Computational Gene - Challenges

Challenges

Although mechanistically simple and quite robust on molecular level, several issues need to be addressed before an in vivo implementation of computational genes can be considered.

First, the DNA material must be internalised into the cell, specifically into the nucleus. In fact, the transfer of DNA or RNA through biological membranes is a key step in the drug delivery. Some results show that nuclear localisation signals can be irreversibly linked to one end of the oligonucleotides, forming an oligonucleotide-peptide conjugate that allows effective internalisation of DNA into the nucleus.

In addition, the DNA complexes should have low immunogenicity to guarantee their integrity in the cell and their resistance to cellular nucleases. Current strategies to eliminate nuclease sensitivity include modifications of the oligonucleotide backbone such as methylphosphonate and phosphorothioate (S-ODN) oligodeoxynucleotides, but along with their increased stability, modified oligonucleotides often have altered pharmacologic properties.

Finally, similar to any other drug, DNA complexes could cause nonspecific and toxic side effects. In vivo applications of antisense oligonucleotides showed that toxicity is largely due to impurities in the oligonucleotide preparation and lack of specificity of the particular sequence used.

Undoubtedly, progress on antisense biotechnology will also result in a direct benefit to the model of computational genes.