What is Cell Transfection?

[ATGC2001]

Transfection is, at its most basic definition, the introduction of a foreign material (such as DNA, RNA molecules, or proteins) into a eukaryotic cell. In most cases, the term “transfection” is used to define mammalian cell references, though the literal and original meaning of the word transfection refer to "transformation”. However, transfection process could be transient (transfected sequence does't integrate into host cell DNA, and therefore doesn't get expressed from host DNA after few day after transfection event), or stable transfection (also known as "transformation", when transfected sequence integrate into host cell genomic DNA and expressed by host cell). Today, multiple methods of introducing foreign RNA or DNA into eukaryotic cells exist. One of the earliest and now considered unreliable methods was transfection by calcium phosphate. S. Bacchetti and F.L. Graham developed this process in 1977. They designed the HEPES-buffered saline solution (known as HeBS) that contained phosphate ions combined with a calcium chloride solution containing DNA to be transfected.

[transfection]

The delivery of genes to the eukaryotic cells is the main and key technique for studying the gene’s regulation and protein function. During the early 90’s, several cationic liposomal formulations were formulated and developed adopting the use of polybrene and calcium phosphate. This study had helped in the great improvement of the overall efficiency, but these self-combining formulations are familiar to be unstable, mostly toxic and can be affected by antibiotics or serum.

[biologist]

Transfection is the process through which materials (including plasmid DNA or siRNA) is transferred into pores in cell plasma membranes that allows uptake of genetic materials. For use with animal cells, transfection is also defined as a means for a change in cell properties caused by the introduction of nucleic acids (DNA, RNA, Protein). While various methods of transfection are utilized today, the process of stable transfection is defined as DNA sequence capable to retain beyond reproduction.

[biologist]

Basically, when DNA enters the nucleus of a cells it could integrate to DNA of eukaryotic cells, a process that can lead to stable expression of integrated construct (stable transfection process). A transfection is only considered stable if it is able to reproduce when cells divide and create daughter cells that retain the DNA that has been transfected into them. Stable transfection occurs as DNA undergoes mitosis and retains the characteristics of the transfected materials. The goal is to enable transfected genes to remain in the genome of a cell as well as its daughter cells in a group to produce a stable transfection. Basically, it is quite difficult to initiate and produce stable transfection because very small percentages of cells produced will soon die and be replaced with original genetic of that cell.

Transfection may be utilized through several different methods (chemical transfection, viral, electroporation) and using reagent such as polymers, nanoparticles, and liposomes, here is the link to detailed Transfection Resource - http://www.altogen.com/transfection.php

Biomedical research today utilize the potential to stably integrate genes into genomes of mammalian cells. Stable transfection also encourage the development of therapeutic antibodies and similar pharmaceutical products that could be useful in gene therapies.

[postdoc]

In vivo cell transfection of proteins, DNA, RNA, and small RNA (siRNA, shRNA, miRNA) can be achieved by novel PEGylated Liposome-based in vivo delivery system described at Biocompare article http://www.biocompare.com/Articles/NewTechnology/2708/PEG-Liposome-siRNA-In-Vivo-Transfection-Reagent.html. This invivo liposomal transfection reagent coated with biodegradable PEG and due to this remarkable feature - there is absence of innate immune response after reagent administration. Liposome component provides in vivo protection and directed delivery of cargo molecules into tissues. Company also provides custom encapsulation of target molecules (siRNA, protein, DNA) into PEG-liposome in vivo transfection particles.

[postdoc]

siRNA delivery efficiency (siRNA transfection) depends on many factors, including oligonucleotides’ chemistry, length, net charge, cell/tissue type and administration route. There are few studies aiming at selection of AS or aptamers with enhanced cell uptake, presumably through cell membrane nucleic acid channel. However they were only partially successful, and are limited to few cell types. Pre-optimized cell type specific transfection reagents are commercially available from Altogen Biosystems (http://www.altogen.com).

However, in vivo siRNA delivery is a real challenge and it appears that in certain cases it is most promising to study siRNA constructs directly in mice, omitting steps with primary cells and especially cancerous/dividing cells - that is time and money consuming and in many cases does not directly correlate from in vitro to in vivo results. There are several efficient highly efficient in vivo delivery technologies of siRNA in mice that yield desired (taggeted) localization:
(1) NANOPARTICLE-based In Vivo Transfection Reagent - http://altogen.com/mirna.php#nanoparticle
(2) PEG-Liposome based In Vivo Transfection Reagent - http://altogen.com/mirna.php
(3) LIPID-based In Vivo Transfection Reagent - http://www.altogen.com/mirna.php
(4) In Vivo Transfection Reagent (POLYMER-based) - http://www.altogen.com/mirna.php#polymer