Methods of Gene Delivery into Cells
A number of methods have been developed over the years for efficient transfer of genes in cell culture. Some common methods of plasmid DNA transfection are outlined below:
Here HEPES-buffered saline solution is mixed with a calcium chloride solution containing DNA for transfection to form a fine precipitate of calcium phosphate with DNA. The suspension of the precipitate is then added to the monolayer of cells. The cells take up the calcium-phosphate- DNA complexes by endocytosis and express genes.
In this case, gene is transferred with the help of tiny vesicles of bipolar phospholipids that fuse with the cell membrane, releasing the DNA into the cytoplasm.
It is the most efficient method of gene delivery into cells. Here, DNA is directly injected into the nucleus using a fine glass capillary under a microscope. However this method acquire a great effort as each and every cell has to be injected individually.
In this method, cells are mixed with the DNA and placed in a small chamber with electrodes connected to a specialized power supply. A brief electric pulse is applied, which is thought to 'punch holes' in the cell membrane, enabling the cell to take up DNA.