Medical Biotechnology towards Clinical Practice
(MOL104 & MIN13)
September 2021 – November 2021
1. Medical Biotechnology and Vaccines
2. Gene modification: Transfection & Transduction
3. NA (Genetic engineering)
4. NA (Stem cells)
5. Introduction to Genetic Therapy
6. Disease Examples and Treatment Strategies
7. Molecular Tumor Genetics
8. Identification of chromosomal aberrations in tumors
9. Gene therapy using viral vectors
10. Viral Gene therapy for Retinal diseases
11. Biologics drug development: Discovery and development of Therapeutic Antibodies
12. Biologics drug development: Discovery and development of Therapeutic Antibodies (last
parts missing)
13. Introduction legal and ethical issues
14. CRISPR/Cas-Mediated Genome Editing
15. Introduction to Tissue Engineering
16. The extracellular matrix and scaffolds for tissue engineering
17. Immune regulation and Immunotherapy
18. Immunotherapy of cancer
,Lecture 1 – Medical Biotechnology and Vaccines
Even 2000 BC, herbs and spices, potions and powder were used by people. In 1796, the first vaccine
by Edward Jenner was discovered, cowpox that protects from smallpox. In 1922, the hormone insulin
was discovered, in 1928 antibiotics by Alexander Fleming were found. The HeLa cell culturing originates
from 1951.
Developing a new medicine takes an average of 10-15 years. Of the tens of thousands of compounds
screened, only one is approved. The road to approval looks as followed: Basic research – Drug discovery
– Pre-clinical – (IND submitted) – Clinical trials Phase 1-3 – (NDA/BLA submitted) – FDA review – (FDA
approval with only 1 FDA approved medicine) – Post-approval research & monitoring phase 4. More
than 7000 medicines are in development globally, ranging from 400 against diabetes to 1900 against
cancer. The two main biologic medicines product categories in development are monoclonal
antibodies (mAb) and vaccines. There are 258 vaccines in development to prevent and treat diseases
such as 2 for Alzheimer, ranging to 125 against infectious diseases. The power of vaccines in the last
decades have shown how diseases such as diphtheria, polio, measles and meningococcus can be
completely eliminated.
Vaccine strategies
1. Heat killed or formalin-inactivated vaccine. A pathogen is treated with heat or chemicals, resulting
in its death, while the antigenicity is retained. It is administered, and the vaccine stimulates
immunity, but the pathogen cannot multiply. If the pathogen is not fully killed, it can lead to serious
safety concerns. It is the least safe, but one of the most effective ways.
2. Live attenuated vaccines. In live attenuated cells or viruses, the virulence is eliminated or reduced,
resulting in a pathogen that is alive with the same antigenicity. It is administered, and the vaccine
stimulate immunity (via its antigens), the pathogen can multiply. Creating an attenuated strain
takes time and safety checks, but it is the most effective type of vaccine.
, 3. Vector vaccines. Vaccina viruses like the poxvirus have a broad
host range and are stable (lyophilized). They are well studied
dsDNA (187 kbp) with around 200 proteins. The adenovirus is a
dsDNA (26-46 kbp) with around 23-46 proteins. By using a virus
which is able to infect humans, but is harmless by itself, epitopes
can be mounted on top of that virus and it is able to infect cells,
that will start fighting it. This is done via recombinant technology.
The Johnson vaccine uses an adenovirus with a covid spike
protein, it is a harmless virus not able to replicate, but will show
the body how to mount an immune response against said spike
protein. Adenoviruses are easier to work with than Pox viruses,
due to their huge genome.
4. Subunit vaccines. A part of a
pathogen is isolated in a
mixture which is used to inject
into the organism in order to
show it to the immune system.
This type of vaccine is already
safer; however, it is less
efficient as it is not presented in
a viral-like matter, but only as a
protein. Recombinant
technologies are used.
5. Peptide vaccines. Requirements for this vaccine are the presence of
an epitope (short stretch of continuous residues), that should exist
in a living pathogen, and the peptide conformation should mimick
the strcuture in the intact pathogen. They are chemically
synthesized proteins, and are produced quicker as they do not need
cell lines that produce recombinant proteins. However, a single
epitope might not be sufficeintly immunogenic, since even less
epitopes can be used by the immune system.
6. DNA & RNA
vaccines. These vaccines do not contain anything
virus-like, the DNA and RNA lead to the cell
producing the viral proteins themselves. A few years
ago, the vaccines were not very efficient, since no
alarming signal was sent to the body. Now, it is
possible to generate very stable RNA via changed
nucleotides (uridine to pseudouridine). They can be
packaged into nanoparticles that can easily be taken
up by the body. It is now one of the safest and most effective vaccines. However, the effectiveness
is related to how non-self an epitope is, a cancer protein with just a few changed will not be as
effective as the covid spike protein.
, Lecture 2 – Gene modification: Transfection & Transduction
Genetic modification
During episomal addition, DNA is being added
which is not part of the genome. It is transient
(short-lived) and gets destroyed. When
introducing DNA, it has to be integrated into
the genome, or there needs to be an
overruling argument so that it is maintained by
the cell. Plasmids usually have resistance
providing enzymes. A stable modification is
either random or targeted. Wit random
mutations, the danger of insertional
mutagenesis occurs, the sudden strange part
of DNA might destroy the functionality of an
important DNA part. When it is targeted, it
needs to be made sure that almost perfect homology exists, and it is incorporated in such a way that
no potentially harmful response gets triggered.
Expression construct
Usually, plasmids are used when
introducing a transgene. Plasmids are
two faced molecules, one side
responsible for propagation in
bacteria, and the other side for
expression in mammalian cells.
Different surroundings for these
structures are required, as prokaryotes
and eukaryotes contain different
systems.
Transfection methods
Physical:
Micro-injection (transgenic mice) – The DNA is injected into the nucleus. With this method, not a large
number of cells can be injected. Even very little amounts of injected volume contain millions of DNA
copies, leading to insertional mutagenesis, it is unpredictable, and sometimes the cells are able to
sense a wrong piece of DNA. This method is not widely used anymore, as it is never known what it will
yield.
Electroporation (KO/ knock-in mice) – A cuvette with suspended cells and DNA present around it is
exposed to an electric field. Due to this, the membranes are mixed up, resulting in pores, and the DNA
is able to enter. This method is very efficient, and due to the concentration of DNA, only a small amount
is able to enter the cell.
Particle bombardment (plants, genetic vaccination) – Due to the plant cell wall, using electroporation
is not an option. By use of helium pressure, gold particles are aimed at and taken up by the cell. With
it, DNA is brought along as well. However, the possible number of cells is limited. This method can also
