W/S 5 - Liver toxicology models Flashcards

1
Q

elements of organ-on chip

A

Microfluidic channels - nutrient, oxygen and waste exchange (made with PDMS = flexible)

Cells of target organ

Extracellular matrix - scaffold for cell attachment

Stimulate physical forces experienced by tissue

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2
Q

[Ewart et al, 2022] experiment

A

tested 27 drugs on 780 liver chips

80% sensitivity

100% specificity

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3
Q

[Ewart et al, 2022] how they measured liver toxicology

A

reduced albumin and ALT production via qRT-PCR

increase in cytokine and immune cell activation

+ immunofluorescence images of cell imaging

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4
Q

[Ewart et al, 2022] what cells did they use?

A

liver sinusoidal endothelial cells

kupffer cells

stellate cells

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5
Q

immune cells and liver function

A

kupffer cells (= macrophages in liver), natural killer cells, dendritic cells, T cells

become activated when liver encounters toxic substance

release pro-inflammatory cytokines (e.g. TNF, IL-6)

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6
Q

advantages of organ-on chips

A

Save money as better at predicting if drug will fail
- Divert more resources into drugs which are more likely to be successful

Use of human tissue - more translatable

High throughput capability

Ethical - no animals used

Accounts for donor variability (multiple donors used) - e.g. people’s diets, race/ethnicity

Customizable in what cell types you see in models

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7
Q

disadvantages of organ-on chips

A

If donor has polymorphism that drug will respond to in different way
- Donor genetics may not be relevant to wider population and polymorphisms could contribute to different drug responses

Only been shown for small molecules

Not 100% accurate

Doesn’t fully represent organ complexity - example - Pemoline couldn’t be tested because toxicity is due to immune cells, which were not included

Requires high level of expertise, not yet taken up by big drug companies as it takes lots of time to optimize

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8
Q

selectivity

A

ability to distinguish between hepatoxic and non-toxic drugs

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9
Q

specificity

A

ability to avoid false-positive predictions

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10
Q

[Yang et al, 2023] - why they decided to develop organ-on chips

A

1/3 of drugs removed from market due to liver damage

1/2 drug candidates induce hepatotoxicity in humans but not animals

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11
Q

[Yang et al, 2023] - fialuridine

A

potential hepatitis B therapy

induced severe toxic reaction and hepatic failure in humans (animal model data didn’t indicate this)

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12
Q

advantages of monolayer culture

A

low cost

easy to obtain

simple to culture

fast prep

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13
Q

disadvantages of monolayer culture

A

single cell type

no cell-cell or cell-ECM interaction

limited culture time

incomplete metabolic function

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14
Q

what are spheroids?

A

collection of cells that form spheroid shape

can be made from multiple cell types

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15
Q

[Yang et al, 2023] - flucloxacillin

A

converted to 5-hydroxymethyl metabolites by CYP3A4

= toxic to biliary epithelial cells but not hepatocytes

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16
Q

advantages of spheroids

A

increased toxic sensitivity

easy of use protocol

long-term culture

reproducibility

17
Q

disadvantages of spheroids

A

varied physiological response

limited by type of input cell

simplified architecture

18
Q

what are organoids?

A

differentiating stem cells which reorganise themselves into 3D structure

19
Q

[Shinozawa et al, 2021] - experiment

A

treated HLOs with 238 market drugs

88.7% sensitivity and 88.9% specificity

20
Q

advantages of organoids

A

mimic physiological architecture

replicate key hepatic functions

long-term culture

multi-cell type interaction

21
Q

disadvantages of organoids

A

fetal-like phenotype

high data variability

difficulty in data processing

high cost

sometimes uneven in form/size - unanticipated fluctuations in results

22
Q

[Zhang et al, 2019] - experiment

A

paired their HLO with liver-on-a-chip

= greater ability to predict hepatotoxicity