Transfection Reagents

More Information

What Is Transfection?

Transfection is a method to introduce a foreign gene into cells to express the gene. This technique is used to analyze the function of the target gene and to produce proteins. It has contributed greatly to the advancement of life sciences.

Types of Transfection

Transfection of eukaryotic cells is mainly performed using physical, biological, and chemical methods. Each method has its own characteristics and is used for different purposes.

Physical Methods

Physical methods use stimuli to allow the nucleic acids to penetrate the cell membrane. Known methods include electroporation, microinjection, and laser methods. The most common method is electroporation. In electroporation, nucleic acids are allowed to pass through the cell membrane by electrical pulses. The physical stimulation of the cell membrane makes it possible to transfect nucleic acids into a wide range of cells with high efficiency. A downside is that it is very costly, because of the need for special equipment. It also has the disadvantage that some cells are susceptible to cytotoxicity caused by the physical stimulation.

Biological Methods

Biological methods use viruses. The methods take advantage of the ability of viruses to infect, resulting in very high transfection efficiency. Furthermore, they are highly compatible with in vivo transfection and have been used in many studies with laboratory animals. The disadvantages include complicated procedures for the preparation of viruses and the requirements to meet the biosafety level.

Chemical Methods

Chemical methods include lipofection and calcium phosphate co-precipitation methods. Among these, lipofection has become the most common transfection method. In lipofection, positively charged cationic lipids and negatively charged nucleic acids form complexes and enter the cells via endocytosis (Figure 1)^1,2).

The lipofection method is the easiest method of transfection due to its low cytotoxicity and simple procedures. On the other hand, its disadvantages include lower transfection efficiency compared to physical or biological methods, and the need for optimization of the protocol for each cell type and culture conditions. In recent years, manufacturers have developed transfection protocols for higher transfection efficiency and ease of use, and the performance is constantly improving.

Comparison of Transfection Methods

	Physical methods	Biological methods	Chemical methods
Representative methods	Electroporation Microinjection	Virus vectors	Lipofection Calcium phosphate co-precipitation
Advantages	High transfection efficiency Compatible with a wide range of cell types	High transfection efficiency Compatible with in vivo applications	Low cytotoxicity Simple procedures
Disadvantages	Requires specialized equipment High cost High cytotoxicity	Complicated procedures Biosafety requirements	Low transfection efficiency (depending on cell types) Variable transfection efficiency depending on cell types and culture conditions

References

1. Felgner, P. et al.: Proc. Natl. Acad. Sci. USA., 84(21), 7413(1987).
   Lipofection: a highly efficient, lipid-mediated DNA-transfection procedure
2. Felgner, J. H. et al.: J. Biol. Chem., 269(4), 2550(1994).
   Enhanced gene delivery and mechanism studies with a novel series of cationic lipid formulations