preparation of mouse pluripotent stem cells &#40;mpscs&#41; for transfection

Jämförande analys av framåt- och bakåttransfektionsmetoder på mPSCs

Delivery of DNA and RNA into mammalian cells serves as a core pillar of biomedical research1. A common method for introducing exogenous nucleic acids (NA) into mammalian cells is through transient transfection2,3. This technique relies on mixing NA with commercially available transfection reagents capable of delivering them into the recipient cells. Typically, NA is delivered via forward transfection, where cells adhering to a two-dimensional surface receive the transfection complex. While forward transfection for the most common established cell lines is robust and protocols are well-published, more niche cell types with non-monolayer morphologies do not transfect easily, limiting the amount of NA that can be delivered and the number of cells that receive it.
Pluripotent stem cells (PSCs) serve as an attractive model for understanding development and as a tool for regenerative medicine, given their ability to divide indefinitely and produce any bodily cell type. For mouse PSCs (mPSCs), routine in vitro culture conditions with 2 inhibitors and LIF&#160;(2i/LIF) maintain a dome-like colony morphology, directly limiting the number of cells exposed to a forward transfection4,5,6. To address this, a reverse transfection can be performed: cells are added to a dish containing media and transfection reagent, rather than adding transfection reagent to adherent cells7. While this increases the number of cells exposed to the reagent, it also requires the cells to be passaged and transfected concurrently.
Moving beyond simple single-NA transfections, researchers often aim to deliver several NA constructs into a population of cells in vitro. This is typically achieved through a co-transfection, where the NAs are mixed at a given ratio (1:1, 9:1, etc.) and are then combined with the chosen transfection reagent8. This yields a mix of NAs and reagent that preserves the original ratio of NAs to one another - while cells in the treatment may receive different amounts of this mix, they all receive the same ratio9. While this is advantageous when the desired ratio of parts is known, determining this ratio ahead of time can be labor-intensive, with each ratio constituting a different condition. One alternative is to perform a &#34;poly-transfection,&#34; where individual NAs are mixed with the transfection reagent independently from one another9. By combining transfection complexes containing individual NAs (rather than combining NAs before creating the complexes), researchers can explore a wide array of NA stoichiometries in a single transfection experiment9. This is particularly valuable in cases where the products of several NAs are expected to interact with one another, such as with inducible transcription systems or systems with feedback built in1,10,11. However, to do so effectively, a high transfection efficiency is needed. Indeed, as the number of unique transfected NAs increases, the probability of a given cell receiving all of the desired NAs decreases exponentially9, 12.
The following report describes a reverse transfection protocol for mPSCs using a cationic lipid-based transfection reagent, in which cells are exposed to the reagent-NA mix for a maximum of 5 min to maximize viability and minimize the time outside of typical culture conditions. Comparing this protocol to the standard forward transfection of these cells demonstrates a higher transfection efficiency and an increase in the total number of surviving transfected cells. By combining this reverse transfection with a three-plasmid poly-transfection involving simple fluorescent reporters, an expanded potential to screen NA ratios with high transfection efficiency is demonstrated.

Författare i fokus: Framsteg inom syntetiska genetiska enheter för manipulation av stamcellers öde och utveckling av cellulär terapi

En optimerad musembryonal stamcellsbaserad omvänd polytransfektionsteknik för snabb utforskning av nukleinsyraförhållanden

Our work generally focuses on using synthetic genetic devices to manipulate stem cell fate and behavior. By controlling cellular states, we aim to advance the development of next generation cellular therapies. Recently, a deeper understanding of the relationship between the dosage of a fate determining gene and the cell's lineage has been established.This was facilitated by the development of genetic controllers that are able to titrate a given gene precisely. Classic molecular biology techniques such as transfection or lentiviral transduction for simple gene over expression will always be a mainstay. However, our field has recently adopted synthetic devices that incorporate linear and non-linear feedback in order to obtain more complex outputs from delivered DNA.Gene dosage has a key role in determining the outcome of gene expression. When delivering multiple exogenous genes, a key experimental factor is how much of each gene will give the optimal or desired outcome. Our protocol allows researchers to rapidly scan across dosages in a single treatment, looking for the desired ratio of DNA devices.

Beredning av pluripotenta stamceller från möss (mPSC) för transfektion

För att förbereda en gelatinbelagd 24-brunnsplatta, tillsätt 200 mikroliter av 0,2% gelatinlösningen till varje brunn. Skaka försiktigt plattan för att jämnt fördela lösningen och låt brunnarna bestrykas i rumstemperatur. Efter 15 minuter tar du försiktigt bort eventuellt överblivet gelatin från brunnarna med hjälp av en vakuumsug.Tillsätt 0,5 ml nypreparerat NBIL-media i varje brunn. Och placera plattan i en vävnadsodlingsinkubator för att förvärma. Lägg 30 ml tvättmedel i ett 50 ml koniskt rör.Aspirera mediet från vävnadsodlingsskålen med mESC och tillsätt erforderlig mängd cellavskiljningsmedium. Efter tre till fem minuter pipetterar du upp och ner 15 till 20 gånger med en P1 000-pipett. Observera cellerna i mikroskop.För att säkerställa en encellssuspension, överför cellsuspensionen till ett 50 ml-rör som innehåller tvättmedia. Centrifugera suspensionen vid 300 G i fem minuter vid rumstemperatur och aspirera tvättmediet. Återsuspendera pelleten i cirka 300 mikroliter tvättmedel.

Research

JoVE Journal

Developmental Biology

Preparation of Mouse Pluripotent Stem Cells &#40;mPSCs&#41; for Transfection

An Optimized Mouse Embryonic Stem Cell Based Reverse Poly-Transfection Technique for Rapid Exploration of Nucleic Acid Ratios

Due to its relative simplicity and ease of use, transient transfection of mammalian cell lines with nucleic acids has become a mainstay in biomedical ...

Reverse and Forward Transfection of Mouse Pluripotent Stem Cells &#40;mPSCs&#41;

Bakåt- och framåttransfektion av pluripotenta stamceller från möss (mPSC)

Flow Cytometry Analysis of Transfected Mouse Pluripotent Stem Cells &#40;mPSCs&#41;

Flödescytometrianalys av transfekterade pluripotenta stamceller från möss (mPSCs)