
In diesem Papier, um die beiden Systeme, die verwendet werden können, zu erhalten Caco-2-Zellen beschrieben werden, nämlich die normale Gewebekulturschale und die durchlässige Membran. Die Vorteile der Verwendung der permeablen Membransystem umfassen die Trennung der apikalen und basolateralen Kompartimenten, und die Fähigkeit, das Lipid-Mischung zu inkubieren, und gleichzeitig sammelt die Lipoproteinsekretion. Jedoch sind die durchlässigen Membraneinsätze teuer, und ihre Polycarbonat-Membran nicht für eine gute …
Disclosures
The authors have nothing to disclose.
Acknowledgements
This work was supported by the Seed Grant Award from California Northstate University College of Pharmacy (to AMN). The authors would like to thank California Northstate University College of Pharmacy for covering the publication cost of this article, and George Talbott for his help in editing this manuscript.
Materials
| DMEM | VWR | 16750-112 | Pre-warm the growth media in individual tissue culture dish before adding cells |
| FBS | Fisher | 3600511 | We do not heat inactivate our serum |
| Trypsin | VWR | 45000-660 | Cells can be washed with PBS prior to trypsin treatment |
| Permeable membrane system | Fisher | 7200173 | 10-cm dish, 3-mm pore size, polycarbonate membrane |
| 10 cm dish | Fisher | 08-772-E | Tissue culture dish |
| 15 cm dish | Fisher | 08-772-24 | Tissue culture dish |
| 24 well plate | Fisher | 12565163 | Tissue culture plate |
| Lipid-based transfection reagent | Fisher | PRE2691 | Can be substituted with other transfection reagent |
| Reduced serum media | Invitrogen | 11058021 | For transfection |
| pLL3.7 eGFP | Addgene | 11795 | https://www.addgene.org/11795/ |
| Bottle-top filter | Fisher | 9761120 | 0.45 mm pore |
| Polybrene | Fisher | NC9840454 | 10 mg/mL |
| Oleic acid | Sigma | 01383-5G | Prevent freeze-thaw cycle |
| Lecithin | Fisher | IC10214625 | Egg lecithin |
| Sodium taurocholate | Fisher | NC9620276 | Product discontinued; alternative catalog number: 50-121-7956 |
| Protease inhibitor cocktail tablet (EDTA-free) | Fisher | 5892791001 | Used mainly for samples that need TEM analysis |
| Polycarbonate ultracentrifuge tube | Fisher | NC9696153 | Reusing it multiple times will collapse the tube |
| Lid for ultracentrifuge tube | Fisher | NC9796914 | A tool is required to remove the tube/lid from rotor |
| Syringe | Fisher | 50-949-261 | Disposable |
| Syringe filter | Fisher | 09-719C | Pore size = 0.2 mm; nylon |
| Phosphotungstic acid | Fisher | AC208310250 | For preparing 2% phosphotungstic acid, pH 6.0 |
| Tweezer | Fisher | 50-238-62 | Extra fine and strong tips |
| Formvar/carbon grid | Fisher | 50-260-34 | Formvar/carbon film square grid 400 Copper |
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