1. What is the CRISPR/Cas9 Targeted
Genome Editing System?
What is Publicly Known about the
Use of this System in Humans?
Ignacio Monge and Maurits Vissers
(Fribourg, Switzerland)

2. Plan
• Maurits:
Origin and explanation of the CRISPR-Cas9 system
• Ignacio:
- One "ethically questionable" application in
"human embryos" in China
- One interesting development (in mice) without
apparent ethical problems
- Some quick general ethical ideas

3. CRISPR-Cas9

4. Bacteria can be attacked by viruses

5. Bacteria have developed a protection mechanism
(“a bacterial immune system”)

6. The basic concept: the bacterium keeps a copy of part
of the viral genome
Bacterial DNA
DNA
Viral-
Bacterial DNA

7. What is CRISPR-Cas9?
The copied sequence from the virus is used to guide the CRISPR-Cas9 complex to
the complementary viral DNA and to cut it!
Clustered Regularly Interspaced Short Palindromic Repeats
Bacterial Defense Mechanism

8. CRISPR-Cas9 system becomes an instrument for genome
editing:
example in mice

9. Tests on human embryos in China (1)

10. Tests on human embryos in China (2)
• Published in May 2015 (not in a big journal)
• They use tripronuclear zygotes (artificial
fecondation of an egg cell with 2 sperm cells)
=> they are not viable
• Use of the genome editing CRISPR/Cas9 approach
• Aim is to test the editing of the endogenous human
ß-globin gene

11. Tests in China (3) : results
• They manage to "reach", to cleave, the ß-globin
gene
• BUT
Ø There is mosaicism = embryos with different genetically
modified tissues
Ø Notable off-target effects (=mutations in other
unwanted places)
Ø Embryo cells also use other endogenous homologous
genes/sequences to repair the targeted gene (7 cases)
Ø In 4 cases, embryos with the targeted mutation (based
on designed injected ssDNA)
• Still far away from a secure clinical application !

12. Use of CRISPR/Cas9 for clinical
purposes without gene editing (1)

13. Use of CRISPR/Cas9 for clinical
purposes without gene editing (2)
• Salk Institute (California), Izpisua-Belmonte's lab
• Idea: activate the target genes without creating
genetic modifications
Ø recruitment of Cas9 and transcriptional activation
complexes by guide RNAs
Ø proof-of-concept: treatment of mouse-models of
diabetes, molecular dystrophy and acute kidney disease
Ø measurable phenotypes and amelioration of disease
symptoms
Ø new avenues for developing epigenetic therapies
against human diseases

14. The "Oviedo Convention" (1)
• Agreement from 1997
• A reference in the field of bioethics
• From the European council
Ø 34 out of 47 member countries have signed it
Ø Germany, Ireland, Malta and Monaco did not sign because
they refuse every manipulation of the human embryo (and)
abortion
Ø UK and Belgium neither, because they found it too restrictive
Ø 28 have ratified and applied it
• Not so easy to change

15. The "Oviedo Convention" (2)
• Article 13 – Interventions on the human genome
An intervention seeking to modify the human genome may
only be undertaken for preventive, diagnostic or therapeutic
purposes and only if its aim is not to introduce any
modification in the genome of any descendants.
• Article 18 – Research on embryos in vitro
1 Where the law allows research on embryos in vitro, it
shall ensure adequate protection of the embryo.
2 The creation of human embryos for research purposes is
prohibited.

16. Possible mid- and longterm
purposes of gene editing
• CLINICAL 1: genetically heal embryos from parents that
are carriers of genetic diseases?
=> this is rather unrealistic, because in vitro fertilization (IVF) is
being used and healthy embryos can be chosen by genetic
diagnosis anyway (which is already a problem, ethically speaking)
• CLINICAL 2: genetically heal tissues from an adult
patient, or stem cells, and reintroduce them back to the
patient, avoiding to cause heritable genetic changes if
possible (this is ethically less of a problem, if the stem
cells do not come from embryos)
• CLINICAL 3: "epigenetic approach" for illness treatment
• GENETIC DESIGN: "sculpturing" of humans to a lineage
that is physically and intellectually "stronger and
smarter"

17. Some general ethical reflections
• The question of tolerance towards handicapped
persons
• Kant: the universal principle for ethics
Consider the other person as an "aim in
his/herself" and not as an instrument that I use,
that I manipulate
= as a mean (for my profit)
=> Consider other human beings as persons, having
rights, and not reducing them to an object, that
has no rights

18. Programmed molecular robots
and automation of genomic modification
• The CRISPR/Cas9 system allows to direct through
the guide RNA a "genomic editing machine" or a
"gene activating machine" to target genes
• After the genome sequencing era (genomes of
humans and many organisms have been read
through automated mechanisms), a new era of
genome modification could be opened, in the mid
or long term, also through automated processes

19. Bibliography
• 2 cited scientific articles
• Wikipedia
• Website "Genethique"
• Aceprensa