Jiang-Chuan Liu

siRNA-targeting transforming growth factor-β type I receptor reduces wound scarring and extracellular matrix deposition of scar tissue.

Hypertrophic scarring is related to persistent activation of transforming growth factor-β (TGF-β)/Smad signaling. In the TGF-β/Smad signaling cascade, the TGF-β type I receptor (TGFBRI) phosphorylates Smad proteins to induce fibroblast proliferation and extracellular matrix deposition. In this study, we inhibited TGFBRI gene expression via TGFBRI small interfering RNA (siRNA) to reduce fibroblast proliferation and extracellular matrix deposition. Our results demonstrate that downregulating TGFBRI expression in cultured human hypertrophic scar fibroblasts significantly suppressed cell proliferation and reduced type I collagen, type III collagen, fibronectin, and connective tissue growth factor (CTGF) mRNA, and type I collagen and fibronectin protein expression. In addition, we applied TGFBRI siRNA to wound granulation tissue in a rabbit model of hypertrophic scarring. Downregulating TGFBRI expression reduced wound scarring, the extracellular matrix deposition of scar tissue, and decreased CTGF and α-smooth muscle actin mRNA expression in vivo. These results suggest that TGFBRI siRNA could be applied clinically to prevent hypertrophic scarring.

Dual SPECT of dopamine system using [99mTc]TRODAT-1 and [123I]IBZM in normal and 6-OHDA-lesioned formosan rock monkeys

Parkinsons disease (PD) is a progressive neurodegenerative disorder characterized by a severe loss of the dopaminergic neurons in the substantia nigra pars compacta. In this study, we evaluated pre- and post-synaptic binding sites of the dopamine system in three normal and one parkinsonian monkeys using simultaneous [99mTc]TRODAT-1 and [123I]IBZM imaging. The parkinsonian monkey was induced by injecting 6-hydroxydopamine (6-OHDA) bilaterally into the medial forebrain bundle under MRI guidance. [99mTc]TRODAT-1 (targeting dopamine transporters) and [123I]IBZM (targeting D(2)/D(3) receptors) were administered almost simultaneously and the SPECT images were acquired over 4 h using a dual-headed gamma camera equipped with ultra-high resolution fan-beam collimators. Data were obtained using energy window of 15% centered on 140 keV for 99mTc in conjunction with 10% asymmetric energy window in a lower bound at 159 keV for 123I. Single SPECT studies of [99mTc]TRODAT-1 and [123I]IBZM were also performed. We found a comparable image quality and uptake ratios between single- and dual-isotope studies. There are higher TRODAT-1 uptakes in the control monkeys than the 6-OHDA-lesioned monkey. The uptake of [123I] IBZM showed no significant difference between controls and 6-OHDA-lesioned monkey. Our results suggest that dual isotope imaging using [99mTc]TRODAT-1 and [123I]IBZM may be a useful means in evaluating the changes of both pre- and post-synaptic dopamine system in a primate model of parkinsonism.

Validation of 4-[18F]-ADAM as a SERT imaging agent using micro-PET and autoradiography.

Serotonin transporters (SERTs) have been implicated in various neuropsychiatric disorders. We aim to validate 4-[(18)F]-ADAM (N,N-dimethyl-2-(2-amino-4-[(18)F]fluorophenylthio)benzylamine) as a SERT imaging agent in rats using micro-positron emission tomography (micro-PET) and autoradiography. Sixty to ninety min after injecting 4-[(18)F]-ADAM, specific uptake ratios (SURs) were determined by micro-PET measurements in various brain regions of normal control rats. For n=3, the SUR in the midbrain was 4.94+/-0.16, for the hypothalamus it was 4.39+/-0.031 and for the caudate it was 4.18+/-0.53. The retention of 4-[(18)F]-ADAM in the hypothalamus and midbrain regions increased rapidly between 5 to 10 min after injection and declined thereafter. The SURs determined by autoradiography were: 9.31+/-1.41 for the midbrain, 7.15+/-1.45 for the hypothalamus and 5.22+/-1.14 for the caudate putamen. Both micro-PET and autoradiography studies revealed a dose-dependent progressive inhibition of radioligand uptake in the frontal cortex, caudate putamen and hypothalamus in rats treated with 0.01 to 0.25 mg/kg paroxetine. A decrease in 4-[(18)F]-ADAM uptake of approximately 84% was observed in the midbrain of rats pretreated with 0.25 mg/kg paroxetine as compared to controls (4.94+/-0.16 versus 0.80+/-0.17, n=3). Both 5,7-dihydroxytryptamine and p-chloroamphetamine-treated rats showed pronounced reduction in 4-[(18)F]-ADAM binding when compared to normal controls. Rats pretreated with p-chloroamphetamine exhibited significant inhibition of 4-[(18)F]-ADAM uptake in brain regions rich in SERT over a period of four weeks. Thus, 4-[(18)F]-ADAM is a SERT-specific radioligand that may be useful for evaluating neuropsychiatric conditions involving serotonergic dysfunction.

Effects of interleukin-15 on neuronal differentiation of neural stem cells.

Interleukin-15 (IL-15) signaling has pleiotropic actions in many cell types during development and has been best studied in cells of immune system lineage, where IL-15 stimulates proliferation of cytotoxic T cells and induces maturation of natural killer cells. A few reports have indicated that IL-15 and the IL-15 receptor are expressed in central nervous system tissues and neuronal cell lines. Because this aspect of IL-15 action is poorly studied, we used cultured rat neural stem cells (NSCs) to study IL-15 signal transduction and activity. Primary cultures of rat NSCs in culture will form neurospheres and will differentiate into neuron, astrocyte, and oligodendrocyte progenitors under permissive conditions. We found by immunofluorescence that the IL-15Ralpha subunit of the IL-15 receptor was expressed in NSCs and differentiating neurons, but not astrocyte or oligodendrocyte progenitors. We also showed that IL-15 treatment reduced MAP-2 protein levels in neurons and could reduce neurite outgrowth in differentiating neurons but did not affect NSC proliferation, and cell proportions and viability of the corresponding lineage cells. In the presence of a STAT3 inhibitor, Stattic, IL-15 no longer reduced MAP-2 protein levels. IL-15 treatment caused STAT3 phosphorylation. Furthermore, using anti-IL-15Ralpha antibody to block IL-15 signaling completely inhibited IL-15-induced phosphorylation of STAT3 and prevented IL-15 from decreasing neurite outgrowth. In conclusion, IL-15 may influence neural cell differentiation through a signal transduction pathway involving IL-15Ralpha and STAT3. This signal transduction modifies MAP-2 protein levels and, consequently, the differentiation of neurons from NSCs, as evidenced by reduced neurite outgrowth.

Potent, hydroxyl radical-scavenging effect of apomorphine with iron and dopamine perfusion in rat striatum

In dopaminergic neurons, free radicals are likely produced via dopamine metabolism by monoamine oxidase or via its auto-oxidation, a process facilitated by transition metals. In this study we examined the effect and possible mechanisms of apomorphine to reduce iron- and dopamine-induced 2,3-dihydroxybenzoic acid (2,3-DHBA) formation by microdialysis. We have shown that (1) FeSO(4).7H(2)O reduced both the release of dopamine and the output of dihydroxyphenylacetic acid (DOPAC); (2) apomorphine may reduce FeSO(4).7H(2)O-induced increases of 2,3-DHBA formation; (3) apomorphine has substantially reduced DOPAC output in early phase and blocked dopamine-induced increase of 2,3-DHBA levels. It is concluded that apomorphine is a potent hydroxyl radical scavenger in vivo, especially for the dopamine formation.

Intrastriatal transplantation of Sertoli cells may improve amphetamine-induced rotation and tyrosine hydroxylase immunoreactivity of the striatum in hemiparkinsonian rats

This study investigated survival and neurotrophic effects of Sertoli cells transplanted in the striatum of 6-hydroxydopamine (6-OHDA)-induced hemiparkinsonian rats. Primary cultures of Sertoli cells were established from 3-week old rats and characterized by associated marker, placental cadherin (P-cadherin). Two months after transplantation, amphetamine-induced rotations of rats transplanted with Sertoli cells were significantly lower than those of control rats. However, restoration of tyrosine hydroxylase (TH) immunoreactivity and Sertoli cells that expressed P-cadherin were only found in the striatum of the rat that showed full recovery from amphetamine-induced rotation 3 months after transplantation without immunosuppression. These results suggest that Sertoli cells transplanted in striatum of hemiparkinsonian rats may survive for at least 3 months, and improve amphetamine-induced rotation and restore TH immunoreactivity.

Imaging serotonin transporters using [123I]ADAM SPECT in a parkinsonian primate model

Parkinsons disease (PD) affects multiple neurotransmitter systems. The purpose of this study was to investigate differences in the serotonin transport system between normal and parkinsonian monkeys using 2-([2-([di-methylamino]methyl)phenyl]thio)-5-[(123)I] iodophenyl-amine([(123)I]ADAM), a serotonin transporters (SERT) radioligand. The brain single photon emission computed tomography (SPECT) was performed on two normal and one parkinsonian monkey. The parkinsonian monkey was induced by bilateral injection of 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle under magnetic resonance imaging (MRI) guidance. Each monkey underwent two [(99m)Tc] TRODAT-1 (a dopamine transporters imaging agent) and two [(123)I] ADAM brain SPECT scans. After a bolus injection of the radioligand, the SPECT data were acquired over 4h using a dual-head gamma camera equipped with ultra-high resolution fan-beam collimators. The striatal uptake of [(99m)Tc]TRODAT-1 was 46% lower in the parkinsonian monkey than those of normal monkeys at 210-240 min post-injection. [(123)I]ADAM uptake in the midbrain of the parkinsonian monkey was comparable to those of the controls. The uptakes of [(123)I]ADAM in the striatum, thalamus, and frontal cortex of the parkinsonian monkey, were 31%, 31%, and 23% lower than those of normal monkeys at 210-240 min post-injection, respectively. Our results suggest that [(123)I]ADAM SPECT has potential for evaluating the serotonin transporter changes in human PD.

The role of dopamine transporter imaging agent [99mTc]TRODAT-1 in hemi-parkinsonism rat brain.

This study aims to investigate the relationship between the determination of dopamine level by high performance liquid chromatography (HPLC) with electrochemical detection (ECD) and the detection of dopamine transporter (DAT) counts using autoradiography with DAT image agent [99mTc]TRODAT-1. For striatal lesions, pretreatment of 6-hydroxydopamine (6-OHDA) in the medial forebrain bundle shows that autoradiogaphic labeling of striatum region is reduced to near-background level. Using HPLC with ECD, unilateral 6-OHDA treatment is associated with significant (p < 0. 0002) reductions of dopamine levels. For the striatum of the 6-OHDA-lesioned side, dopamine content and DAT counts are reduced to 97% and 90%, respectively. Thus, our observation indicates a potential of using [99mTc]TRODAT-1 for the evaluation of animal DAT.

Adeno-associated virus-mediated human acidic fibroblast growth factor expression promotes functional recovery of spinal cord–contused rats

Following spinal cord injury, the delivery of neurotrophic factors to the injured spinal cord has been shown to promote axonal regeneration and functional recovery. In previous studies, we showed that acidic fibroblast growth factor (aFGF) is a potent neurotrophic factor that promotes the regeneration of axotomized spinal cord or dorsal root ganglion neurones.

Dual-isotope single-photon emission computed tomography for dopamine and serotonin transporters in normal and parkinsonian monkey brains

INTRODUCTION Parkinsons disease (PD) affects both dopaminergic and serotonergic systems. In this study, we simultaneously evaluated dopamine and serotonin transporters in primates using dual-isotope single-photon emission computed tomography (SPECT) imaging and compared the results with traditional single-isotope imaging. METHODS Four healthy and one 6-OHDA-induced PD monkeys were used for this study. SPECT was performed over 4 h after individual or simultaneous injection of [(99m)Tc]TRODAT-1 (a dopamine transporter imaging agent) and [(123)I]ADAM (a serotonin transporter imaging agent). RESULTS The results showed that the image quality and uptake ratios in different brain regions were comparable between single- and dual-isotope studies. The striatal [(99m)Tc]TRODAT-1 uptake in the PD monkey was markedly lower than that in normal monkeys. The uptake of [(123)I]ADAM in the midbrain of the PD monkey was comparable to that in the normal monkeys, but there were decreased uptakes in the thalamus and striatum of the PD monkey. CONCLUSIONS Our results suggest that dual-isotope SPECT using [(99m)Tc]TRODAT-1 and [(123)I]ADAM can simultaneously evaluate changes in dopaminergic and serotonergic systems in a PD model.