Transfection reagents help to overcome the natural barriers to gene transfer by various strategies.
The steps involved in the transfer of a “gene” from the outside into the genome of the cell comprise of the following:
1. Compaction of the DNA,
2. Attachment to the cell surface,
3. Transport into the cytoplasm,
4. Import into the nucleus and
5. Insertion into the chromosomal DNA.
The mechanism by which a certain barrier is overcome is an important feature of the respective transfection reagent. In order to elucidate the difficulties in optimizing the genetic engineering of mammalian cells, the major steps of transfection as well as putative agents for reaching this goal will be discussed in detail in the following sections. The mechanisms for many of the above-mentioned five steps of transfection are still under discussion. This is especially the case for the later steps taking place inside the cell, i.e., transport into the cell and most importantly into the nucleus. The earlier stages of compaction and interaction with the cell surface are better understood. This has important consequences for our current ability to engineer transfection agents and procedures. It should be noted that man-made transfection procedures are still orders of magnitude less efficient than nature’s transfection agents, the viruses are. One to five infectious particles, i.e., viruses, per cell are sufficient in that case, compared to the 105– 106 plasmid molecules needed in most nonviral transfection methods.
Tags: Bio Technology, Bio Genetics, Gene Delivery