Current Gene Therapy, Volume 5, No. 2, 2005
Contents
What they are, How they Work and Why they do
What they do? The Story of SV40-derived Gene Therapy Vectors and What They Have
to Offer Pp.151-165
David
S. Strayer, Pierre Cordelier, Rumi Kondo, Bianling Liu, Alexey A.
Matskevich,Hayley J. McKee, Carmen N. Nichols, Christine B. Mitchell, Dawn A.
Geverd, Martyn K. White and Marlene S. Strayer
Gene Therapy for Bone Regeneration Pp.167-179
Jeffrey
Luo, Michael H. Sun, Quan Kang, Ying Peng, Wei Jiang, Hue H. Luu, Qing Luo, Jae
Yoon Park, Yien Li, Rex C. Haydon and Tong-Chuan He
Non-Viral Gene Delivery to the Lungs Pp.181-194
Berma
M. Kinsey, Charles L. Densmore and Frank M. Orson
Gene Therapy in In Vivo Isolated
Perfusion Models Pp.195-202
Boudewijn
van Etten, Alexander M.M. Eggermont, Sandra T. van Tiel, G. Ambagtsheer,
Johannes H.W. de Wilt and Timo L.M. ten Hagen
Adenoviral Gene Delivery for HIV-1
Vaccination Pp.203-212
T.
Vanniasinkam and H.C.J. Ertl
Cancer Gene Therapy Utilizing Interleukin-13
Receptor a2 Chain Pp.213-223
Koji
Kawakami
DNA Repair Proteins as Molecular Therapeutics
for Oxidative and Alkylating Lung Injury Pp.225-236
Min
Wu
Adenovirus-mediated Transgene-engineered
Dendritic Cell Vaccine of Cancer Pp.237-247
Qiaohua
Wu, Dajing Xia, Svein Carlsen and Jim Xiang
Approaches for the Cure of Type 1 Diabetes by
Cellular and Gene Therapy
Pp.249-262
H.-S.
Jun and J.-W. Yoon
Abstracts
[Back to top] What they are, How they Work and Why they do What they
do? The Story of SV40-derived Gene Therapy Vectors and What They Have to Offer
David
S. Strayer, Pierre Cordelier, Rumi Kondo, Bianling Liu, Alexey A.
Matskevich,Hayley J. McKee, Carmen N. Nichols, Christine B. Mitchell, Dawn A.
Geverd, Martyn K. White and Marlene S. Strayer
The natural
function of viruses is to deliver their genetic material to cells. Among the
most effective of viruses in doing that is Simian Virus-40 (SV40). The
properties that make SV40 a successful virus make it an attractive candidate for
use as a gene delivery vehicle: high titer replication, infectivity for almost
all nucleated cell types whether the cells are dividing or resting, potential
for integration into cellular DNA, a peculiar pathway for entering cells that
bypasses the cells’ antigen processing apparatus, very high stability, and the
apparent ability to activate expression of its own capsid genes in trans.
Exploiting these and other characteristics of wild type (wt) SV40, increasing
numbers of laboratories are studying recombinant (r) SV40-derived vectors.
Among the uses to which these vectors have been applied are: delivering therapy
to inhibit HIV, hepatitis C virus (HCV) and other viruses; correction of
inherited hepatic and other protein deficiencies; immunizing against lentiviral
and other antigens; treatment of inherited and acquired diseases of the central
nervous system; protecting the lung and other organs from free radical-induced
injury; and many others. The effectiveness of these vectors is a reflection of
the adaptive evolution that produced their parent virus, wt SV40. This article
explores how and why these vectors work, their strengths and their limitations,
and provides a functional model for their exploitation for experimental and
clinical applications.
[Back to top] Gene Therapy for Bone Regeneration
Jeffrey
Luo, Michael H. Sun, Quan Kang, Ying Peng, Wei Jiang, Hue H. Luu, Qing Luo, Jae
Yoon Park, Yien Li, Rex C. Haydon and Tong-Chuan He
Efficacious bone
regeneration could revolutionize the clinical management of many bone and
musculoskeletal disorders. Bone has the unique ability to regenerate and
continuously remodel itself throughout life. However, clinical situations arise
when bone is unable to heal itself, as with segmental bone loss, fracture
non-union, and failed spinal fusion. This leads to significant morbidity and
mortality. Current attempts at improved bone healing have been met with limited
success, fueling the development of improved techniques. Gene therapy in many
ways represents an ideal approach for augmenting bone regeneration. Gene
therapy allows specific gene products to be delivered to a precise anatomic
location. In addition, the level of transgene expression as well as the
duration of expression can be regulated with current techniques. For bone
regeneration, the gene of interest should be delivered to the fracture site,
expressed at appropriate levels, and then deactivated once the fracture has
healed. Delivery of biological factors, mostly bone morphogenetic proteins
(BMPs), has yielded promising results both in animal and clinical studies.
There has also been tremendous work on discovering new growth factors and
exploring previously defined ones. Finally, significant advances are being made
in the delivery systems of the genes, ranging from viral and non-viral vectors
to tissue engineering scaffolds. Despite some public hesitation to gene
therapy, its use has great potential to expand our ability to treat a variety of
human bone and musculoskeletal disorders. It is conceivable that in the near
future gene therapy can be utilized to induce bone formation in virtually any
region of the body in a minimally invasive manner. As bone biology and gene therapy
research progresses, the goal of successful human gene transfer for
augmentation of bone regeneration draws nearer.
[Back to top] Non-Viral Gene Delivery to the Lungs
Berma
M. Kinsey, Charles L. Densmore and Frank M. Orson
The lung
represents an important target for gene therapy: for correction of genetic
abnormalities such as cystic fibrosis, for lung cancer therapy, and for
vaccination. Genes in the form of expression plasmids can be delivered both by
the intravenous route and via the airways. So-called “naked” DNA can be
delivered by both of these methods, but gene expression is low. Successful
delivery is usually accomplished by complexing the DNA with cationic lipids or
with polycations. This review will discuss the efficacy of delivery for
particular purposes by various methods and complexing agents, as well as issues
of biodistribution, inflammatory reactions, and improvements in formulations.
Non-viral gene delivery to the lung has a long history of development, and it
is now poised to represent a significant addition to the medical arsenal.
[Back to top] Gene Therapy in In Vivo Isolated
Perfusion Models
Boudewijn
van Etten, Alexander M.M. Eggermont, Sandra T. van Tiel, G. Ambagtsheer,
Johannes H.W. de Wilt and Timo L.M. ten Hagen
Locoregional
administration of a genetic construct by means of in vivo, in situ
isolated perfusion (IP) of a target organ or extremity is a method that may
increase in vivo efficacy. Vascular isolation and perfusion minimizes
systemic exposure and thereby reduces unwanted side effects. Isolated hepatic
perfusion (IHP) is the most extensively studied IP model, especially in gene
therapy protocols for inborn errors of metabolism. To achieve stable
transduction most frequently retroviruses are used in IHP. IHP is combined with
hepatectomy or vascular ligation of liver lobes to induce liver regeneration
increasing transduction efficacy. When adenoviruses are used in IHP high
transduction percentages of hepatocytes can be achieved without significant
toxicity. In tumor models adenoviral IHP has been performed, but has not been
very successful up till now.
Isolated limb
perfusion (ILP) is a promising treatment modality in pre-clinical cancer gene
therapy studies. After ILP a homogeneous distribution of transduced cells was
demonstrated especially at the viable rim of the tumor and around tumor associated
vessels. Moreover complete tumor responses have been observed. Isolated
pulmonary perfusion (IPP) results in selective expression in the perfused lung
and the duration of expression is longer than after systemic administration. In
rats a significant decrease of tumor nodules upon IPP can be achieved.
Furthermore other less studied perfusion models are discussed: isolated kidney
perfusion (IKP), isolated spleen perfusion (ISP) and isolated cardiac perfusion
(ICP).
IP is a
methodology that delivers vectors highly selectively, with a long exposure time
and high concentrations at the target side. This results in higher transduction
rates and thereby may improve therapeutic effects.
[Back to
top] Adenoviral Gene Delivery for HIV-1
Vaccination
T.
Vanniasinkam and H.C.J. Ertl
The AIDS epidemic
continues to spread throughout nations of Africa and Asia and is by now
threatening to undermine the already frail infrastructure of developing
countries in Sub-Saharan Africa that are hit the hardest. The only option to
stem this epidemic is through inexpensive and efficacious vaccines that prevent
or at least blunt HIV-1 infections. Despite decades of pre-clinical and
clinical research such vaccines remain elusive. Most anti-viral vaccines act by
inducing protective levels of virus-neutralizing antibodies. The envelope
protein of HIV-1, the sole target of neutralizing antibodies, is constantly
changing due to mutations, B cell epitopes are masked by heavy glycosylation
and the protein’s structural unfolding upon binding to its CD4 receptor and
chemokine co-receptors. Efforts to induce broadly crossreactive virus-neutralizing
antibodies able to induce sterilizing or near sterilizing immunity to HIV-1
have thus failed. Studies have indicated that cell-mediated immune responses
and in particular CD8+ T cell responses to internal viral proteins may
control HIV-1 infections without necessarily preventing them. Adenoviral
vectors expressing antigens of HIV-1 are eminently suited to stimulate potent
CD8+ T cell responses against transgene products, such as antigens
of HIV-1. They performed well in pre-clinical studies in rodents and nonhuman
primates and are currently in human clinical trials. This review summarizes the
published literature on adenoviral vectors as vaccine carriers for HIV-1 and
discusses advantages and disadvantages of this vaccine modality.
[Back to top] Cancer Gene Therapy Utilizing Interleukin-13
Receptor a2 Chain
Koji
Kawakami
Cancer cells are
known to express cell surface molecules such as specific antigens or cytokine
receptors, e.g., EGFR, Fas/CD95, gp100, HER-2/neu, IL-13Ra2, and MAGE. Among them, interleukin-13
receptor (IL-13R) a2 chain is expressed on
certain types of cancer cells including glioblastoma, AIDS Kaposi’s sarcoma,
and head and neck cancer. This protein is one of the receptor components for
IL-13, a Th2 cell-derived pleiotropic immune regulatory cytokine. IL- 13Ra2 chain on these cancer cells can be targeted
with a receptor-directed cytotoxin termed IL13-PE to induce specific cancer
cell killing, however, this molecule does not mediate cytotoxicity to cells that
do not express or express low levels of IL-13Ra2.
In order to achieve a broad therapeutic window for IL13-PE, plasmid-mediated
gene transfer of IL-13Ra2 in cancer
cells was employed in vitro and in vivo. Cancer cells transfected
with IL-13Ra2 demonstrated increased binding to IL-13 and
sensitivity to IL13-PE in vitro. In vivo intratumoral gene
transfer of IL-13Ra2 profoundly enhanced
the antitumor activity of IL13-PE, providing complete elimination of
established tumor in some xenografts. In this review article, current findings
from IL-13Ra2 gene transfer in a variety of human cancer
models in nude mice are summarized. In addition, safety issues and possible
future directions utilizing this therapeutic approach are discussed.
[Back to top] DNA Repair Proteins as Molecular Therapeutics
for Oxidative and Alkylating Lung Injury
Min
Wu
Endogenous and
environmental oxidation is increasingly becoming an important factor associated
with numerous disorders in both children and adults. The lung is particularly
prone to oxidation, as the gas exchange organ is continuously exposed to a
great deal of airborne oxidants. Lung oxidation-induced toxicity is a critical
clinical problem that is currently lacking cure. For example, treatment for
acute respiratory distress syndrome (ARDS), a common type of acute diffuse lung
injury, is strictly supportive. Alkylating chemotherapeutics and many methyl
chemicals can cause acute or chronic lung injury, which is also difficult to
treat. Many new approaches are being tried to improve the treatment of lung oxidation
and alkylation; one of these is the use of DNA repair proteins, such as base
excision repair proteins that are largely involved in repairing DNA damage
caused by oxidation and alkylation. Recent advances have revealed their promising
potential for treating oxidation toxicity. Here we discuss discoveries that
have led to this possibility, including pioneering research into the cellular
signaling transduction and molecular mechanisms of DNA repair proteins. In
conclusion, when combined with other therapeutic measures such as anti-oxidant
chemicals and enzymes, DNA repair proteins may have great potential for
treating acute and chronic lung toxicity induced by oxidation and alkylation.
[Back to top] Adenovirus-mediated Transgene-engineered
Dendritic Cell Vaccine of Cancer
Qiaohua
Wu, Dajing Xia, Svein Carlsen and Jim Xiang
Dendritic cells
(DCs) are the most effective antigen presenting cells (APCs) to elicit both
primary and secondary T-cell response that is critical for antitumor immunity
and elimination of intracellular pathogens. Therefore, DCs pulsed ex vivo
with antigens have the potential used as cell-based vaccines against tumors.
Viral vectors derived from adenoviruses have been extensively used to pulse DCs
ex vivo by delivering genes encoding immunomodulatory molecules and tumor
antigens to DCs since these vectors are relatively safe, effective in inducing
the maturation of DCs, and can accommodate large expression cassettes encoding
antigens. One of the hurdles for gene delivery to DCs by adenovirus (Ad)
vectors, however, is low transfection efficiency of DCs due to the paucity of
Ad receptor on DCs. To overcome this obstacle, targeted Ad vectors have been
made by modifying viral capsid proteins. These targeted Ad vectors not only enhance
the gene delivery to DCs, but also allow in vivo gene delivery to DCs,
thus avoiding ex vivo manipulation of DCs.
[Back to top] Approaches for the Cure of Type 1 Diabetes by
Cellular and Gene Therapy
H.-S.
Jun and J.-W. Yoon
Type 1 diabetes
results from insulin deficiency caused by autoimmune destruction of
insulin-producing pancreatic b cells.
Islet transplantation, b cell
regeneration, and insulin gene therapy have been explored in an attempt to cure
type 1 diabetes. Major progress on islet transplantation includes substantial
improvements in islet isolation technology to obtain viable and functionally
intact islets and less toxic immunosuppressive drug regimes to prevent islet
graft failure. However, the availability of human islets from cadaveric
pancreata is limited. Regeneration of pancreatic b cells
from embryonic or adult stem cells may overcome the limited source of islets
and transplant rejection if b cells are
regenerated from endogenous stem cells. However, it is difficult to overcome
the persisting hostile b cell-specific
autoimmune response that may destroy the regenerated b cells. Insulin gene therapy might overcome
the weakness of islet transplantation and b cell
regeneration with respect to their vulnerability to autoimmune attack. This
method replaces the function of b cells by
introducing various components of the insulin synthetic and secretory machinery
into non- b cells, which are not targets of b cell-specific autoimmune responses. However,
there is no regulatory system that results in the expression and release of
insulin in response to glucose with satisfactory kinetics. Although there is no
perfect solution for the cure of type 1 diabetes at the present time, research
on a variety of potential approaches will offer the best choices for the cure
of human type 1 diabetes.