Therapeutic efficacy and safety of TRAIL-producing human adipose tissue–derived mesenchymal stem cells against experimental brainstem glioma
Advance Access publication November
Therapeutic efficacy and safety of TRAIL- producing human adipose tissue - derived mesenchymal stem cells against experimental brainstem glioma
Seung Ah Choi 0 1 2
Sung-Kyun Hwang 0 1 2
Kyu-Chang Wang 0 1 2
Byung-Kyu Cho 0 1 2
Ji Hoon Phi 0 1 2
Ji Yeoun Lee 0 1 2
Hee Won Jung 0 1 2
Do-Hun Lee 0 1 2
Seung-Ki Kim 0 1 2
K.-C.W. 0 1 2
B.-K.C. 0 1 2
J.H.P. 0 1 2
J.Y.L. 0 1 2
H.W.J. 0 1 2
D.-H.L. 0 1 2
S.-K.K.) 0 1 2
Seoul 0 1 2
South Korea 0 1 2
0 (S.-K.H.); Department of Neurosurgery, Seoul National University Hospital, College of Medicine (S.A.C.
1 J.H. P., J.Y.L., D.-H.L., S. -K.K.); Department of Neurosurgery, College of Medicine, Ewha Woman's University
2 Division of Pediatric Neurosurgery, Seoul National University Children's Hospital (S.A.C., K.-C.W., B.-K.C.
treated group, P < .0001), without any evidence of mesenchymal differentiation in vivo. Our study demonstrated the therapeutic efficacy and safety of nonvirally engineered hAT-MSCs against brainstem gliomas and showed the possibility of stem-cell - based targeted gene therapy for clinical application.
adipose tissue-derived mesenchymal stem cells; antitumor effect; brainstem glioma; tumor necrosis factor-related apoptosis-inducing ligand
Mesenchymal stem cells (MSCs) have an extensive
migratory capacity for gliomas, which is comparable
to that of neural stem cells. Among the various types
of MSCs, human adipose tissue-derived MSCs
(hATMSC) emerge as one of the most attractive vehicles for
gene therapy because of their high throughput, lack of
ethical concerns, and availability and ease of isolation.
We evaluated the therapeutic potential and safety of
genetically engineered hAT-MSCs encoding the tumor
necrosis factor-related apoptosis-inducing ligand
(TRAIL) against brainstem gliomas. Human AT-MSCs
were isolated from human fat tissue, characterized, and
transfected with TRAIL using nucleofector. The
therapeutic potential of TRAIL-producing hAT-MSCs
(hAT-MSC.TRAIL) was confirmed using in vitro and
in vivo studies. The final fate of injected hAT-MSCs
was traced in long-survival animals. The
characterization of hAT-MSCs revealed the expression of
MSCspecific cell-type markers and their differentiation
potential into mesenchymal lineage. Short-term
outcomes included a 56.3% reduction of tumor volume
(P < .001) with increased apoptosis (3.03-fold, P < .05)
in animals treated with hAT-MSC.TRAIL compared
with the control groups. Long-term outcomes included
a significant survival benefit in the
hAT-MSC.TRAILtreated group (26 days of median survival in the
control group vs 84 days in the
Dmost common form of brainstem gliomas,
iffuse intrinsic pontine gliomas, which are the
cannot be removed by surgery and remain
virtually inevitably lethal, with a mean survival period of
less than a year, despite some progress in adjuvant
radio-and chemotherapy. Currently, there is no effective
treatment modality for brainstem gliomas.1,2 These
disappointing results in the treatment of brainstem
gliomas have encouraged numerous experimental trials
in the search for a novel treatment, such as
stem-cell – based gene therapy.
Recently, gene therapy using neural stem cells (NSCs)
as the vehicle for therapeutic agents has emerged as a
promising treatment modality for malignant brain
tumors.3 – 8 Furthermore, studies have confirmed that
NSCs and various mesenchymal stem cells (MSCs),
such as bone marrow-derived MSCs (BM-MSCs),
adipose tissue-derived MSCs (AT-MSCs), and umbilical
cord blood-derived MSCs, can target brain tumors.9 – 18
Among the MSCs from various sources, AT-MSCs
exhibit clear advantages, which include the easy and
repeatable access to subcutaneous adipose tissue, the
simple isolation procedure, and the higher yield of
MSCs from adipose tissue compared with BM
(approximately 500-fold).19 Our previous study confirmed
that human AT-MSCs (hAT-MSCs) have an extensive
migratory capacity for experimental brainstem
gliomas, which is comparable to that of NSCs.20
To investigate the therapeutic potential of genetically
modified hAT-MSCs for brainstem gliomas, we used the
tumor necrosis factor-related apoptosis-inducing ligand
(TRAIL) gene. TRAIL, which is a member of the
tumor necrosis factor protein superfamily, is an
attractive genetic tool because it induces apoptosis selectively
in a variety of neoplastic cells without causing toxicity to
normal cells. TRAIL activates the p53-independent
extrinsic pathway by binding to the death receptors
DR4 (TRAIL-R1) and DR5 (TRAIL-R2/KILLER) at
the cell surface.21 – 24
In the present study, we demonstrate, for the first time,
that TRAIL-producing hAT-MSCs can induce potent
apoptotic activity in vitro and in vivo, resulting in
shortand long-term therapeutic efficacy. For safety reasons,
we conducted gene transduction using a nonviral vector
and monitored the long-term fate of injected
hAT-MSCs. The purpose of this study is to provide the
rationale for clinical application of the hAT-MSC– based
gene therapy against human brainstem gliomas.
Materials and Methods
Isolation and Expansion of hAT-MSCs and Cell Culture
Human AT-MSCs were isolated from human adipose
tissue. Adipose tissue samples were obtained from the
abdominal fat prepared for sellar floor reconstruction in
patients who had undergone transsphenoidal surgery at
the Seoul National University Children’s Hospital. All
eligible patients or their parents provided written informed
consent. Permission to isolate MSCs from the fat tissues
was given by the institutional review board of the Seoul
National University Hospital. Human AT-MSCs were
suspended in MSC expansion medium (Chemicon)
supplemented with 10% fetal bovine serum (FBS) and 1%
antibiotic– antimycotic solution (Invitrogen). F98 cells
that were originally obtained from American Type
Culture Collection (ATCC) were cultured in Dulbecco’s
modified Eagle’s medium (WelGene Biopharmaceuticals)
supplemented with 10% FBS and 1% antibiotic–
antimycotic solution. All cells were incubated at 378C in an
incubator in a 5% CO2/95% air atmosphere.
Fluorescence-activated Cell Sorting Analysis
Fluorescence-activated cell sorting (FACS) analyses were
performed on hAT-MSCs. Human AT-MSCs were
cultured in a control medium for 48 hours before analysis.
Cells were harvested in 0.25% trypsin/ EDTA and fixed
for 30 minutes in ice-cold 2% formaldehyde. The fixed
cells were washed in flow cytometry buffer (FCB; 2%
FBS, 0.2% Tween-20 in phosphate-buffered saline
[PBS]) and incubated for 30 minutes in FCB containing
fluorescein isothiocyanate-conjugated monoclonal
antibodies directed against cluster of differentiation
(CD) antigens (CDs 14, 34, and 90, BD Biosciences
Pharmingen; CD 105, Chemicon) or
phycoerythrinconjugated monoclonal antibodies directed against CD
antigens (CD 73, BD Biosciences Pharmingen; CD 45,
Chemicon). Flow cytometry was performed using a
FACscan argon laser cytometer (Becton Dickinson).
In vitro Adipogenic, Osteogenic, and Chondrogenic
Differentiation of hAT-MSCs
The potential of hAT-MSCs to differentiate into
adipogenic, osteogenic, and chondrogenic lineages was
assayed. Cells were seeded in culture plates at 2.5 ×
104 cells/cm2 in hMSC culture media until confluence.
Cells were then stimulated under appropriate inducible
conditions. Unstimulated cells and cells treated with
identical amounts of diluents were used as controls.
For adipogenic differentiation, cells were induced with
adipocyte induction media (Invitrogen) for 2 weeks with
a medium change three times a week. Cells were then
rinsed twice with PBS, fixed with 10% formalin for
10 minutes, washed with distilled water, rinsed in 60%
isopropanol, and covered with a 0.3% oil red O solution
(Sigma) for 10 minutes. Stained cells were briefly rinsed
in 60% isopropanol and thoroughly washed in distilled
water and left to dry at room temperature (RT).
For osteogenic differentiation, cells were stimulated
every 2 days in osteogenic induction media (Invitrogen).
After 3 weeks, cells were rinsed twice with PBS, fixed
with formalin for 10 minutes, and washed with distilled
water. To stain calcium deposits, cells were covered with
a 2% aqueous solution of alizarin red S (Sigma), pH 4.2,
for 3 minutes. Cultures were then washed thoroughly
with distilled water and left to dry at RT.
For chondrogenic differentiation, cells were
stimulated in chondrogenesis induction media (Invitrogen)
for 2 weeks. Cells were then rinsed twice with PBS and
fixed in 10% formalin for 10 minutes at RT. Alcian
Blue (Sigma) was used to stain chondrogenic pellets.
Excess dye was removed, and cells were visualized by
Engineering of TRAIL-producing hAT-MSCs
The pIRES2.GFP (5.3 kb) vector was purchased from
BD Biosciences Clontech and the TRAIL cDNA was
courtesy of Dr. Myong Hun Seong (Seoul National
University Hospital). TRAIL (850 bp) was inserted
into the XhoI/EcoRI (Invitrogen) cloning site of
pIRES2.GFP. Nucleofection was performed using the
Nucleofector machine (Amaxa Biosystems) according
to the manufacturer’s instructions with some
modifications.25 For each nucleofection assay, 5 × 105 cells
were resuspended in 100 mL of Nucleofector buffer
(Amaxa Biosystems) and nucleofected with 3 mg of
plasmid DNA. The U-23 protocol was tested on the
Nucleofector II device. Immediately after nucleofection
completion, cells were plated onto 6-well plates.
Culture medium was changed 5 hours after
nucleofection to remove dead cells. Transfection
efficiency in all samples was verified using a fluorescent
microscope and FACS analysis.
Reverse Transcription – Polymerase Chain Reaction
Total RNA was extracted using the TRIzol reagent
(Invitrogen) according to the manufacturer’s
instructions. Reverse transcription (RT) – PCR analysis
was conducted using the PrimeScript RT – PCR
kit (Takara). Thirty PCR cycles were performed for all
transcripts using the following primers: TRAIL,
CC-3′, reverse: 5′-GCCGAATTCTTAGCCAACTAAA
AAGGC-3′ (850 bp amplicon) and GAPDH, forward:
5′-CGTGGAAGGACTCATGAC-3′, reverse: 5′-CAA
TTCGTTGTCATACCAG-3′ (513 bp amplicon). The
PCR products were resolved on a 1% agarose gel
stained with ethidium bromide and were visualized
using a UV transilluminator.
In vitro Therapeutic Efficacy of hAT-MSC.TRAIL
To quantify TRAIL expression, hAT-MSC and
hATMSC.TRAIL cells (1 × 105/250 mL/well) were seeded
in 24-well plates and cultured for 24 hours. Culture
supernatants were harvested, and secreted TRAIL was
measured using the TRAIL Immunoassay Kit
(Invitrogen) according to the manufacturer’s protocol.
Plates were read at 450 hm using an absorbance plate
reader (Molecular Devices), and data were analyzed.
The therapeutic efficacy of hAT-MSC.TRAIL cells
was analyzed by coculture experiments using a cell
viability assay. F98 cells (4 × 103) were grown in 96-well
plates. Human AT-MSC or hAT-MSC.TRAIL cells
(1.2 × 104) were added to the tissue culture transwell
plate (0.4 mm pore size, Nunc International) on Day
1. Cells were incubated for 3 days and F98-cell viability
was measured using a colorimetric assay (Cell Counting
Kit-8, Dojindo Molecular Technologies). Experimental
values were expressed as the mean percentage of
control viability + SEM. All experiments were
conducted in triplicate.
In vivo Short-term Therapeutic Efficacy of hAT-MSC.TRAIL
All animal studies were carried out at the animal facility
of the Seoul National University Hospital in accordance
with national and institutional guidelines. Female
Fischer 344 rats (Central Lab Animal) weighing 150 –
200 g were used in this experiment. Rats (n ¼ 21) were
anesthetized with an intramuscular injection of a
solution of 20 mg/kg Zoletil (Virbac) and 10 mg/kg
xylazine (Bayer Korea). The posterior cranial region was
shaved and prepared in a sterile fashion. A midline
scalp incision of approximately 2 cm was made, and a
small burr hole was created using a 22-gauge needle.
To establish brainstem gliomas, F98 tumor cells were
stereotactically implanted into the right brainstem, as
described previously.20,26 The stereotactic coordinates
were 1.4 mm to the right of the sagittal suture and
1 mm anterior to the lambdoid suture. A 26-gauge
Hamilton needle was inserted at an angle of 58
anteflexed from vertical, to a depth of 7 mm from the dura
mater. F98 tumor cells (40 000 cells in 3 mL; n ¼ 21)
were then implanted via the needle at an injection rate
of 1 mL/min. Three days after tumor cell implantation,
the animals were randomized into 3 groups and
treated with intratumoral inoculations of PBS (12 mL;
n ¼ 7), hAT-MSC cells (160 000 cells; n ¼ 7), or
hAT-MSC.TRAIL cells (160 000 cells; n ¼ 7) in 12 mL
of PBS at the established tumor site, using the same
burr hole and stereotactic coordinates. Eighteen days
after tumor implantation, the animals were perfused
with 4% paraformaldehyde under deep anesthesia and
sacrificed. After fixation, the entire brain was
sequentially dehydrated in 10%, 20%, and 30% sucrose
solution, embedded in an optimum cutting temperature
compound (Tissue-Tek), and stored at 2808C. The
brains were then sectioned using a cryotome and
stained with hematoxylin and eosin (H&E).
The size of the tumor and the effect of therapeutic cells in
brainstem structures were assessed. Tumor volumes were
estimated using the formula for ellipsoid and expressed as
the mean + SEM, as described previously.20 The primary
antibodies used for immunofluorescence staining included
anti-Ki67 nuclear antigen (1:100; DAKO) for the detection
of proliferating cells and anticleaved caspase-3 (1:100;
Cell Signaling Technology) for the detection of apoptosis.
The secondary antibody used was the Alexa Fluor
633conjugated rabbit anti-mouse immunoglobulin-G (IgG)
(1:200; Invitrogen). Sections were counterstained with
4′,6-diamidino-2-phenylindole (DAPI), and negative
control slides were established by omitting the primary
antibody. The apoptotic and proliferating indices were
defined as the percentage of cells stained positively per
100 nuclei from 5 randomly selected high-power fields.
The sections were observed using a confocal microscope
In vivo Long-term Therapeutic Efficacy of hAT-MSC.TRAIL
F98 tumor cells were stereotactically implanted into
the right brainstem (n ¼ 27), as described previously.
After 3 days, rats were randomized into 3 groups (n ¼
9 per group) and treated with PBS, hAT-MSC, or
hAT-MSC.TRAIL. Discomfort or distress was assessed
by animal care personnel with no knowledge of the
protocol design. Survival was followed until the rats were
dead or for a maximum of 100 days, at which time
animals were sacrificed. All euthanized rats were verified
as bearing tumors by necropsy.
Two rats that survived for 100 days after tumor
injection were sacrificed, and their brains were
collected for confirmation of differentiation of injected
hAT-MSC.TRAIL. Neural and mesenchymal
differentiation were investigated and evaluated using primary
antibodies directed against Tuj1 (1:500; Chemicon) as
a neuronal marker, GFAP (1:500; Covance) as an
astrocyte marker, CNPase (1:200; Chemicon) as an
oligodendrocyte marker, adiponectin (1:200; ProSci) as
an adipose-tissue marker, bone sialoprotein (BSP,
1:500; Chemicon) as a bone marker, and aggrecan
(1:100; Abcam) as a cartilage marker. The secondary
antibody used was the Alexa Fluor 594-conjugated
goat anti-mouse IgG (1:200; Invitrogen). Sections were
mounted with antifading solution containing DAPI.
Sections were observed using a confocal microscope.
All values were calculated as means + SEM or were
expressed as a percentage of controls + SEM. The
GraphPad Prism software (GraphPad Software) was
used for all the analyses. Significant differences in the
assessment of cell viability, tumor volume, proliferation,
and apoptosis index were determined using the Kruskal –
Wallis test with post hoc analysis. The survival data are
presented as Kaplan – Meier plots and were analyzed
using a log-rank test. Significance was set at P , .05.
hAT-MSCs Could Be Isolated and Expanded
from Adipose Tissue
To characterize the hAT-MSC population, the isolated
cells were analyzed using flow cytometry analysis.
Cells were analyzed for the expression of cell membrane
protein markers: positive for CD73, CD90, and CD105,
which are generally considered as markers of MSCs, but
negative for the expression of hematopoietic markers
such as CD14, CD34, and CD45 (Fig. 1A).
Human AT-MSCs showed a fibroblast-like
morphology and were plastic adherent under standard
culture conditions (Fig. 1B).
The differentiation potential for mesenchymal
lineage was assessed by oil red O, alizarin red S, and
alcian blue staining. Human AT-MSCs exhibited a
characteristic of differentiation morphology in induction
medium (+) but not control medium (2) (Fig. 1B). Two
weeks after adipogenic induction, morphology of lipid
droplets was observed and stained by oil red O. Under
osteogenic culture conditions after 3 weeks, calcium
deposits were detected by alizarin red S staining.
Chondrogenic differentiation was revealed by alcian
blue staining after 2 weeks of chondrocyte induction.
hAT-MSCs Were Engineered to Produce TRAIL
After transfection of hAT-MSCs with the TRAIL
construct (or vector alone as a control) and subsequent
antibiotic selection, G418-resistant cells were expanded
in T75 flasks. RT – PCR produced the expected 850 bp
band of the inserted TRAIL cDNA in
hATMSC.TRAIL cells, but not in hAT-MSC cells (Fig. 2A).
These cells were positive for green fluorescent protein
(GFP) expression, as assessed by fluorescence microscopy
(Fig. 2B). Of the hAT-MSC-TRAIL cells 62.6% showed
GFP positivity on FACS analysis 3 and 7 days after
transfection (Fig. 2C).
hAT-MSC.TRAIL Retained Therapeutic Efficacy
An enzyme-linked immunosorbent assay (ELISA) was
performed to quantify the secreted TRAIL protein in
hAT-MSC.TRAIL culture media. Human AT-MSC.
TRAIL supernatant contained increased levels of
TRAIL, in a cell number – dependent fashion.
Approximately 5 × 103 hAT-MSC.TRAIL cells secreted
1 hg/mL of TRAIL protein in 24 hours (Fig. 3A).
To confirm the cytotoxic effect of hAT-MSC.TRAIL,
cell viability was observed in a coculture system. The
number of F98 cells cultured with hAT-MSC.TRAIL
cells decreased by 59.5% compared with control F98
cells alone (P , .05; Fig. 3B).
hAT-MSC.TRAIL Led to Tumor Volume Reduction
and Induced Apoptosis
In vivo studies showed that the majority of intracranially
injected hAT-MSC.TRAIL cells localized to the
tumor bed and to the tumor – normal parenchyma
interface. Histological analysis showed a 56.3%
reduction of tumor volume in the
hAT-MSC-TRAILtreated rats compared with PBS-treated control
animals and hAT-MSC-treated rats (PBS vs hAT-MSC
vs hAT-MCS.TRAIL, 117.1 + 21.9vs 105.9 + 35.0 vs
51.1 + 29.7 mm3; P , .001; Fig. 4A and B). We did
not detect any abnormalities in the parenchyma
surrounding the tumor in treated rats. We assessed the
biological action of hAT-MSC.TRAIL on the brainstem
gliomas. Immunofluorescence analysis revealed a
significant increase (3.01-fold) in the number of apoptotic cells
in animals treated with hAT-MSC.TRAIL compared
with control groups (P , .05; Fig. 4C and D). In
contrast, the proliferative indices revealed no significant
differences among the groups (Fig. 4C and D).
hAT-MSC.TRAIL Conferred a Survival Gain Without
Our data showed that hAT-MSC.TRAIL – treated rats
survived significantly longer (median survival, 84 days)
compared with control animals treated with PBS
(median survival, 26 days) or hAT-MSC (median
survival, 29 days; P , .0001; Fig. 5A). Tissues from
TRAIL-treated long-survival rats exhibited expression
of the neural differentiation markers Tuj1, GFAP, and
CNPase but did not express the mesenchymal
differentiation markers adiponectin, BSP, and aggrecan
Several essential premises should be satisfied for the clinical
application of stem-cell–based gene therapy to brain
malignancy. First, the supply of stem cells should be
secure and stable. Second, the therapeutic gene transfection
method should be safe and effective. Third,
stem-cell-related complications should be absent or
The prototype cell used in stem-cell – based gene
therapy for brain tumors is the NSC.3 – 8 However, the
practical application of NSCs is limited by ethical and
logistic problems related to their isolation and to their
potential immunogenicity because of a requirement for
allogenic transplantation.9,10,12,15 Increasing
recognition is being given to the plasticity of stromal cells
within BM (termed MSCs) as an alternative method.
These cells can differentiate into multiple mesenchymal
lineages such as osteocyte, adipocyte, and
chondrocyte.18,27 Previous studies have confirmed that
BM-MSCs have all the properties of NSCs, such as an
extensive migratory capacity and tropism for
gliomas.20 Therefore, they have been investigated as
vehicles for gene therapy targeting malignant
glioma.14,15 However, invasive isolation procedures,
low yield, and potential malignant transformation for
BM-MSCs represent an obstacle to their use in cellular
therapy applications.28 Recently, adult adipose tissue
has emerged an alternative method for autologous
adult NSC therapy.29 Adipose tissue contains a
specialized class (the stromal vascular fraction), which is
thought to harbor stem cells that display an extensive
proliferative capacity and multilineage potential,
provide a rich source of pluripotent stromal stem cells,
and have the capacity for autologous transplantation.
Compared with BM-derived stem cells, adipose
tissuederived stem cells have an equal potential regarding
morphology, immune phenotype, success rate in
isolating MSCs, colony frequency, and differentiation
into cells and tissues of mesodermal origin. The easy
and repeatable access to subcutaneous adipose tissue
and simple, uncomplicated enzyme-based isolation
procedure represent a clear advantage.18,19,29,30 Therefore,
we selected the adipose tissue as a cellular source of
MSCs among the various possible sources. We
successfully isolated and maintained hAT-MSCs from human
adipose tissue. These hAT-MSCs showed a
fibroblastlike morphology, expressed typical surface markers,
and had differentiation potential to mesenchymal
lineage.31 – 33 As the case of the adipose tissue-derived
stem-cell therapy for cancer, this study is the first trial
for brain malignancy after colon cancer.29
Viral-based techniques are the most efficient
therapeutic gene transfection systems used to deliver DNA
into stem cells, as they yield high gene transduction
and transgenic expression in many cellular models.
However, viral methods are practically complex, labor
intensive, and involve safety risks complicated by
immune response, intracellular trafficking, potential
mutations, and genetic alterations caused by integration.
Therefore, we chose a nonviral transfection method –
the nucleofection technique. Nucleofection is a recent
electroporation-based technique that combines electrical
parameters and a cell-type solution to drive plasmid
DNA, oligonucleotides, or siRNA directly into the cell
nucleus. This technology has been successfully used to
transfect several primary cell types, including mouse T
cells, neurons, and keratinocytes, as well as human and
mouse stem cells of diverse origins.34 This method
does not alter the differentiation ability of these clones,
as they underwent differentiation without altering the
differentiation potential and loss of transgene
expression.35,36 We successfully transfected the
recombinant TRAIL gene using the nucleofection technique,
with a transfection efficiency of 62.6% in living cells.
Our data clearly demonstrated that nucleofection can
be used to generate efficient and stable transgene
expression in hAT-MSCs, without altering stem cell
features and functions.
In this study, the in vivo hAT-MSC.TRAIL
experimental design led to a significant short-term (56.3%
reduction of tumor volume; P , .001) and long-term
(.3-fold survival gain; P , .0001) therapeutic efficacy
in the hAT-MSC.TRAIL – treated group. Although the
therapeutic efficiency of stem cell-based gene therapy
has been published, its safety has been addressed
poorly.37,38 In the present study, the histological analysis
of the short-term therapeutic efficacy of
hATMSC.TRAIL showed no normal parenchymal injury.
Furthermore, histological analysis of long-term survival
animals showed no mesenchymal differentiation. These
results provide evidence of the safety of this approach
in clinical applications.
In spite of the short and long-term therapeutic
efficacy observed, complete remission was not
accomplished. Repeated injection of therapeutic MSCs or
using the secretable TRAIL may improve the therapeutic
efficiency. However, an omnipotent therapeutic gene is
still lacking. Although such a gene remains unidentified,
a combination therapy using traditional standard
treatments remains valid.
In conclusion, we successfully isolated hAT-MSCs
from human adipose tissue and modified cells with an
effective recombinant gene using a nonviral method.
Genetically modified hAT-MSCs exhibited short- and
long-term therapeutic effects without any complications
related to stem cell therapy. Our results bring stem-cell –
based gene therapy for brain malignancy one step closer
to clinical application.
Conflict of interest statement. None declared.
This study was supported by a grant from the
National R&D Program for Cancer Control, Ministry
of Health & Welfare, Republic of Korea (0820310),
and by grant from the Seoul National University
Hospital Research Fund (03-2008-009).
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