PubMed Health⌕ Search

Biomedical subjects

Cecilia Lundberg

Publications and source records attributed to Cecilia Lundberg.

At least 19 recordsLinked to original sources
PubMed2006

Retrovirally delivered Islet-1 increases recruitment of Ng2 expressing cells from the postnatal SVZ into the striatum.

Neural stem and progenitor cells hold the promise to be used in cell-based therapies to treat both acute and degenerative neurological diseases. To date, most research has been focused on the use of in vitro propagated stem cells used as a source of cells in cell replacement therapies. However, mobilization of endogenous neural stem cells to generate a specific differentiated cell type offers an attractive alternative. In this study, we investigate the possibility to direct the formation of specific cells from the endogenous stem and progenitor cells residing in the subventricular region of the postnatal brain. With the aim to induce postnatal generation of striatal neurons, we ectopically expressed Islet-1, a LIM homeodomain transcription factor expressed by striatal progenitors during development, in cells of the subventricular zone (SVZ) of neonatal and adult rats. Ectopic expression of Islet-1 in the neonatal, but not adult, SVZ resulted in the appearance of a population of cells in the striatum. These cells were primarily located in the ventrolateral area of the striatum where they differentiate into Ng2 expressing cells. However, no neurogenesis was observed in the striatum, nor was ectopic striatal differentiation observed in any other area of the brain after retroviral expression of Islet-1 in the SVZ. Thus, although ectopic expression of Islet-1 is sufficient to direct the migration of cells into the striatum in neonatal animals, it does not specify a striatal projection neuron phenotype in cells generated from the SVZ after birth.

Animals↗
PubMed2006

Lentiviral vectors for use in the central nervous system.

Lentiviral vectors have been used extensively as gene transfer tools for the central nervous system throughout the past decade since they transduce most cell types in the brain, resulting in high-level and long-term transgene expression. This review discusses some of the recent progress in this field, including preclinical gene therapy experiments in disease models, development of regulated vectors, and the application of siRNA's using lentiviral vectors. We also describe some of the features that make lentiviral vectors a likely candidate for human gene therapy in the brain.

Animals↗
PubMed2006

Evidence for disease-regulated transgene expression in the brain with use of lentiviral vectors.

In this study we have developed and validated a novel approach of transgene regulation in the brain. By using lentiviral vectors that incorporate promoters of genes that are up-regulated during different pathological states, we were able to regulate transgene expression in accordance with the disease process. When using a glial fibrillary acidic protein promoter, efficient disease regulation in glial cells was achieved after an excitotoxic lesion or a 6-hydroxydopamine (6-OHDA) lesion. Transgene expression was physiologically regulated and displayed a dose-dependent increase depending on the severity of lesion. Efficient regulation was also achieved in neurons when using a preproenkephlin promoter in 6-OHDA-lesioned rats, allowing combined regulation and targeting. This disease-regulated approach allows control of transgene expression in the brain without the use of inducer molecules and without overexpression of transactivator proteins.

Animals↗
PubMed2005

A multivariate assessment of coastal eutrophication. Examples from the Gulf of Finland, northern Baltic Sea.

The Gulf of Finland is the sub-basin of the Baltic Sea that is most seriously affected by the effects and consequences of eutrophication. In this study, physical, chemical and biological long-term data (1980-2002) from the Finnish environmental monitoring programme is used to detect possible gradients of eutrophication in the Gulf. The Finnish coastal area of the Gulf of Finland is divided into three parts in an east-west direction, and into three zones (inner, middle, outer) according to differences in descriptive parameters. We use principal component analysis (PCA) to study spatial and temporal differences in relation to eutrophication. Clear differences between coastal and offshore areas are seen. Differences between eastern and western Gulf are not as evident. The changes due to eutrophication are larger for the inner archipelago, whereas the outer areas have been more stable over time. The concentration of oxygen is the strongest driving factor for eutrophication in the region.

Environmental Monitoring↗
PubMed2005

In vivo labeling of neuroblasts in the subventricular zone of rats.

The studies of neural stem cell fate, as well as the possibility to genetically manipulate them, represent important tools for modern neuroscience research. Furthermore, the potential use of these cells in treatment of neurological disorders makes these methods valuable for the development of new treatment paradigms. Here we report a method to genetically mark and modify neuroblasts and progenitor cells in the subventricular zone of post-natal rats using retroviral vectors. Using GFP as a marker gene we were able to follow the cells as they migrate and differentiate into olfactory interneurons. The cells were found in the olfactory bulb already 1 week after injection of the vector and after 3 weeks all cells had reached this area. There was a higher efficiency of the labeling of cells in neonatal rats compared to adults but injecting directly into the subventricular zone could to some extent counteract this effect. However, the cell types generated by the GFP positive cells were the same in neonatal and adult animals. This method will be a powerful tool to study the genetic interplay involved in neural stem cell differentiation and may be instrumental in finding a way to instruct these cells to participate in brain repair in the adult central nervous system.

Animals↗
PubMed2005

Ex vivo gene delivery of GDNF using primary astrocytes transduced with a lentiviral vector provides neuroprotection in a rat model of Parkinson's disease.

Astrocytes are, as normal constituents of the brain, promising vehicles for ex vivo gene delivery to the central nervous system. In the present study, we have used a lentiviral vector encoding glial cell line-derived neurotrophic factor (GDNF) to transduce rat-derived primary astrocytes, in order to evaluate their potential for long-term transgene expression in vivo and neuroprotection in a rat model of Parkinson's disease. Following transplantation of GDNF-transduced astrocytes to the intact striatum, the level of released GDNF was 2.93 +/- 0.28 ng/mg tissue at 1 week post-grafting, reduced to 0.42 +/- 0.12 ng/mg tissue at 4 weeks, and thereafter was maintained at this level throughout the experiment (12 weeks; 0.53 +/- 0.068 ng/mg tissue). Similarly, grafting to the substantia nigra (SN) resulted in a significant overexpression of GDNF ( approximately 0.20 ng/mg tissue) at 1 week. Intact animals receiving transplants of GDNF-transduced astrocytes displayed an increased contralateral turning (5.39 +/- 1.19 turns/min) in the amphetamine-induced rotation test, which significantly correlated with the GDNF tissue levels measured in the striatum, indicating a stimulatory effect of GDNF on the dopaminergic function. Transplantation of GDNF-transduced astrocytes to the SN 1 week prior to an intrastriatal 6-hydroxydopamine lesion provided a significant protection of nigral tyrosine hydroxylase-positive cells. By contrast, when the cells were transplanted to the striatum, the level of released GDNF was not sufficient to rescue the striatal fibers and, hence, to protect the nigral dopaminergic neurons. Overall, our results suggest that genetically modified astrocytes expressing GDNF can provide neuroprotection in a rat model of Parkinson's disease following transplantation to the SN.

Amphetamine↗
PubMed2005

Inhibition of chromatin condensation prevents transgene silencing in a neural progenitor cell line transplanted to the rat brain.

The use of ex vivo gene therapy in the central nervous system has so far suffered from transgene downregulation. Condensation of the transgenic sequences has been proposed to be a mechanism involved in this silencing. In this study we inhibited either histone deacetylation or DNA methylation in neural progenitor cell lines, transduced with a lentiviral vector carrying green fluorescent protein (GFP), prior to grafting them into the rat striatum. The expression of GFP was significantly higher in grafts pretreated with either of the inhibitors. After 1 week in vivo we detected an 11-fold increase in the number of GFP-expressing cells due to the inhibition of DNA methylation in vitro with azadeoxycytidine and a ninefold increase when inhibiting histone deacetylation with trichostatin A. This suggests that a pretreatment paradigm could be used to increase efficacy of ex vivo delivery of a therapeutic protein locally in the brain.

Animals↗
PubMed2005

Conceptualizing the Baltic Sea ecosystem: an interdisciplinary tool for environmental decision making.

There is an increasing call for stronger interdisciplinary studies in the Baltic Sea to find solutions to the environmental and social problems associated with eutrophication. Cooperation between experts from the natural sciences, socioeconomics, and management is needed. One way to solve communication problems is to develop a broad conceptual model that comprehensively describes eutrophication and links causes, effects, and the multiple relationships of eutrophication in a visual way. In the present conceptual model, the eutrophication process is divided into i) causes, ii) primary effects, iii) secondary effects, and iv) socioeconomic responses. Each part is described and discussed separately, with links to the other levels and compartments. Possible pathways are shown through the model from natural science to human society, thus inducing management options. Examples of key publications where the causes and effects are observed and studied in the Baltic Sea are listed as examples, and their implications are discussed.

Cooperative Behavior↗
PubMed2004

Dynamics of transgene expression in a neural stem cell line transduced with lentiviral vectors incorporating the cHS4 insulator.

Transplantation of genetically manipulated cells to the central nervous system holds great promise for the treatment of several severe neurological disorders. The success of this strategy relies on sufficient levels of transgene expression after transplantation. This has been difficult to achieve, however, due to transgene silencing. In this study, we transduced the neural stem cell line RN33B with self-inactivating lentiviral vectors and analyzed transgenic expression of green fluorescent protein (GFP) in several different settings both in vitro and after transplantation to the brain. We found that the transgene was affected of silencing both when transduced cells were proliferating and after differentiation. To prevent silencing, the cHS4 insulator was incorporated into the lentiviral vector. We found that a vector carrying the cHS4 insulator was partially protected against differentiation-dependent downregulation in vitro and in vivo. However, in proliferating cells, we found evidence for variegation and positional effects that were not prevented by the cHS4 insulator, suggesting that the mechanism behind silencing in proliferating cells is not the same mechanism influencing differentiation-dependent silencing. Taken together, these findings favor vector optimization as a strategy for achieving efficient ex vivo gene transfer in the central nervous system.

Animals↗
PubMed2004

Induction of neurites by the regulatory domains of PKCdelta and epsilon is counteracted by PKC catalytic activity and by the RhoA pathway.

We have shown that protein kinase C (PKC) epsilon, independently of its kinase activity, via its regulatory domain (RD), induces neurites in neuroblastoma cells. This study was designed to evaluate whether the same effect is obtained in nonmalignant neural cells and to dissect mechanisms mediating the effect. Overexpression of PKCepsilon resulted in neurite induction in two immortalised neural cell lines (HiB5 and RN33B). Phorbol ester potentiated neurite outgrowth from PKCepsilon-overexpressing cells and led to neurite induction in cells overexpressing PKCdelta. The effects were potentiated by blocking the PKC catalytic activity with GF109203X. Furthermore, kinase-inactive PKCdelta induced more neurites than the wild-type isoform. The isolated regulatory domains of novel PKC isoforms also induced neurites. Experiments with PKCdelta-overexpressing HiB5 cells demonstrated that phorbol ester, even in the presence of a PKC inhibitor, led to a decrease in stress fibres, indicating an inactivation of RhoA. Active RhoA blocked PKC-induced neurite outgrowth, and inhibition of the RhoA effector ROCK led to neurite outgrowth. This demonstrates that neurite induction by the regulatory domain of PKCdelta can be counteracted by PKCdelta kinase activity, that PKC-induced neurite outgrowth is accompanied by stress fibre dismantling indicating an inactivation of RhoA, and that the RhoA pathway suppresses PKC-mediated neurite outgrowth.

Actins↗
PubMed2004

Migratory capacity of the cell line RN33B and the host glial cell response after subretinal transplantation to normal adult rats.

As previously reported, the brain-derived precursor cell line RN33B has a great capacity to migrate when transplanted to adult brain or retina. This cell line is immortalized with the SV40 large T-antigen and carries the reporter gene LacZ and the green fluorescent protein GFP. In the present study, the precursor cells were transplanted to the subretinal space of adult rats and investigated early after grafting. The purpose was to demonstrate the migration of the grafted cells from the subretinal space into the retina and the glial cell response of the host retina. Detachment caused by the transplantation method was persistent up to 4 days after transplantation, and then reattachment occurred. The grafted cells were shown to migrate in between the photoreceptor cells before entering into the plexiform layers. Molecules involved in migration of immature neuronal cells as the polysialylated neural cell adhesion molecule (PSA-NCAM) and the collapsing response-mediated protein 4 (TUC-4) was found in the plexiform layers of the host retina, but not in the grafted cells. The expression of the intermediate filaments GFAP, vimentin, and nestin was intensely upregulated immediately after transplantation. A less pronounced upregulation was observed on sham-operated animals. In summary, the RN33B cell line migrated promptly posttransplantation and settled preferably into the plexiform layers of the retina, the same layers where the migration cues PSA-NCAM and TUC-4 were established. In addition, both the transplantation method per se and the implanted cells caused an intense glial cell response by the host retina.

Animals↗
PubMed2004

Regulated delivery of glial cell line-derived neurotrophic factor into rat striatum, using a tetracycline-dependent lentiviral vector.

In this study, a tetracycline-regulated lentiviral vector system, based on the tetracycline-dependent transactivator rtTA2(S)-M2, was developed for controlled expression of glial cell line-derived neurotrophic factor (GDNF) in the rat brain. Expression of the marker gene green fluorescent protein (GFP) and GDNF was tightly regulated in a dose-dependent manner in neural cell lines in vitro. Injection of high-titer lentiviral vectors into the rat striatum resulted in a 7-fold induction of GDNF tissue levels (1060 pg/mg tissue), when doxycycline (a tetracycline analog) was added to the drinking water. However, low levels of GDNF (150 pg/mg tissue) were also detected in animals that did not receive doxycycline, indicating a significant background leakage from the vector system in vivo. The level of basal expression was markedly reduced when a 10-fold lower dose of the tetracycline-regulated GDNF vector was injected into the striatum (3-11 pg/mg tissue), and doxycycline-induced GDNF tissue levels obtained in these animals were about 190 pg/mg tissue. Doxycycline-induced expression of GDNF resulted in a significant downregulation of the tyrosine hydroxylase (TH) protein in the intact striatum. Removal of doxycycline from the drinking water rapidly (within 3 days) turned off transgenic GDNF mRNA expression and GDNF protein levels in the tissue were completely reduced by 2 weeks, demonstrating the dynamics of the system in vivo. Accordingly, TH protein expression returned to normal by 2-8 weeks after removal of doxycycline, indicating that GDNF-induced downregulation of TH is a reversible event.

Animals↗
PubMed2004

Lesion-dependent regulation of transgene expression in the rat brain using a human glial fibrillary acidic protein-lentiviral vector.

The ability to regulate transgene expression will be crucial for development of gene therapy to the brain. The most commonly used systems are based on a transactivator in combination with a drug, e.g. the tetracycline-regulated system. Here we describe a different method of transgene regulation by the use of the human glial fibrillary acidic protein (GFAP) promoter. We constructed a lentiviral vector that directs transgene expression to astrocytes. Using toxin-induced lesions we investigated to what extent transgene expression could be regulated in accordance with the activation of the endogenous GFAP gene. In animals receiving excitotoxic lesions of the striatum we detected an eightfold increase of green fluorescent protein (GFP)-expressing cells. The vast majority of these cells did not divide, suggesting that the transgene was indeed regulated in a similar fashion as the endogenous GFAP gene. This finding will lead to the development of lentiviral vectors with autoregulatory capacities that may be very useful for gene therapy to the brain.

Animals↗
PubMed2004

Survival and long distance migration of brain-derived precursor cells transplanted to adult rat retina.

Neural precursor cells transplanted to adult retina can integrate into the host. This is especially true when the neural precursor rat cell line RN33B is used. This cell line carries the reporter genes LacZ and green fluorescent protein (GFP). In grafted rat eyes, RN33B cells are localized from one eccentricity to the other of the host retina. In the present study, whole-mounted retinas were analyzed to obtain a more appropriate evaluation of the amount of transgene-expressing cells and the migratory capacity of these cells 3 and 8 weeks post-transplantation. Quantification was made of the number of beta-galactosidase- and GFP-expressing cells with a semiautomatized stereological cell counting system. With the same system, delineation of the distribution area of the grafted cells was also performed. At 3 weeks, 68% of the grafted eyes contained marker-expressing cells, whereas at 8 weeks only 35% of the eyes contained such cells. Counting of marker-expressing cells demonstrated a lower number of transgene-expressing cells at 3 weeks compared with 8 weeks post-transplantation. The distribution pattern of marker gene-expressing cells revealed cells occupying up to 21% at 3 weeks and up to 68% at 8 weeks of the entire host retina post-grafting. The precursor cells survived well in the adult retina although the most striking feature of the RN33B cell line was its extraordinary migratory capacity. This capability could be useful if precursor cells are used to deliver necessary genes or gene products that need to be distributed over a large diseased area.

Animals↗
PubMed2003

Targeted transgene expression in rat brain using lentiviral vectors.

Direct gene transfer to the adult brain is dependent on vectors that transduce non-dividing cells, such as lentiviral vectors. Another aspect of the development of gene therapy to the brain is the need for cell-specific transgene expression. Expression from vesicular stomatitis virus G-protein (VSV-G) pseudotyped lentiviral vectors has been reported to be mainly neuron specific in the brain. We constructed cell-specific lentiviral vectors using the neuron-specific enolase (rNSE) or the glial fibrillary acidic protein (hGFAP) promoters and compared them to the ubiquitous human cytomegalovirus promoter (hCMV), a hybrid CMV/beta-actin promoter (CAG) and the promoter for human elongation factor 1 alpha (EF1 alpha). Our results showed that the hGFAP promoter was expressed only in glial cells, whereas rNSE was purely neuron specific, showing that VSV-G is pantropic in the rat striatum. We conclude that the VSV-G allows transduction of both glial and neuronal cells and the promoter dictates in what cell type the transgene will be expressed. The expression of transgenes exclusively in astrocytes would allow for local delivery of secreted transgene products, such as glial cell line-derived neurotrophic factor (GDNF), circumventing the anterograde transport that may induce unwanted side effects.

Analysis of Variance↗
PubMed2003

Hormone-sensitive lipase null mice exhibit signs of impaired insulin sensitivity whereas insulin secretion is intact.

Lipid metabolism plays an important role in glucose homeostasis under normal and pathological conditions. In adipocytes, skeletal muscle, and pancreatic beta-cells, lipids are mobilized from acylglycerides by the hormone-sensitive lipase (HSL). Here, the consequences of a targeted disruption of the HSL gene for glucose homeostasis were examined. HSL null mice were slightly hyperglycemic in the fasted, but not fed state, which was accompanied by moderate hyperinsulinemia. During glucose challenges, however, disposal of the sugar was not affected in HSL null mice, presumably because of release of increased amounts of insulin. Impaired insulin sensitivity was further indicated by retarded glucose disposal during an insulin tolerance test. A euglycemic hyperinsulinemic clamp revealed that hepatic glucose production was insufficiently blocked by insulin in HSL null mice. In vitro, insulin-stimulated glucose uptake into soleus muscle, and lipogenesis in adipocytes were moderately reduced, suggesting additional sites of insulin resistance. Morphometric analysis of pancreatic islets revealed a doubling of beta-cell mass in HSL null mice, which is consistent with an adaptation to insulin resistance. Insulin secretion in vitro, examined by perifusion of isolated islets, was not impacted by HSL deficiency. Thus, HSL deficiency results in a moderate impairment of insulin sensitivity in multiple target tissues of the hormone but is compensated by hyperinsulinemia.

Adipocytes↗
PubMed2003

Elevated GDNF levels following viral vector-mediated gene transfer can increase neuronal death after stroke in rats.

Previous studies have indicated that administration of glial cell line-derived neurotrophic factor (GDNF) counteracts neuronal death after stroke. However, in these studies damage was evaluated at most a few days after the insult. Here, we have explored the long-term consequences of two routes of GDNF delivery to the rat striatum prior to stroke induced by 30 min of middle cerebral artery occlusion (MCAO): striatal transduction with a recombinant lentiviral vector or transduction of the substantia nigra with a recombinant adeno-associated viral vector and subsequent anterograde transport of GDNF to striatum. Despite high GDNF levels, stereological quantification of striatal neuron numbers revealed no protection at 5 or 8 weeks after MCAO. In fact, anterograde GDNF delivery exacerbated neuronal loss. Moreover, supply of GDNF did not alleviate the striatum-related behavioral deficits. Thus, we demonstrate that the actions of GDNF after stroke are more complex than previously believed and that high levels of this factor, which are neuroprotective in models of Parkinson's disease, can increase ischemic damage. Our findings also underscore the need for quantitative assessment of long-term neuronal survival and behavioral changes to evaluate the therapeutic potential of factors such as GDNF.

Adenoviridae↗