Gene therapy It means modification of the genetic material of living cells This applies to genetically determined diseases but may also expanded to diseases that occur later in life
Immunity enhancing (e.g., by adding a gene that suppresses tumor growth).
more technological barriers are encountered than foreseen and therefore, the clinical success up to now is limited.
Germ cell gene therapy
Germ cell gene therapy
Deposit corrective genes in the cell’s nucleus,
integrate genes into the chromosomes..
Somatic cell gene therapy The Concept Natural ability of viruses to enter cells through receptors genetically altered to carry normal human DNA.
How it is prepared!!
harmful viral genes are removed and replaced with the corrective gene. (Vector)
Viruses recognize and attach to receptors (a) and work their way through, into the cell (b). Once inside, the virus discharges its contents (c). Viral genes progress through the cell and into the nucleus (d).
How to select
Depending on the specific virus, these genes may or may not integrate into the host's chromosomes.
Each virus is particularly adapted to use one or a few specific receptors, which limits the range of cells each one can infect.
Cells may be modified ex vivo for subsequent administration to patients, or may be altered in vivo by gene therapy given directly to the subject.
A retroviral vector delivers a corrective low-density lipoprotein (LDL) receptor gene.
A piece of the patient's
liver is removed, and the cells
are treated with a retrovirus
carrying a good copy of the
Liver cells incorporating
the corrective gene are
implanted into the patient's
It is the future
Currently, within the context of clinical trials, (FDA) has not yet approved any human gene therapy product for sale.
gene therapy for single-gene diseases will be routine and successful within years.
Role in oncology
It has been proven that many cancers are caused by the mutation of certain genes or lack of gene function
The introduction of those genes into cancer cells where gene function is compromised, can work to restore gene function and stop tumor progression
May be in the future
Patients with cancer may receive combination chemotherapy together with gene therapy for six cycles of treatment
Gene Therapy: Simple in Theory but Difficult in Practice
Short-lived nature of gene therapy
Ethics : Baby designers
In a gene therapy trial for ornithine transcarboxylase deficiency (OTCD). An 18 years old boy died from multiple organ failures after starting the treatment. (? severe immune response to the adenovirus carrier)
A child successfully treated by gene therapy for X-linked severe combined immunodeficiency disease (X-SCID), known as "bubble baby syndrome." developed a leukemia-like condition.
Nonviral approach (2003)
involves the creation of an artificial lipid sphere with an aqueous core. This liposome, which carries the therapeutic DNA, is capable of passing the DNA through the target cell's membrane
potential for treating Parkinsonism
Where we stand!!
all of the current approaches to gene therapy seek to introduce the good gene into the so-called somatic cells of a child or an adult.
While somatic gene therapy is thought to be appropriate, germ line gene therapy is not allowed
More Effective Pharmaceuticals
Efforts will shift toward developing a new generation of therapeutics based on genes.
doctors will test individual genetic profiles against panels of drugs available for a specific condition and choose the treatment with the greatest potential benefit.
It is real
All will be manufactured by recombinant DNA technology just as human insulin and growth hormone are today
Types of Stem Cells Pluripotent Stem Cells: Can give rise to all different cell types in vitro . Multipotent Stem Cells: Can give rise to several cell types of a tissue or organ. Unipotent Stem Cells: consist of a single cell type only.
Sources of Stem Cells
Blastocyst embryos - pluripotent
Foetal tissues - pluripotent or multipotent
Umbilical cord blood - multipotent
Isolation of Embryonic Stem Cells Embryonic Stem cells Culture Inner Cell Mass BLASTOCYST 5-7 day old embryo
Differentiation of E.S.C. Using particular treatment regimes, embryonic stem cells can be made to differentiate into many types of cell. This is because they are pluripotent . Embryonic Stem Cells Liver Cells Muscle cells Skin cells