Local effects of dexamethasone on immune reaction in neural transplantation.
ABSTRACT This study was performed to see whether local injection of dexamethasone may protect the neural grafts from immunological rejection and increase the successive rate of graft. Rats with unilateral 6-hydroxydopamine lesions of the mesostriatal dopamine pathway received fetal ventral mesencephalic (FVM) cells and dexamethasone in two regions of the striatum and showed significant (P<0.001) reduction in rotational asymmetry as compared to the non-immunosuppressed group. A significantly greater number of total TH-ir cells (P<0.001) and fewer number of total GFAP -ir cells (P<0.001) and inflammatory cells were observed in the striatum of animals in immunosuppressed group than those in non-immunosuppressed group. This results indicated that local injection of dexamethasone could not only reduce the immune rejection and increase the survival grafted cell but also avoid the side effects brought by long systemic administer of immunosuppressant.
- Brain Research 12/1988; 472(3):287-324. · 2.88 Impact Factor
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ABSTRACT: An important issue in clinical neural grafting is whether a second instriatial allograft can survive well in a patient who has received an allograft before. In this study, the survival, immunogenicity and function of intrastriatal grafts of allogeneic or syngeneic embryonic dopamine-rich tissue in rats which had previously received either an intrastriatal allo- or syn-graft or sham injections were examined. The first graft tissue was taken from inbred Lewis or Sprague-Dawley rat embryos and grafted into an intact striatum of adult Sprague-Dawley rats subjected to a unilateral 6-hydroxydopamine lesion on the contralateral side. Eight weeks after the first transplantation, either allogeneic or syngeneic tissue was grafted as dissociated tissue into the dopamine depleted striatum. The function of the second grafts was assessed by rotational asymmetry at two different time points, i.e. eight and 14 weeks after the second transplantation. There were significant reductions of rotational asymmetry in all groups over time, but no significant difference between groups. Tyrosine hydroxylase immunocytochemistry was used to assess dopamine cell survival and graft size. Statistical analysis revealed no significant differnce in the mean number of tyrosine hydroxylase immunoreactive cells or the mean volume of the second grafts placed on the right side (lesioned side) between groups. Monoclonal antibodies were used to evaluate cellular immune reactions and the major histocompatibility complex class I and class II expression in and around grafts. No major histocompatibility complex class I expression was seen in any of the graft combinations. The expression of the major histocompatibility complex class II antigens was generally higher in patches in and around the second allograft of rats which had previously received an allograft than that in and around any other type of grafts. However, the expression of the major histocompatibility complex class II antigens was low throughout the grafts and did not appear as marked perivascular infiltrates. All the major histocompatibility complex class II positive cells displayed a microglia-like morphology, supported by the parallel microglia and macrophage-specific OX-42 immunostaining. The results show that there is no marked on-going immune reactions in or around the implantation site in any group fourteen weeks after a second transplantation. It may be concluded, therefore, that sequential allografting, using stereotaxic implantation of dissociated embryonic neural tissue into the striatal parenchyma, is possible to perform without a major risk of graft rejection, provided that an atraumatic technique is used.Neuroscience 12/1993; 57(2):261-74. · 3.12 Impact Factor
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ABSTRACT: Six patients with Parkinson's disease were followed for 10 to 72 months after human embryonic mesencephalic tissue from four to seven donors was grafted unilaterally into the putamen (4 patients) or putamen plus caudate (2 patients). After 8 to 12 months, positron emission tomography showed a 68% increase of 6-L-[18F]-fluorodopa uptake in the grafted putamen, no change in the grafted caudate, and minor decreases in nongrafted striatal regions. There was therapeutically valuable improvement in 4 patients, but only modest changes in the other 2, both of whom developed atypical features. Patient 4 was without L-dopa from 32 months and had normal fluorodopa uptake in the grafted putamen at 72 months. Overall, the L-dopa dose was reduced by a mean of 10 and 20%, "off" time was reduced by 34 and 44%, and the "off" phase Unified Parkinson's Disease Rating Scale motor score by 18 and 26%, and the duration of the response to a single L-dopa dose increased by 45 and 58% during the first and second years after surgery, respectively. Rigidity and hypokinesia improved bilaterally, but mainly contralateral to the implant. No consistent changes in dyskinesias were observed. We conclude that transplantation of embryonic mesencephalic tissue leads to highly reproducible survival of dopaminergic neurons, inducing clinically valuable improvements in most recipients.Annals of Neurology 08/1997; 42(1):95-107. · 11.19 Impact Factor
Local effects of dexamethasone on immune reaction in neural transplantation
Yin Feng⁎, Tian Zengmin, Liu Shuang, Zhao Quanjun, Wang Yaming, Hao qiuxing
Institute of Neurosurgery, General Hospital of Navy, Beijing, China
Received 13 May 2007; accepted 22 May 2007
This study was performed to see whether local injection of dexamethasone may protect the neural grafts from immunological rejection and
increase the successive rate of graft. Rats with unilateral 6-hydroxydopamine lesions of the mesostriatal dopamine pathway received fetal ventral
mesencephalic (FVM) cells and dexamethasone in two regions of the striatum and showed significant (Pb0.001) reduction in rotational
asymmetry as compared to the non-immunosuppressed group. A significantly greater number of total TH-ir cells (Pb0.001) and fewer number of
total GFAP -ir cells (Pb0.001) and inflammatory cells were observed in the striatum of animals in immunosuppressed group than those in non-
immunosuppressed group. This results indicated that local injection of dexamethasone could not only reduce the immune rejection and increase
the survival grafted cell but also avoid the side effects brought by long systemic administer of immunosuppressant.
© 2007 Published by Elsevier B.V.
Keywords: Neural transplantation; Dexamethasone; Immunosuppressant; Parkinson disease
There has been considerable interest over the recent years in
the use of fetal neural tissue grafts to treat traumatic and
neuronal loss was thought irreparable, neural transplantation
reached a point where significant recovery of function was
reported, both in animal models and in clinical studies, especially
in the treatment of Parkinson disease. However, there have been
controversies over the use of immunosuppressant in the study of
brain grafting as well as in clinical transplantation of liver or
kidney [1,2]. Recent evidence has suggested that the CNS is only
a selective immunological privileged site. It has complicated
mechanism of immune . Some research groups used
immunosuppressive agent, such as Cyclosporine A (CyA), both
in animal models and in clinical studies. The results showed that
these agents could greatly improve the survival of embryonic
problems accompanying the use of immunosuppressant, such as
the side effects and the higher price, which hamper their use for
neural transplantation. According the characteristic of neural
transplantation, we suggest that local injection of dexamethasone
may protect the neural grafts from immunological rejection and
fetal ventral mesencephalic (FVM) with dexamethasone into
Sprague–Dawley (SD) rat of Parkinson model. And after the
2. Materials and methods
2.1. Experimental design
Thirty female SD rats (200–225 g, from the Experimental Laboratory of
Beijing University) were randomly divided into three equal groups with ten
animalsin each. The first group(A)received4 μl 0.9% NaClsolution.The second
group (B) was transplanted with grafts of 4×106/2 μl FVM cells and 2 μl 0.9%
NaCl solution in two regions of the striatum. The final group (C) received 4×106/
2 μl FVM cells and 2 μl dexamethasone in two regions of the striatum.
2.2. Animal model and 6-OHDA lesions
Rats received unilateral 6-OHDA lesions of the right median forebrain
bundle (MFB) and ventral tegmental area (VTA) under pentobarbital
Available online at www.sciencedirect.com
Transplant Immunology 18 (2007) 126–129
⁎Corresponding author. Institute of Neurosurgery, General Hospital of Navy,
Beijing, 100037, China. Tel.: +86 10 6695 1129, +86 10 6695 8005; fax: +86 10
E-mail address: email@example.com (Y. Feng).
0966-3274/$ - see front matter © 2007 Published by Elsevier B.V.
anaesthesia. Following 2 weeks recovery period, animals were challenged with
Apomorpine (APO, Sigma, and 0.5 mg/kg) and their rotational scores collected
over a 90-min period. Only animals exhibiting a mean contralateral rotational
score of 7 or fuller body turns/min were included in the studies .
2.3. Cell suspension and culture preparation
This procedure was done according to the method described previously by
Nikkhah and colleagues . Briefly, fetuses (embryonic day 13) were removed
from pregnant SD rats anaesthetized with 2% pentobarbital (50 mg/kg). The
ventral mesencephalons were dissected in DMEM (Gibco) and tissues were
incubated in 0.1% trypin/0.05% DNAse/DMEM at 37 °C for 20 min. Incubated
suspension was achieved [5,6]. Cell suspensions with a final cell concentration
of approximately 1×106/μl were used with a cell viability N96% as determined
by the trypan blue dye exclusion method. Some of them were co-cultured with
different concentrations of dexamethasone (10%, 20%, 30%, 40%, and 50%) in
96-well culture plate, compared with control groups (without dexamethasone).
Cell suspensions were transplanted within the striatum utilizing the
procedure described previously by Nikkhah and colleagues. Briefly, we
transplanted the desired number of cells, described as above, into the striatum
at the following coordinates (in millimeters, relative to bregma and the dural
surface) (1) AP: 0.5, L: 2.0, V: 4.6; (2) AP: 0.8, L: 4.0, V: 4.6 [7,8].
2.5. Post-transplant behavioural assessment
Functional recovery was assessed by apomorpine-induced (0.5 mg/kg)
rotational behavior using manual counter. Behavioural testing was carried out
every 2 weeks following transplantation.
2.6. Histological procedures
At 4 weeks post-transplantation, rats were deeply anesthetized with
pentobarbital (100 mg/kg) , then transcardially perfuse with 100 ml of cold
heparinized saline (0.9%) followed by 400 ml of cold 4% paraformaldehyde
for 6–8 h, then placed in 10% sucrose, 30% sucrose in PBS in turn. Following
equilibration, brains were sectioned on a freezing sliding microtome in 25-μm
thick sections, and stored at −20 °C.
Every five section was processed for tyrosine hydroxylase (TH) immuno-
histochemistry (Sigma 1: 1000) using the ABC solution and DAB for
visualization. The second series of sections was stained for glial fibrillary acid
protein (GFAP) immunohistochemistry (Sigma 1: 500). And the third series of
sections was stained for HE stain.
2.7. Cells counts and statistics
TH-immunoreactive graft neurons were counted microscopically in every
four section and an approximation of the final graft cell number was
calculated according to the formula of Abercrombie. Results are expressed as
means±SEM of the different treatment groups. For intergroup comparisons,
data were subjected to a one-factor analysis of variance (ANOVA), followed
by a q-test.
3.1. Cell culture in vitro
The FVM cells had been cultured in vitro for 7 days. The results
showed that there was no significant different between the two
Fig. 1. Photomicrographs of coronal sections through the grafted striatum of rat
processed immunocytochemically for TH. A significantly greater number of
total TH-ir cells (Pb0.001) was observed in the striatum of animals in group
treated with dexamethasone (A) than that in control group (B).
Fig. 2. Photomicrographs of coronal sections through the grafted striatum of rat
processed immunocytochemically for GFAP. A significantly greater number of
total TH-ir cells (Pb0.001) was observed in the striatum of animals in control
group (B) than that in group treated with dexamethasone (A).
127Y. Feng et al. / Transplant Immunology 18 (2007) 126–129
groups in the number and shape of TH-immunoreactive (TH-ir)
3.2. Rotational behavior
Animals were tested for rotational behaviour every weeks following
grafting. Compensation of rotational behaviour was observed 2 weeks
after graft in groups B and C. Four weeks after transplantation, group C
showed significant (Pb0.001) reduction in rotational asymmetry as
compared to group B, and both significant (Pb0.001) reduction as
compared to the group A.
3.3. Histological analyses
dopamine neurons of graft. GFAP immunohistochemistry was used to
mark the responsive astrocytes. HE staining was used to assess
inflammatory responses and infiltration of immune cells.
Surviving grafts were observed in both groups B and C, but not in
group A. A significantly greater number of total TH-ir cells (Pb0.001)
was observed in the striatum of animals in group C than that in group B
A significantly greater number of total GFAP-ir cells (Pb0.001)
was homogeneously scattered throughout the transplants in group B
when compared with that of the group C (Fig. 2). In HE staining, a
great number of inflammatory cells were observed in grafted area in
group B while this phenomenon was not seriously in group C (Fig. 3).
In group B, it was also found that inflammatory cells of closed ventricle
had a tendency to gather round to the area of transplantation
(chemotaxis) while it was not obviously in group C (Fig. 4).
4.1. Immune reaction in CNS
There are evidences that the xenografts and some allografts
displayed longer survival times and greater survival rates in the
brain than in other organs. So the brain was regarded as an
immunologically privileged transplantation site . The under-
lying reasons for this are not fully understood. Several
contributing factors have been suggested to favour long-term
survival of intracerebral neural grafts: the fact that there are
relatively few antigen-presenting cells present in the brain
parenchyma; paucity of direct drainage to the lymphatic system
from the brain interstitial space; a blood–brain barrier that may
donor neurons [3,10–12]. However, accumulating evidences
indicate that the CNS is only a selective immunological
privileged site. It also has a complicated mechanism of immune.
During the transplantation procedure, local blood–brain barrier
was destroyed by the surgery of transplantation. And it also lead
to temporary edema of brain, break of small blood vessel, tissue
injury, and local inflammatory responses and so on. All these
Fig. 4. Photomicrographs of coronal sections through the grafted striatum of rat
processed HE staining. Inflammatory cells of closed ventricle had a tendency to
gather round to the area of transplantation (chemotaxis) in control group
(B) while it was not obviously in group treated with dexamethasone (A).
Fig. 3. Photomicrographs of coronal sections through the grafted striatum of rat
processed HE staining. A great number of inflammatory cells were observed in
grafted area in control group (B) while this phenomenon was not seriously in
group treated with dexamethasone (A).
128Y. Feng et al. / Transplant Immunology 18 (2007) 126–129
could activate intrinsic microglial cell and astrocyte of brain
which have phagocytic and cleared abilities. In addition,
inflammatory stimulation could upregulate the level of adhesion
molecules on vasal endothelium which could help some
As stated above, we could conclude that local inflammatory and
immune response exist in transplantation areas and intracerebral
neural allografts can undergo rejection. Thus, immunosuppres-
sant should be used in order to overcome the immunological
problem in transplantation.
4.2. Effects of local injection of dexamethasone on immune
reaction in neural transplantation
In some studies and applications, immunosuppressant, such
as CyA, had been systemic administer in the pre- and post-
transplantation for a long time and its efficacy has already been
demonstrated in protecting the neural grafts from immunological
rejection. However, following the use of these drugs, many
problems also take place, such as high expense and serious side
effects. According to the characteristic of neural transplantation,
we suggest that local injection of dexamethasone may protect the
neural grafts from immunological rejection and improve the
success rate of graft. Dexamethasone is a synthetic adrenocortical
steroid, having powerful anti-inflammatory and immunosuppres-
sive effects. It can inhibit inflammation at both the early and late
and consequently fluid exudation, decreased accumulation of
lymphocyte activation, mediator synthesis and also by interfering
with the interaction of certain effector molecules with their target
cells. In addition, Dexamethasone can reduce edema and stabilize
of dexamethasone group there were fewer inflammation cells,
fewer response hyperplasia astrocytes and more survival grafted
DA neurons than those in non-dexamethasone injection group in
transplantation area. And the former also displayed significant
compared with the later. So these studies indicate that dexameth-
asone may play a role in reducing immune rejection in neural
In light of these findings, it is clear that immune rejection has
an effect on the survival of grafted cell in neural transplantation.
Local injection of dexamethasone could not only reduce the
immune rejection and increase the survival grafted cell but also
avoid the side effects brought by long systemic administer of
immunosuppressant. This finding is of some value for future use
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