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Advanced Drug Delivery > Gene Delivery And Therapy > Flashcards

Gene Delivery And Therapy Flashcards

1
Q

What does DNA encode?

A

Genetic information

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2
Q

Where is DNA located ?

A

Nucleus

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3
Q

What is a mutation?

A

A change in base pair sequence

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4
Q

How many coding genes do humans have?

A

20-25,000 coding genes

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5
Q

What is the function of H1 histone?

A

To package DNA into structural units called nucleosomes

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6
Q

What is chromatin?

A

A double-stranded helical structure of DNA

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7
Q

What are the main proteins in chromatin?

A

Histones

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8
Q

How do histones play a role in gene regulation?

A

DNA wraps around histones, therefore they play a role in gene regulation

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9
Q

What is a nucleosome?

A

Nucleosomes are the basic units of chromatin compaction

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10
Q

Roles of nucleosomes

A

Regulation of transcription
Regulation of replication
Cell reprogramming
DNA repair

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11
Q

Define gene therapy

A

Gene therapy is a technique that modifies a persons genes to treat or cure a disease.

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12
Q

Most common methods of gene therapy (3)

A
  1. Replacing a disease causing gene with a healthy copy of the gene
  2. Inactivate a disease causing gene that isn’t functioning properly
  3. Introducing a new gene into the body to help treat the disease
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13
Q

Barriers to non-viral gene delivery

A

Gene delivery vehicles can interact with plasma proteins or blood cells
They can aggregate and clog capillaries

Extravasation (leakage) into surrounding tissue can occur with leaky vasculature

Lysosomal degradation

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14
Q

List common gene delivery systems (8)

A

Biolistic delivery
Micro injection
Electroporation
Cationic polymers
Cationic liposomes
Cationic particles
Retroviral vectors
Adenoviral vectors

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15
Q

Describe how Cationic substances (polymers, liposomes, particles) deliver genes to the cells

A

Utilise negative charge on DNA and cell membrane
Mediate gene transfer gene transfer to membrane
Uptake by endocyctosis

(Positive carrier draws to negative cell membrane)

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16
Q

Describe how physical methods (electroporation, micro injection) deliver genes to the cell

A

Utilise penetration of cell and nuclear membrane

Electroporation & biolistic delivery penetrate cell membrane
Micro injection penetrates nuclear membrane

17
Q

Describe how virus-mediated delivery, delivers genes into a cell

A

Gene of interest (GOI) is encapsulated into a virus particle
Delivered into cell via receptor mediated endocytosis

18
Q

How does retroviral delivery differ from adenoviral delivery

A

For retroviral delivery, GOI enters the nucleus and integrates into the cell genome

For adenoviral delivery, GOI remains expressed in the cytoplasm

19
Q

What is LPLD?

A

Lipoprotein lipase deficiency
A rare, inherited genetic condition where there are increased levels of fat in the blood

20
Q

What conditions are associated with LPLD

A

Acute pancreatitis (inflammation of pancreas)
Lipemia (plasma appear milky due to high fat content)
Eruptive xanthomas (yellowish raised spots on skin which are fat deposits)

21
Q

What is Glybera?

A

Glybera is a gene therapy used for the treatment LPLD
It’s given as one administration

22
Q

What was the major downside of Glybera gene therapy?

A

Cost
$1.6 million per patient
Made it not commercially viable

23
Q

What are the reasons why you would use non-viral delivery

A

More biocompatible
High nucleic acid loading capacity - not restricted
Safer
Better transfection efficiency

24
Q

Describe what a lipoplexes is

A

Cationic liposome + DNA = lipoplexes

25
Q

What characteristics to lipoplexes show in vitro?

A

Protected from nuclear degradation
Lipoplexes trigger cellular uptake
Facilitates release of DNA
Excellent transfection efficiency

26
Q

What characteristics lipoplexes show in vivo?

A

Interaction with negatively charged blood components
Get trapped in mucous layers
Become embolised in capillaries

27
Q

What is the purpose of stealth liposomes?

A

Make liposomes less susceptible to phagocytes until the lipoplexes reaches the target

28
Q

Describe a method of stealth technology

A

Using PEG
PEG shielding until lipoplex reaches the target
PEG is removed when target is reached

29
Q

How does PEG work in stealth technology?

A

PEG coating appears to phagocytes as harmless
Forms an aqueous cloak around the lipoplex

30
Q

What is PEG?

A

A non-toxic, synthetic polymer used in stealth technology

It is hydrophilic and unable to interact with DNA or lipids

31
Q

List 1 pro and 1 con of using PEG

A

Pro - Provides longer blood circulation time

Con - There is dose dependant inhibition of transfection (preventing cell uptake of GOI)

Advanced Drug Delivery (18 decks)

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