The document discusses gene therapy, including its introduction, types, approaches, and advancements. It covers somatic and germ cell therapies, ex vivo and in vivo methods, and various vectors used for gene delivery. Recent breakthroughs in gene therapy, particularly in treating conditions like sickle-cell disease and restoring vision, highlight the progress in this medical field.

1. GENE
THERAPY
PRESENTED BY,
PAVAN K A
M.PHARM, PHARMACOLOGY
COPS, DAYANANDA SAGAR UNIVERSTY
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2. CONTENTS
• Introduction
• Approaches
• Types of Gene Therapy
• Vectors used in gene therapy
• Applications
• Recent advancements in gene therapy
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3. INTRODUCTION
• Gene therapy is the process of inserting genes into cells
to prevent, treat or cure wide range of diseases.
• Gene therapy primarily involves genetic manipulations in
animals or humans to correct a disease.
• Gene augmentation therapy: a DNA is inserted into the
Genome to replace the missing gene product.
• Gene inhibition therapy: the antisense gene inhibits the
expression of the dominant gene.
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6. Somatic cell gene therapy Germ cell gene therapy
• Non reproductive cell / Somatic
cells. These are the cells of an
organism other than sperm or
egg cells, e.g., bone marrow
cells, blood cells, skin cells,
intestinal cells.
• somatic cell gene therapy
involves the insertion of a fully
functional and expressible gene
into a target somatic cell to
correct a genetic disease
permanently.
• The genetic alterations in
somatic cells are not carried to
the next generations. Therefore,
somatic cell gene therapy is
preferred .
• The reproductive (sex) cells of
an organism constitute germ
cell line.
• Gene therapy involving the
introduction of DNA into germ
cells is passed on to the
successive generation.
• For safety, ethical and
technical reasons, germ cell
gene therapy is not being
attempted at present.
Approaches in gene therapy
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7. TYPES OF GENE THERAPY
• Ex vivo gene therapy : This involves the transfer of
genes in cultured cells (ex: bone marrow cells)
which are then reintroduced into the Patient.
• In vivo gene therapy : The direct Transfer of
genes into the cells of a particular tissue is
referred to as in vivo gene therapy.
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8. EX-VIVO GENE THERAPY
• The ex vivo gene therapy can be applied to only
selected tissues (e.g., bone marrow) whose cells can
be cultured in the laboratory.
• Steps involved
1.lsolate cells with genetic defect from a patient.
2.Grow the cells in culture.
3.Introduce the therapeutic gene to correct gene defect.
4.Select the genetically corrected cells (stable
transformants) and grow.
5.Transplant the modified cells to the patient.
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9. THE FIRST HUMAN GENE THERAPY
• National Institutes of Health in Bethesda, Maryland, in
1990, Performed on a 4yr old girl Ashanthi DeSilva.
suffering from SCID- Severe Combined Immunodeficiency.
Caused due to defect in gene coding for ADA. Deoxy
adenosine accumulate and destroys T lymphocytes.
Disrupts immunity , suffer from infectious diseases and die
at young age. Correct the deficiency of enzyme, Adenosine
deaminase (ADA).
• Bone marrow cells from the child were transformed with an
engineered retrovirus containing a functional ADA gene.
• The treated cells were reintroduced into the patient’s
marrow. Four years later, the child was leading a normal life
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10. • synthetic ADA was administered in a complex with
polyethylene glycol (PEG). For many ADA-SCID
patients, injection of the ADA-PEG complex allowed
some immune system development, with weight gain
and reduced infection, although not full immune
reconstitution.
• trial participants received both treatments at once,
making it unclear which treatment was primarily
responsible for the positive clinical outcome.
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11. IN-VIVO GENE THERAPY
• The direct delivery of the therapeutic gene (DNA) into
the target cells of a particular tissue of a patient
constitutes in vivo gene therapy.
• Many tissues are the potential candidates for this
approach. These include liver, muscle, skin, spleen,
lung, brain and blood cells.
• Gene delivery can be carried out by viral or nonviral
vector systems.
• It can be the only possible option in patients where
individual cells cannot be cultured in vitro in sufficient
numbers (e.g. brain cells).
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12. • In vivo gene transfer is necessary when cultured cells
cannot be re-implanted in patients effectively.
• The success of in vivo gene therapy mostly depends
on the following parameters.
• The efficiency of the uptake of the remedial
(therapeutic) gene by the target cells.
• lntracellular degradation of the gene and its
uptake by nucleus.
• The expression capability of the gene.
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13. EXAMPLE:
• In patients with cystic fibrosis, a protein called cystic
fibrosis transmembrane regulator (CFTR) is absent due to
a gene defect.
• In the absence of CFTR chloride ions concentrate within
the cells and it draws water from surrounding.
• This leads to the accumulation of sticky mucous in
respiratory tract and lungs.
• treated by in vivo replacement of defective gene by
adenovirus vector .
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14. VECTORS IN GENE THERAPY
• The carrier particles or molecules used to deliver
genes to somatic cells are referred to as vectors.
• 2 main classes
• Viral vectors
• Non viral vectors
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15. VIRAL VECTORS
• The vectors frequently used in gene therapy are viruses,
particularly retroviruses. RNA is the genetic material in
retroviruses. As the retrovirus enters the host cell, it
synthesizes DNA from RNA (by reverse transcription). The
so formed viral DNA (referred to as provirus)gets
incorporated into the DNA of the host cell.
• Risk Factor: some of the retroviruses can convert normal
cells into cancerous ones. Therefore, it is absolutely
essential to ensure that such a thing does not happen.
• Many viral vector systems have been developed for gene
delivery These include retroviruses, adenoviruses, adeno-
associated viruses and herpes simplex virus.
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16. NON VIRAL VECTORS
• There are certain limitations in using viral vectors in
gene therapy. In addition to the prohibitive cost of
maintaining the viruses, the viral proteins often induce
inflammatory responses in the host.
• Pure DNA constructs that can be directly
introduced into target tissues.
• Lipoplexes, lipid-DNA complexes that have DNA
surrounded by lipid layers.
• Human artificial chromosome which can carry
large DNA (one or more therapeutic genes).
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17. CLINICAL APPLICATIONS
Bone repair:
Bone loss caused by trauma, neoplasia, reconstructive surgery, congenital
defects or periodontal disease is a major worldwide health problem. The
bone morphogenic proteins (BMPs) enable skeletal tissue formation during
embryogenesis, growth, adulthood, and healing. Probably BMPs (BMPs 2,
4 and 7) are the only growth factors which can singly induce de novo bone
formation both in vitro and at heterotopic sites. Bone defects in the oral and
maxillofacial region can be repaired by transferring genes encoding BMP‘s .
Oral Cancer:
The general strategy in cancer treatment is to express a gene product that
will result in cancer cell death. It can be achieved by Addition of a tumor-
suppressor gene, Deletion of a defective tumor gene, Introduction of genes
to inhibit tumor angiogenesis and "Cancer vaccination" with genes for
tumor antigens.
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18. • Gene therapy to grow new teeth: This approach is generally
presented in terms of adding molecules to induce de novo tooth
initiation in the mouth. It might be combined with gene-
manipulated tooth regeneration; that is, endogenous dental cells
in situ can be activated or repressed by a gene-delivery technique
to produce a tooth. More than 200 genes are known to be
expressed during tooth development.
• Cardiac disease: Gene therapy has been investigated to target
angiogenesis ( the formation of new blood vessels) during cardiac
surgery and to improve calcium handling mechanism in heart
failure.
• Infectious disease: gene therapy vaccines are being developed
and trailed for tackling infectious diseases including tuberculosis,
malaria, HIV and influenza.
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19. RECENT ADVANCEMENTS IN GENE THERAPY
2017 Was the Year of Gene-Therapy Breakthroughs
• Sickle-cell cure
In March, researchers announced that a teenage boy in France
had been cured of sickle-cell disease after receiving an
experimental gene therapy developed by Bluebird Bio. Scientists
removed stem cells from the boy’s bone marrow and modified
them in the lab by introducing copies of a gene to prevent his red
blood cells from becoming “sickled.” When the treated cells were
infused back into his body, they began to make normal blood
cells.
• Restoring sight
In December, the FDA approved the first gene therapy for an
inherited disease. The treatment, called Luxturna, aims to correct
a mutation responsible for a range of retinal diseases that make
people gradually go blind. In human tests, the treatment has
restored vision for more than two dozen patients who were losing
their sight.
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20. • Cancer treatment: The FDA calls the treatment, made by
Novartis, the “first gene therapy” in the U.S. The therapy is
designed to treat an often-lethal type of blood and bone marrow
cancer that affects children and young adults. Known as a CAR-
T therapy, the approach has shown remarkable results in
patients. Kymriah treats a bone marrow cancer that affects
children and young adults, and Yescarta treats a type of
lymphoma.
• Hemophilia : BioMarin is one company working on a gene
therapy that replaces the faulty gene involved in the most
common type of hemophilia, effectively curing the disorder. In
December, the company published early clinical trial
results showing that nine patients who received its therapy saw
substantial increases in the blood-clotting proteins absent in
hemophilia.
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21. • During 2016, Italian scientists at Milan’s San Raffaele Telethon
Institute for Gene Therapy reported that they had cured 18
children of a rare but terrible immune deficiency disease, ADA-
SCID. They removed the children’s bone marrow, added a gene
to make the ADA enzyme their bodies lack, and replaced
it. Technology Review explained how the treatment, now called
Strimvelis and owned by Glaxo, took 14 years to develop and
test. It was approved in Europe in May of this year.
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22. REFERENCES
• Biochemistry by U. Satyanarayana , U. Chakrapani 3rd edition
• http://www.rroij.com/open-access/gene-therapy-principles-and-
applications-in-dentistry-5-12.php?aid=34559
• https://journals.sagepub.com/doi/full/10.1177/01926233073099
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• www.slideshare.com
• https://academic.oup.com/hmg/article/5/Supplement_1/1397/6
61061
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