Amity Science, Technology & Innovation Foundation (ASTIF) organized a Lecture by Dr. K.C. Gupta Director, Indian Institute of Toxicology Research, Lucknow on the topic: Chitosan- Polyethylenimine /DNA Nanocomposits as Efficient Carriers for Nucleic Acids at Amity University, Sector-125, Noida.
Dr. K C Gupta delivered a very informative Lecture wherein he shared a deep research related to Chitosan, its effects & usages. He also educated students and faculty about the Gene Therapy.
Basic Steps in Gene Delievery
- DNA condensation and Complexion
- Delievery of DNA complex to be target site
- Cellular penetration and internalization
- Endosome cleanage to release DNA into the cytoplasm
- Nuclear translocation
- Transcription followed by Translation into a protein
Gene therapy has become a promising strategy for the treatment of many inheritable or acquired diseases that are currently considered incurable. It requires safe and efficient vectors to transfer and deliver therapeutic genetic material to target tissues. Initially, the aim of gene therapy was to treat inherited genetic deficiencies, now-a-days, the focus of the current gene therapy clinical trials has shifted to the treatment of cancer. In the field of Cancer Therapy, Gene Therapy has shown promise as it offers a high potential of tumor selectivity compared to the traditional chemotherapeutic approaches. Currently, non-viral vectors, being safer than the viral counterparts, are under continuous development and optimization. Several cationic lipids, nanoparticles, dendrimers, cationic polymers have been exploited extensively due to their ability to condense DNA to form compact complexes, which facilitate intracellular entry and protect DNA from nucleases and degradation. Among all these, branched polyethylenimine (bPEI) is the most widely studied polymer because of its efficient capability to condense DNA and the resulting PEI/DNA complex can act as proton sponge.
The net positive charge exhibited by PEI polyplexes permit them to interact with cell membranes and internalize into the cell, both in vivo and in vitro systems, overcoming membrane barriers and allowing nuclear gene delivery and expression. High charge density on bPEI increases the transfection efficiency however it simultaneously contributes to increased cytotoxicity.
To improve the bioavailability of PEI for in vitro and in vivo applications, the modifications have been incorporated. Of these, pegylation offers certain advantages viz., (i) introduces biodegradable linkages in the cationic polymers, (ii) reduces toxicity, (iii) diminishes non-specific interactions with the serum proteins, and (iv)Improves the uptake of cationic polymer-DNA complexes. Alternatively, polysaccharide coatings have been used for these purposes. Some of them have found applications in active targeting also. Additionally, these polymers display well-documented biocompatibility and biodegradability. Our group has attempted to amalgamate the desirable properties of synthetic cationic polymer, PEI, and polysaccharides by developing a number of transfection reagents for efficient delivery of nucleic acids in vitro and in vivo. The ratio of two polymers, in a particular system, was optimized to obtain highest transfection efficiency with reduced cytotoxicity and particle size within the nanometer range. The resulting systems were demonstrated successfully as efficient carriers of nucleic acids (pDNA and siRNA) in a wide range of mammalian cells with almost negligible cytotoxicity compared to unmodified PEI. Chitosan also possess very poor buffering capacity in the range of endosomes and lysosomes and it also displays low transfection.Chitosan requires only 35 unit to release 30% pDNA avers Dr. Gupta.