This document provides an overview of gene therapy, including its history, approaches, delivery methods, applications, and challenges. Gene therapy involves introducing a normal gene into cells containing a defective gene in order to correct the underlying genetic disorder. It can be carried out in vivo by using viral vectors to deliver the therapeutic gene directly into patients, or in vitro by manipulating cells outside the body before reintroducing them. Many genetic diseases have been targeted, including immunodeficiencies, cancers, hemoglobinopathies, and rare diseases. While gene therapy holds promise, challenges remain such as short-lived effects, immune responses, and ethical concerns.

1. GENE THERAPY

2.  Gene
 Gene Therapy
 Approaches for gene therapy
 History
 How gene therapy is carried out?
 How it works?
 Delivery systems
 Different types of viruses used in gene therapy
vectors

3.  Non-viral Options
 Disadvantages of gene therapy
 Disease targets for Gene Therapy
oImmunodeficiency disorder
oVascular proliferative disorders
oLung Diseases
oLiver diseases
oSkeletal muscle
oHemoglobinopathies
oCancer
oOthers
oRare Disease Treated Using Gene
Therapy

4. GENES
Carried on chromosome
Basic unit of hereditary
Encode how to make protein
DNA>RNA>Protein
When gene altered cause
dysfunction of a protein

6. GENE THERAPY
 It is technique for correcting defective
genes that are responsible for disease
development
 Introduction of normal gene into cells
that contain defective gene to
reconstitute a missing protein product
 Is used to correct a definitive
phenotype so that sufficient amount of
a normal gene product are synthesized

7. Approaches for Gene Therapy
 A normal gene inserted to compensate
for a nonfunctional gene
 An abnormal gene traded for a normal
gene
 An abnormal gene repaired through
selective reverse mutation
 Change the regulation of gene pairs

8. HISTORY
 In 1980’s scientists began to look
into gene therapy
Insert human gene to bacterial cell
Bacterial cell would transcribe and
translate the information into protein
Then they would introduce the protein
into human cells

9. HOW GENE THERAPY IS CARRIED
OUT?
 Modification of somatic cell by
transferring desired gene sequence
into the genome
 Somatic cell necessary to ensure
that inserted genes are not carried
over to the next generation

10. How it works?
 A vector delivers the therapeutic gene
into a patient’s target cell
 The target cell become infected with the
viral vector
 The vector’s genetic material is
inserted into the target cell
 Functional protein are created from the
therapeutic gene causing the cell to
return to a normal state

13. Delivery systems
 In vivo:-
o Delivery of gene takes place in
the body
 In vitro:-
o Delivery takes place out of the
body and then cell are placed
back into the body

14.  In vivo technique use viral vector:-
– Virus = carrier of desired gene
– Virus is usually “crippled” to disable its
ability to cause disease
– Viral methods have proved to be the
most efficient to date
– Many viral vectors can stable integrate
the desired gene into the target cell’s
genome

15.  In vitro technique usually use
manipulation technique:-
– Electroporation
– Liposome
– Calcium phosphate
– Gold bullets (fired within helium pressurized
gun)
– Retrotransposons (jumping genes – early
days)
– Human artificial chromosomes

16. Different types of viruses used in
gene therapy vectors
 Retroviruses:-
A class of viruses that can
create double standard DNA
copies of their RNA genome
Copy of its genome can be
integrated into the chromosome
of host cell
HIV virus is retrovirus

18.  Adenovirus:-
A class of viruses with double
standard DNA genome that
cause respiratory, intestinal,
and eye infection in human
Virus that cause common cold
is adenovirus

19.  Adeno- associated virus:-
A class of small, single,
standard DNA viruses that can
insert their genetic material at a
specific site on chromosome 19

20.  Herpes simplex virus:-
A class of double standard DNA
viruses that infect a particular
cell type, neurons

21. Non-viral Options
 Direct introduction of therapeutic
DNA into target cells
 The creation of an artificial lipid
sphere with an aqueous core
 Chemically linking the DNA to a
molecule that will bind to special cell
receptors (less effective  )

22. Advantage of gene therapy
 Provide better treatment options for
cancer, AIDS and some hereditary
disease

23. Disadvantages of gene therapy
 Short-lived nature of gene therapy
 Immune response
 Problems with viral vectors
 Multigene disorders
 Ethical and legal problems
 Religious concerns

24. Disease targets for Gene Therapy
 Immunodeficiency disorder :-
For the treatment of congenital
immunodeficiency disorder
illustrate the use of ex vivo gene
transfer into hematopoietic stem cell
The three important
immunodeficiency syndrome that
use gene therapy are:-

25.  Adenosine deaminase deficiency:-
o First genetic diseases clinically treated
with gene therapy
o In children with this disorder leads to
the accumulation of deoxyadenosine
triphosphate that is toxic to lymphocyte
o It develop infections due to the
defective cell mediated and humoral
immune responses

26. Standard therapy is bone marrow
transplantation with periodic infusion of
PEG-ADA enzyme

27.  X- linked severe combined
immunodeficiency:-
Gene therapy for treating children with
X-SCID (sever combined
immunodeficiency) or the "bubble boy“
 Child is born with a very weal immune
system
Through this therapy, ADA is inserted
and then the genetically corrected cells
are transplanted back into the child

28. Vascular proliferative
disorders
 Atherosclerosis, restenosis after
angioplasty, and bypass-graft failure,
are leading causes of morbidity and
mortality
 Leads to up-regulated expression of
growth factors, cytokines, and
adhesion molecules by the vascular
smooth-muscle cells

30. Lung Diseases
 Several gene delivery vectors have
been applied to treating inherited
lung diseases
Cystic fibrosis:-
 Adeno-associated viral vector for
delivering CFTR are now in clinical
trials

31.  Alpha-1 Antitrypsin deficiency:-
It cause individual to pulmonary
emphysema and hepatic chirriosis
Recombinant alpha-1 antitrypsin
protein is commercially available for
human use

32. Liver diseases
 The liver can be afflicted with variety
of metabolic, infectious, and
neoplastic diseases for which
specific molecular intervention can
be envisioned

33. Skeletal muscle
 A variety of inherited disorder of
muscle including Duchenne
muscular dystrophy and the limb
girdle muscular dystrophies are
prime targets for the development of
gene based therapies
 Adeno- associated virus has been
demonstrated to be capable of
efficient and stable transduction of
adult skeletal muscle

34. Hemoglobinopathies
 Sickle cell disease and the
thalassemias are common single
gene disorders associated with
substantial morbidity and mortality
 These disorder should be amenable
to ex vivo gene transfer into
hematopoietic stem cells which then
would be used to reconstitute a
patient’s bone marrow

35. Cancer
 Multiple strategies have been
experimented with to treat different
kinds of cancer.
 These strategies include:-
 Oncolytic virotherapy
Suicide gene therapy
Therapeutic gene vaccines
Anti-angiogenesis

36.  Nanotechnology + gene therapy
yields treatment to torpedo cancer.
 A combination of two tumor
suppressing genes delivered in
lipid-based nanoparticles
drastically reduces the number
and size of human lung cancer
tumors

37. Others
 Chronic Granulomatus Disorder
(CGD),in which the process of ADA-
SCID is followed to help the patients
 In Hemophilia, the therapeutic gene
is introduced in the patient’s body to
cure it.

38.  Gene therapy is effectively used to
treat two adult patients for a disease
affecting no lymphocytic white blood
cells called myeloid cells
 Gene Therapy cures deafness in
guinea pigs. Thus gene therapy cure
deafness

39.  Neurodegenerative Diseases:-
Treatment of neurodegenerative
diseases such as Parkinson’s disease
and Huntington’s disease

40. Rare Disease Treated Using
Gene Therapy

41.  Brain scans of two boys with X-
linked adrenoleukodystrophy (ALD):-
The scans on the left (A) are from
a patient who received gene
therapy
 the one on the right (B) did not
The white areas represent the
brain damage caused by the
disease

42. The arrow on the left points to an
area that showed some damage,
but receded over the course of the
therapy
When gene therapy started, there
were a lot of predictions that this
was going to revolutionize
medicine. It's been a long time to
actually get it to work in humans"

43.  If the treatment for ALD holds up, it
might be the start of that revolution

44. http://www.wellesley.edu/Biology/Courses/219/Gen_news/i3_Gene_Therapy.jpg

47. Dr. BIKASH BHANDARI