This protocol describes a method for efficiently transfecting siRNA in freshly isolated human villous cytotrophoblasts using microporation and identifying DNA-protein complexes in these cells. Transfected cells can be monitored by Western blot and EMSA analyses during the 4-day culture time.
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Method Article
siRNA Transfection and EMSA Analyses on Freshly Isolated Human Villous Cytotrophoblasts
In This Article
Summary
Abstract
Human primary villous cytotrophoblasts are a very useful source of primary cells to study placental functions and regulatory mechanisms, and to comprehend diseases related to pregnancy. In this protocol, human primary villous cytotrophoblasts freshly isolated from placentas through a standard DNase/trypsin protocol are microporated with small interfering RNA (siRNA). This approach provided greater efficiency for siRNA transfection when compared to a lipofection-based method. Transfected cells can subsequently be analyzed by standard Western blot within a time frame of 3-4 days post-transfection. In addition, using cultured primary villous cytotrophoblasts, Electrophoretic Mobility Shift Assay (EMSA) analysis was optimized and performed on extracts from days 1 to 4. The use of these cultured primary cells and the protocol described allow for an evaluation of the implication of specific genes and transcription factors in the process of villous cytotrophoblast differentiation into a syncytiotrophoblast-like cell layer. However, the limited time span allowable in culture precludes the use of methods requiring more time, such as generation of a stable cell population. Therefore testing of this cell population requires highly optimized gene transfer protocols.
Introduction
Human placental dysfunction is associated with the development of several pregnancy-associated diseases like preeclampsia and intrauterine growth restriction 1. An important cell constituent of the placenta is the trophoblasts, which can be classified as either extravillous or villous cytotrophoblasts. Upon fusion, villous cytotrophoblasts further differentiate into the syncytiotrophoblast layer, a multinuclear cell structure with an important role in feto-maternal exchange and hormone production 2. Human primary villous cytotrophoblasts and their differentiated counterparts represent important biological samples and allow researchers to study a ....
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Protocol
The UQAM ethics committee has approved these protocols, which are in accordance with the guidelines of the ethics committee of St-Luc Hospital of the Centre Hospitalier Universitaire de Montréal (Montréal, Canada). Participants signed an informed consent form.
1. Medium Preparation and Isolation of Primary Villous Cytotrophoblasts
- Prepare culture medium for human primary villous cytotrophoblasts by supplementing Dulbecco’s Modified Eagle’s Medium (DMEM) with 25 mM HEPES, 10% Fetal Bovine Serum (FBS) and 1% penicillin/streptomycin. Filter the prepared medium through sterile 0.22 µm filter and store in a -20 °C ....
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Results
Fresh placentas from term pregnancies were used to isolate human primary villous cytotrophoblasts to conduct the set of experiments presented in the Protocol section. Following their isolation, we first analyzed the purity of cytotrophoblasts through the use of the cytokeratin-7 marker (Figure 1). Cell preparations were thus stained using a monoclonal anti-cytokeratin-7 antibody. Figure 1 represents results from a typical experiment following purification.......
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Discussion
Studies on human placental function and development have been greatly improved by protocols aimed at optimizing isolation of various placental cell populations. One of the best studied placental cell population remains the villous cytotrophoblasts, the study of which has greatly benefited from optimized protocols permitting efficient and reliable isolation. This has further allowed a number of experiments, such as transfection and promoter studies. Using a previously described protocol 3, pure populations of p.......
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Disclosures
The authors have nothing to disclose.
Acknowledgements
This work was supported by a grant from the National Sciences and Engineering Research Council of Canada (NSERC) (#298527) (BB). CT was supported by an institutional FARE scholarship. AV was supported by a NSERC Graham Bell Ph.D. scholarship. BB held a Canada Research Chair in Human Retrovirology (Tier 2). Thanks to Beatrix Beisner for help in revising the text.
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Materials
| Name | Company | Catalog Number | Comments |
|---|---|---|---|
| HBSS without Ca2+, Mg2+ | Sigma | #H2387 | |
| HBSS (10x) | Sigma | #14060-057 | |
| DMEM High Glucose without Hepes | Gibco | #12100-061 | |
| Hepes (1 M) | Gibco | #15630-080 | |
| Penicillin-Streptomycin-Neomycin (100x) | Gibco | #15640-055 | |
| Amphotericin B | Sigma | #A2411 | |
| CaCl2 | Sigma | #C4901 | |
| MgSO4.7H2O | Sigma | #M | |
| Fetal bovine serum | Gibco | #16170-078 | |
| Percoll | Sigma | #P-1644 | For density gradient |
| Syncytin-2 siRNA | Ambion Life technologies | #AM16708 | |
| Scrambled siRNA | Qiagen | # SI03650318 | |
| DNase I | Sigma-Aldrich | #D5025 | |
| Trypsine, type I | Sigma | #T8003 | |
| DharmaFECT Lipotransfection reagents | GEhealthcare | # T-2001-01 | |
| Trypsin/EDTA | Life technologies | #25300-062 | |
| Protease Inhibitor Cocktail | Roche Diagnostic | #11873580001 | |
| Pierce BCA Protein Assay Kit | Thermo Scientific | #23225 | |
| BSA | Sigma | #A7906 | |
| TWEEN 20 | Sigma | #P9416 | |
| Anti-rabbit IgG, HRP-linked antibody | Cell Signaling | #7074 | |
| BM Chemiluminescence Western Blotting Substrate (POD) | Roche Diagnostic | #11500708001 | |
| DPBS | Life technologies | #14287-080 | |
| T4 Polynucleotide Kinase | NEB | #M0201S | |
| ATP, [γ-32P] | Perkin Elmer | #BLU002A100UC | |
| Acrylmide | Sigma | #A9099 | |
| TEMED | Life technologies | #17919 | |
| Ammonium Persulfate | Sigma | #A3678 | |
| Anti-human cytokeratin-7 antibody clone LP5K, FITC conjugated | Millipore | CBL194F | Dilution 1:200 |
| FcR blocking reagent | Miltenyi Biotec | 130- 059-901 | Dilution 1:10 |
| Flow Cytometer BD Acuri system | Becton Dickinson | ||
| Microporator MP-100 apparatus | Digital Bio | ||
| Resuspension Buffer R (Neon Transfection System 100 µl Kit) | Life technologies | MPK10096 | |
| PVDF membrane | Millipore | IPVH00010 | Activate with methanol |
| Anti-human GAPDH antibody | Santa Cruz Biotechnology | sc-137179 | 1:500 |
| HorseRadish Peroxidase (HRP)-conjugated goat anti-rabbit antibody or anti-mouse antibody | Cell Signalling | #7074 | 1:10,000 |
| HorseRadish Peroxidase (HRP)-conjugated goat anti-mouse antibody | Cell Signalling | #7076 | 1:10,000 |
| NE-PER Nuclear and Cytoplasmic Extraction Reagent | Thermo Scientific | #78833 | |
| G-25 column | GE Healthcare | #27-5325-01 | |
| Chemiluminsescence and fluorescence imaging device | Montréal Biotech | Fusion FX5 | |
| 4% native gel | Home made | ||
| PBS | Home made | 1x | |
| Personal Molecular Imager (PMI) System | BioRad |
References
- Huppertz, B. Placental origins of preeclampsia: challenging the current hypothesis. Hypertension. 51, 970-975 (2008).
- Huppertz, B. IFPA Award in Placentology Lecture: Biology of the placental syncytiotrophoblast--myths and facts. Placenta....
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