Historically, genetic toxicology has been comprised of bacterial and cell based in vitro assays such as the Ames assay (a bacterial mutagenicity assay), Micronucleus and Chromosomal Aberration assays (mammalian cytogenetic assays), and Mouse Lymphoma Assay (in vitro mammalian cell gene mutation assay). These were routinely used for safety evaluation and are still part of the standard core battery. The emergence of new technologies has facilitated the development of in vitro methods for safe and effective drug and chemical testing. This BioReliance® toxicology services webinar will explore alternative models, including 3D skin models that comply with the EC Scientific Committee on Consumer Safety (SCCS) recommendations. It will also discuss how the 3Rs (Replace, Reduce, Refine) Principle advocates the exploration of such alternative methods while achieving required goals. In this webinar, you will learn: • About in vitro alternatives to animal toxicity testing in pharma, chemical, tobacco, and personal care products. • How the 3Rs (Replace, Reduce, Refine) Principle advocates exploring alternative methods without compromising the required goals. • Alternatives to comply with the 7th Amendment to the EC Cosmetics Directive.

1. Merck KGaA
Darmstadt, Germany
Javed A. Bhalli
Associate Director – BioReliance® Genetic Toxicology
Services
01 February 2018
In Vitro
Alternatives in
Toxicology

2. The life science business of
Merck KGaA, Darmstadt, Germany
operates as MilliporeSigma
in the U.S. and Canada.
2

3. What is Toxicology?
The science of poisons……
• “The adverse effects of chemical substances on living
organisms”
• An interdisciplinary science overlapping with;
Biology, Chemistry, Pharmacology, and Medicine
• The relationship between dose and its effect on the exposed
organism
3

4. … the study of chemical, physical or biological agents that can
change the sequence or structure of DNA
What is Genetic Toxicology?
DNA damage can be:
• at nucleotide or at chromosomal level
• induced by direct mechanisms (chemical
or metabolite interacts with DNA)
• induced by indirect mechanisms (chemical
or metabolite affects other cellular
macromolecules, e.g. mitotic spindle
fibers)
4

5. AT AG
Mutation
Chromosome Break
Misrepair
or No Repair
Chromosome
Aberration
DNA Damage
What is Genetic Toxicology?
Error Free Repair
or Apoptosis,
Cell Death
No Genotoxicity
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6. Objective of Genetic Toxicology Testing – Risk Assessment
Hazard Identification
Can the test article cause injury?
Exposure Assessment
What is the dose?
Risk Assessment
What is the probability of injury?
Risk Management
What should be done about it?
Historically, gene-tox data
have been used in hazard
identification
• Can the test material cause
mutations?
• Binary outcome: Yes or no
More recently, gene-tox
data have been evaluated
using quantitative
approaches to generate
probability estimates for
guiding risk management
decisions
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7. DISCOVERY DEVELOPMENT COMMERCIALIZATION
Antibody Products &
Research Models
Pathology, Genetic Toxicology, In Vivo
Pharmacology
Toxicology, and Safety Pharmacology
Biomarkers/Genomics
Clinical Pharmacology
Clinical Development
Market Access
Central Laboratories
Bioanalytical Small & Large Molecule, Biopharmaceutical, Drug Metabolism & Pharmacokinetics,
Immunology & Vaccines, CMC Pharmaceutical Development Services, Environmental Sciences
Regulatory Affairs
Research Pre-Clinical Phase I Phase II Phase III Phase IV
Drug Development Paradigm
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8. Commonly used Genotoxicity Assays and their Endpoints
Assay
Mutation
Point Mutations
Structural chromosome
aberrations
Numerical chromosome
aberrations
Ames Assay X
Micronucleus Assay X X
Chrom Abb Assay X X
Mouse Lymphoma
Assay
X X
Comet Assay --- DNA strand breakage ---
TGR Assay X
Pig-a Assay X
ICH Core
Battery
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9. Three Assays;
Two Options;
Option 1: Two in vitro + one in vivo assay
• Ames Assay
• Cytogenetic Assay (MN/Chrom Ab/MLA)
• In vivo MN assay
Option 2: One in vitro + two in vivo assays
• Ames Assay
• In vivo MN assay
• Second in vivo assay in a tissue other than bone marrow – Comet Assay
International Regulatory Guidelines
International Conference on Harmonization (ICH)
In Vitro Alternatives - 01 Feb 20189

10. International Regulatory Guidelines
If intake in diet is > 1.5 µg/day --- Conduct ICH battery
If intake in diet is < 1.5 µg/day --- Only in vitro assays
Regulations listed in Redbook 2000 (2007)
Center for Food Safety and Applied Nutrition (CFSAN)
European Food Safety Authority (EFSA)
10

11. Registration, Evaluation, Authorization and Restriction of Chemicals (REACH)
Volume Tiers
Annual
Tonnage
Registration
Year
Annex Genetic Toxicology Testing
1-10 2018 VII
• Ames
• If positive, move to Annex VIII
10-100 2018 VIII
• Ames
• In vitro cytogenetic
• If negative, in vitro mammalian gene mutation assay
(MLA/HPRT)
• If positive, move to Annex IX and X
100-1000 2013 IX
• Ames
• In vitro cytogenetic
• If negative, in vitro mammalian mutation
• If positive, in vivo test
• If negative, second in vivo test
• If positive, germ cell mutagenicity test
>1000 2010 X
International Regulatory Guidelines
Regulation of the European Union
Promotes alternative methods to reduce the use of animals
European Chemical Agency (ECHA) implements regulations
11

13. 3Rs Principle
Russell and Burch (1959) “The principles of humane experimental technique”
Reduction
 Reduce the use of animals in life science research
 Use of in vitro cell culture for early stage screening
 Human hepatocyte culture - ADME
 Effects of compounds on embryo development - in vitro embryonic stem cell culture
 Integration of endpoints
Refinement
 Refining and improving processes to minimize pain and stress
 Study results can vary if the animals are stressed
 Euthanex® - Quick and painless Euthanasia of small lab animals
 Refined and less stressful bleeding techniques
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14. Replacement
 In vitro cell cultures
 In vitro 3D reconstructed models (EpidermTM
, EpiAirwayTM
)
 Computer models (DEREK, Leadscope)
 Example - Insulin
3Rs Principle
14

15. Standard in vitro Approaches
1. Gene Mutation Assays:
• Ames Assay – Bacterial reverse mutation, S. Typhimurium/E.coli
• Mouse Lymphoma Assay –TK gene, L5178Y cell line
• HPRT Assay –Hprt gene, CHO/L5178Y/TK6 cell lines
• In vitro Pig-a Assay – Pig-a gene, GPI deficient cells, L5178Y/TK6 cell lines
2. In vitro chromosome damage assays:
• Micronucleus Assay – HPBL, TK6, CHO cell lines, Flow or Microscope
• Chrmosomal Aberration Assay – HPBL, CHO cell lines, Microscope
3. Others:
• Neutral Red Uptake (NRU) – Cytotoxicity assay
• Bhas – Cell transformation assay
• SHE - Cell transformation assay
15

16. • European Union (EU) 7th Amendment to the Cosmetics Directive adopted
2003
• Prohibits animal use for genotoxicity testing as of March 2009 for ingredients
used in cosmetics marketed in EU
• In vivo assays not practical with large scale testing programs (e.g. REACH)
• Do not comply with the 3Rs principle: Replace, Reduce, Refine
• Industry needs to comply with regulations
What is the approach for cosmetic ingredients that are positive in in vitro genotoxicity
testing battery?
In Vivo Genotoxicity Testing of Cosmetics
16

17. Genotoxicity Testing in 3D Tissue Models: A Novel
Approach For Replacement of In Vivo Testing
Genotoxicity Testing in 3D
Tissue Models
• 3D Reconstructed Human Skin
Models for Cosmetic Ingredients
In vitro genotoxicity assays
In vivo genotoxicity assays
17

18. • More natural cell-cell interactions
• Show human ‘in-vivo like’ behavior for key parameters like cell viability,
proliferation, metabolism, function
• Skin is the tissue with the highest exposure to cosmetics (also many
chemicals, drugs)
• Better representation of real-life exposure
• Use of skin-based assays becoming standard for other endpoints
(irritation, corrosion)
Advantages of Human 3D Skin Models
18

19. Stratum corneum;
dead keratinocytes
3D Reconstructed Human Skin Model
EpiDermTM
• Commercially available
• Highly differentiated 3D tissue models
• Normal human-derived epidermal keratinocytes (NHEK)
• Cells grown on culture inserts at air-liquid interface that causes cell differentiation
• Widely used in industry
Cross Section of EpiDermTM Model (image source - MatTek)
Stratum spinosum;
keratinocytes
Stratum basale;
Keratinocyte stem cells
19

20. EpiDermTM Metabolic Capability
EpiDermTM metabolic capacity appears similar to human skin
– Aromatic amines (e.g. PPD, PAP) are N-acetylated in EpiDermTM as occurs in human skin
(Hu et al., Tox. Lett., 188: 2009)
– Expression of xenobiotic metabolism genes in EpiDermTM is similar to human skin
(Hu et al., Tox. In Vitro, 24: 1450-1463, 2010)
– Activity of metabolism enzymes established by Cosmetics Europe (CosEU)
(Götz et al., Exp. Derm., 21: 364-369, 2012)
– Predominance of phase 2 detoxification pathways over phase 1 activities consistent with skin
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21. 3D Skin Micronucleus Assay
• Provides comprehensive basis for investigating chromosome (clastogens) or spindle fiber
damaging agents (aneugens)
• Small, nuclear membrane enclosed chromosome/chromosome fragment(s) formed from
damaged chromosomes
• Regulatory accepted endpoint worldwide (OECD 487, 2016)
• Analysis is easy, therefore increased inter-laboratory transferability
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22. 3D Skin Micronucleus Assay
-24 Hours
Tissues arrival,
feeding with
media,
incubation @
37°C
0 Hours 24 Hours 48 Hours 72 Hours
Cells
harvested,
slides
prepared,
stained &
scored
 Tissues refed daily with fresh media containing
Cytochalasin-B, dosed with test article for three
consecutive days, incubation @ 37°C
22

23. Preliminary Cytotoxicity Assay
• Tissues are dosed for three days (15 tissues: 1 VC, 14 TA)
• All doses are in single replicates
Definitive Assay
• Tissues are dosed for three days (30 tissues: 1 VC, 7 TA, 2 PC)
• All doses are in triplicate
• Cytotoxicity is determined by slide scoring for CBPI
• Concentrations for MN scoring are selected based on cytotoxicity
• Binucleated cells with micronuclei (BNMN) are scored
Confirmatory Assay
• Performed only if Definitive Assay is negative
• Same design as for Definitive
3D Skin Micronucleus Assay
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24. Analysis of micronuclei
Cell fixation/acridine
orange staining
Curren et al., Mut. Res. 607: 192-204, 2006
Dahl et al., Mut. Res. 720: 42, 2011
Gentle trypsinization to collect basal
keratinocytes
Application of test article
3D Skin Micronucleus Assay
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25. • Commercially Available
• Phenion®
Full-Thickness (FT) Skin Model
• Contains dermal and epidermal layer
• DNA damage is determined separately for both layers
Image source: Phenion.com
3D Skin Comet Assay
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26. Preliminary Cytotoxicity Assay
• Tissues are dosed for three days (12 tissues: 1 VC, 11 TA)
• All doses are in single replicates
• 3 cytotoxicity parameters (Adenylate Kinase (AK), Adenosine Triphosphate (ATP), Protein content)
Definitive Assay
• Tissues are dosed for three days (36 tissues: 1 VC, 9 TA, 2 PC)
• All doses are in triplicate
• 3 cytotoxicity parameters are performed
• Dose levels selected based on cytotoxicity
• Comet slides prepared and scored
Confirmatory Assay
• Performed only if Definitive Assay is negative
• Tissues are dosed for three days (45 tissues: 2 VC, 9 TA, 4 PC)
• Vehicle and positive controls with and without Aphidocolin (APC)
3D Skin Comet Assay
26

27. Day 1
Dishes refed
Tissues are dosed
with vehicle and
test article
Day 2
Tissues are dosed
with vehicle and
test article
Day 3
Tissues are dosed
with vehicle and
test article
Tissues are dosed
with positive control
(if applicable)
Prepare Comet
Slides
Measure AK
Day 4
Tissues are
Homogenized
Protein contents
are measured
ATP level is
measured
Day 5
Slides are prepared
Electrophoresis is
conducted
3D Skin Comet Assay
27

28. 3D Skin Comet Assay
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29. 3D Skin Comet Assay
29

30. Ciliated apical
surface
Mucociliary
epithelium
Microporous
membrane
Courtesy of MatTek corporation
• 3D Reconstructed EpiAirway Models
• Used in Tobacco research and Inhalation studies
• 3D EpiAirway
TM
– developed in 2000
• 3D MuciliAir
TM
– developed in 2006
•
3D EpiAirway (EpiAirwayTM
)
30

31. Advantages of Human 3D EpiAirway Models
• Differentiated structure and functions
• Barriers properties, cilia formation, mucous etc
• Air-liquid interface (ALI) – Apical or systemic treatment
• Individual variability
• Asthma
• COPD
• Smoking history
• No functional defects like immortal cell lines (e.g. p53)
• Avoid species difference
• Cells of human origin – no inter-species extrapolation
• Can better model human disease – asthma/COPD
• No ethical issues related to animal testing
31

32. • Applications in Toxicology;
• Remain fully differentiated and functional for over a year
• Ready and easy to use
• Real life exposure conditions
• Xenobiotic metabolizing capabilities
• Tissue of choice for Tobacco research
• Tissues are exposed to whole smoke
• Cytotoxicity is determined by cilia beating movement
• Cigarette smoke/E-cigarettes
• Airborne particulates
• Chemicals
• Pharmaceuticals
• Consumer products
• Nanotoxicology
3D EpiAirway (EpiAirwayTM
)
32

33. 3D EpiAirway (EpiAirwayTM
)
33

34. • In order to place 10 different groups in 4 positions of Benzene ring - 10
4
• Synthesize small number of compounds - predict biological activity of related compounds
• Quantitative Structure Activity Relationship (QSAR) is a mathematical relationship
• between biological activity and geometric & chemical characteristics
• Models are used to predict biological activity of the drug molecule
• QSAR is useful in predicting carcinogenicity of drug molecules
• Promising molecules can be taken into wet-lab experiments
• DEREK and Leadscope are more widely used to predict DNA reactivity
• CADD is used to predict the receptor binding site for the drug molecule
In silico Models
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35. • Multichannel 3D microfluidic cell culture chip
• Stimulates the activities, mechanisms, physiological
response of entire organs
• Translucent micro devises,
• Capability to watch inner workings of human organs
• To develop all different human organs on chip
• Examples - lung, liver, heart, bone marrow, kidney
etc…
Liver Lung Heart Bone Marrow
Organ on Chip
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36. How these organs on chip can help the pharmaceutical
industry
• To replace animal models
• Pharmacological studies, ADME
• Comparison studies of drugs on human and animals
• Interaction of pathogens and organ cells
• Mechanism of virus attacks
• Effect of drug on its main site of action and other organs
• Toxicology of drugs and cosmetics
• To predict affective and safer human dose
Organ on Chip
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37. Human on Chip
• Organ on chip is an innovative technology
• Will help in drug development and New drug discoveries
• Can revolutionize the pharmacy field in the future??
37

38. THANK YOU!
38

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owners. Detailed information on trademarks is available via publicly accessible resources.
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