Biomedical Engineering Reference
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resulting in 1-2% expression of FVIII in six patients
[329]
. In other clinical trails,
FVIII cDNA was given using retroviral/adenovirus vectors by peripheral intravenous
infusion. The results showed an expression of around 1% FVIII in the patients
[330]
.
A phase I clinical trial was initiated to test the safety of an adenoviral vector encoding
human FVIII for the treatment of hemophilia A. The subjects under investigation expe-
rienced inflammation, fever, and other complaints upon viral administration
[331]
. In
a clinical trial for hemophilia B, an adeno-associated virus containing FIX cDNA was
delivered to the liver and muscles, resulting in 3-12% (liver) and 3-4% (muscles) of
FIX expression in two patients
[332]
.
6.9 Conclusion
Gene therapy has been proven to be an incredibly powerful tool for the prevention
and cure of diseases as it aims to treat the cause rather than the symptoms of diseases.
Although the fundamental principle underlining gene therapy is theoretically straight-
forward, for want of an ideal vector it is difficult to achieve in practice satisfactorily.
There are a number of human diseases, both genetic and acquired, for which gene-
based therapeutic approaches are gaining appraisals for genetic and acquired diseases.
Moreover, development of DNA vaccines represents a new approach for immuniza-
tion and immunotherapy, in which DNA containing the genes that encode proteins of
the pathogen are to be delivered.
Gene therapy has reached a stage where a number of clinical trials have been car-
ried out on patients with genetic and acquired diseases. Since 1990, when the first
successful gene therapy trial was undertaken to treat a girl suffering from SCID,
around 1579 clinical trials have been completed, are ongoing, or have been approved
using various approaches. These clinical trials utilized both viral and nonviral vectors,
but as a number of disadvantages are associated with viral vectors, nonviral vectors
with improved safe and efficient transfection are the major focus area of current gene
therapy research. The majority of human gene therapy clinical trials conducted to date
are aimed at treating cancer. Two gene products, namely, Gendicine and Endostar,
have been approved by the State Food and Drug Administration of China for market.
A gene medicine is composed of an expression system with a gene of interest and
a gene delivery system. The majority of researches have focused on the design of a
gene delivery system that can offer high transfection efficiency with minimal toxicity.
Continued research in the area of gene therapy can develop a “gene as a substitute for
a drug” in the near future.
Acknowledgment
The authors acknowledge the financial assistance of the University Grants
Commission and TIFAC CORE in NDDS, Government of India, New Delhi, for pro-
viding research facilities to the team.
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