MO22 Biologics 4 (Nucleic Acids As Therapudics) Flashcards
What is the relationship between the central dogma of molecular biology and nucleic acid based therapies
Nuclei acid based therapies manipulate the flow of genetic information to treat diseases. This could be by replacing as gene or modifying the amount of mRNA in the cell.
What is gene therapy compared to nucleic acid therapy?
Gene therapy focuses on introducing functional genes or modifying genes to treat diseases by replacing, repairing or regulating faulty or missing genes. A gene is delivered into the cell where it can be transcribed into a functional protein. It is used for monogenic disorders and leads to permanent or longer term gene expression but has challenges like its high cost and safety concerns.
Nucleic acid therapy is broader, including RNA, DNA or analog based strategies, gene silencing, and genome editing beyond simply gene replacement.
Compare Ex Vivo to In Vivo routes of administration
Ex vivo- genetically modified patient derived cells which are reintroduced back to patients. Target cells are extracted from the patient where they are then grown, gene edited and then the corrective genes are delivered back into the patients body. Performed outside the body. Systemic safety in circulation during delivery is not a concern. Cell expansion (reproduction of cells with modified genetic functions) =long lasting therapeutic response.
In vivo- delivered straight into the patients body via local injection or systemic injection, can be a risk as the DNA can go into other non-target cells.
Describe the process of gene therapy
- Genetically disabled retrovirus (modified to deliver gene but not replicate) has cloned gene from bacterium incorporated into the virus.
- Cells from patient are removed and cultured in a lab.
- Cells are infected with retrovirus containing the required gene.
- Gene containing cells are reinfused into patient, genetically altered cells now produce gene.
What are the 2 types of gene therapy?
-somatic: transfer of a section of DNA to any cell of the body that does not produce sperm or eggs. The effect of gene therapy is not passed on to kids.
-germline: transfer of genes to sperm or eggs which then will be passed on to kids. Currently prohibited as large potential for -ve side effects.
What is mRNA therapy including some examples and limitations
-delivering the nucleic acid gene into the cell cytosol bypassing the need to go into the nucleus and transiently produces the desired protein. Does not alter the genome. Considered to be more safe and controllable.
- limitations include that it must be kept at extremely cold chain conditions making it less accessible and requires repeated dosing since mRNA degrades over time.
- used for vaccines, potential for use as an individualised cancer treatment.
What is Antisense oligonucleotide therapy?
ASO: reducing or modifying the production of disease related proteins. Single stranded antisense oligonucleotides bind to target mRNA and knock it out as RNase H recognises and degrades the mRNA causing there to be no protein expression.
What is small interfering RNA?
The RNA-induced silencing complex (RISC) cleaves mRNA to degrade it, which reduces protein production and silences genes. Process called RNA interference.
Why would nucleic acid therapeutics require delivery vectors?
As they are relatively large molecules, -vely charged and unstable restricting their uptake into cells.
What are viral vectors and what are the advantages and disadvantages to their use for delivering nucleic acid therapeutics?
- viral vectors are a genetically modified virus where the genes involved in replication are removed and the new therapeutic gene is added.
- advantages: 1. High transfection efficiency (since viruses have developed the ability to be good at infecting cells) 2. Long term gene expression - some viral vectors integrate into the genome or persist in cells. 3. Targeted delivery - can be engineered to target specific cell types.
- disadvantages: 1. Safety concerns 2. Some viruses have limited cargo capacity. 3. Complex production - requires sophisticated manufacturing processes and bio safety containment.
What are non- viral vectors and what are the advantages and disadvantages to their use for delivering nucleic acid therapeutics?
- nano-particle (polymer or lipid) encapsulating nucleic acid.
- advantages: 1. Low immunogenicity - less likely to trigger an immune response, allowing repeated administration. 2. Simple and cost effective to produce. 3. No risk of insertion all mutagenesis as DNA doesn’t integrate into the genome. 4. Flexible cargo capacity with the ability to deliver large genes.
- disadvantages: 1. Lower transfection efficiency - typically less effective than viral vectors for gene delivery. 2. Gene expression is short lived. 3. Limited targeting ability - lacks mechanisms for cell specific delivery. 4. Potential toxicity at high dosages.
What are the challenges of nucleic acid therapy?
- delivery efficiency - nucleic acids are large -ve charged molecules that struggle to cross cell membranes. Effective delivery systems, such as lipid nanoparticles or viral vectors, are needed to ensure cellular uptake
• Stability and Degradation - Nucleic acids are prone to rapid degradation by nucleases in biological fluids. Chemical modifications and protective delivery vehicles help improve
• Immunogenicity and Safety - Some nucleic acid therapies can trigger immune responses, leading to inflammation or adverse effects.
• Targeting Specificity - Achieving precise delivery to target tissues or cells while minimizing off-target effects remains a major challenge.
• Manutacturing and Scalability - Producing high-purity, GMP-compliant nucleic acio therapies at scale is complex and costly, requiring specialized facilities and expertise.
• Patient Access and Cost - The high costs associated with development, manufacturing, and delivery can limit accessibility, particularly for rare disease treatments.
