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21.3 Electroporation of plasmid DNA into muscles and skin

DNA can be efficiently introduced into muscle and skin in vivo by electroporation. Electroporation of DNA has been known to increase the transduction efficiency by 10 fold higher as compare to normal DNA injection. It is still not clear whether the efficiency of electroporation is more because of more expression level or with more cells transfected at the same time. Diseases like anemia and muscular dystrophy is successfully targeted by using naked DNA.

21.4 Intravenous injection of plasmid DNA

Intravenous administration of gene in the form of plasmid DNA is highly efficient way to transfer the DNA to the target site. The intravenous injection distributes the gene to each and every cell of the body within no time because of the involvement of circulatory system. Intravenous delivery may be systemic in case required for the whole body or local for specific tissue or organ system. Intravenous delivery of cationic-DNA complex results in efficient gene expression in the endothelial lining of the blood vessels and to hepatocytes. The expression of transgene to the hepatocytes following the intravenous injection is mostly directed by the portal system.

Some facts: The mammalian DNA contains CpG sequences that are methylated while the bacterial DNA is not methylated. Therefore the plasmid DNA originated from bacterial origin shows an immune response after entering into the mammalian system. Minimizing the CpG sequence in a plasmid construct decreases the immune response and increases the transgene expression. n general cells are originated from three lineages, ectoderm, mesoderm, and endoderm. The integrity of all the three types is lost when grown in cell culture flask in vitro .