Publications by authors named "Andreas Ratzka"

Parkinson's disease (PD) is pathologically characterized by the progressive loss of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc) and alpha-synucleinopathy. We mimic the disease pathology with overexpression of either the human α-syn wildtype (α-syn-WT) or E46K mutant form (α-syn-E46K) in DA neurons of the SNpc in adult rats using AAV2/DJ as a viral vector for the first time. Transduction efficiency was compared to an equal virus titer expressing the green fluorescent protein (GFP).

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The loss of nigral dopaminergic neurons and the resulting dopamine (DA) depletion in the striatum (STR) lead to altered neuronal activity and enhanced beta activity in various regions of the basal ganglia (BG) motor loop in patients with Parkinson's disease and in rodents in the 6-hydroxydopamine (6-OHDA)-lesioned rat model. Intrastriatal DA graft implantation has been shown to re-innervate the host brain and restore DA input. Here, DA cell grafts were implanted into the STR of 6-OHDA-lesioned rats and the effect on neuronal activity under urethane anesthesia (1.

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Several findings support the concept that sensorimotor integration is disturbed in Parkinson's disease (PD) and in levodopa-induced dyskinesias. In this study, we explored the neuronal firing activity of excitatory pyramidal cells and inhibitory interneurons in the forelimb region of the primary somatosensory cortex (S1FL-Ctx), along with its interaction with oscillatory activity of the primary motor cortex (MCtx) in 6-hydroxydopamine lesioned hemiparkinsonian (HP) and levodopa-primed dyskinetic (HP-LID) rats as compared to controls under urethane (1.4g/kg, i.

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Purpose: Innovative nerve conduits for peripheral nerve reconstruction are needed in order to specifically support peripheral nerve regeneration (PNR) whenever nerve autotransplantation is not an option. Specific support of PNR could be achieved by neurotrophic factor delivery within the nerve conduits via nanotechnology or stem cell engineering and transplantation.

Methods: Here, we comparatively investigated the bioactivity of selected neurotrophic factors conjugated to iron oxide nanoparticles (np-NTFs) and of bone marrow-derived stem cells genetically engineered to overexpress those neurotrophic factors (NTF-BMSCs).

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Human induced pluripotent stem cells (hiPSCs) are promising sources for regenerative therapies like the replacement of dopaminergic neurons in Parkinson's disease. They offer an unlimited cell source that can be standardized and optimized to produce applicable cell populations to gain maximal functional recovery. In the present study, human cord blood-derived iPSCs (hCBiPSCs) were differentiated into dopaminergic neurons utilizing two different in vitro protocols for neural induction: (protocol I) by fibroblast growth factor (FGF-2) signaling, (protocol II) by bone morphogenetic protein (BMP)/transforming growth factor (TGF-β) inhibition.

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Substitution of degenerated dopaminergic (DA) neurons by intrastriatally transplanted ventral mesencephalon (VM)-derived progenitor cells has been shown to improve motor functions in parkinsonian patients and animal models, whereas investigations of electrophysiological properties of the grafted DA neurons have been rarely performed. Here we show electrophysiological properties of grafted VM progenitor cells at different time intervals up to 12 weeks after transplantation measured in acute brain slices using eGFP-Flag transfection to identify the graft. We were able to classify typical DA neurons according to the biphasic progression (voltage "sag") to hyperpolarizing current injections.

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Nuclear bodies are large sub-nuclear structures composed of RNA and protein molecules. The Survival of Motor Neuron (SMN) protein localizes to Cajal bodies (CBs) and nuclear gems. Diminished cellular concentration of SMN is associated with the neurodegenerative disease Spinal Muscular Atrophy (SMA).

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Tactile stimulation (TS) applied to adult rats after cortical injury (medial frontal cortex aspiration or sensorimotor pial stripping stroke model) has been previously shown to ameliorate behavioral impairments and to improve morphological parameters like dendritic length of prefrontal cortical neurons (Gibb et al., 2010). The purpose of this study was to examine the effect of TS on healthy and hemiparkinsonian adult rats.

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Biosynthetic nerve grafts are desired as alternative to autologous nerve grafts in peripheral nerve reconstruction. Artificial nerve conduits still have their limitations and are not widely accepted in the clinical setting. Here we report an analysis of fine-tuned chitosan tubes used to reconstruct 10 mm nerve defects in the adult rat.

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Dopamine (DA) depletion in the nigrostriatal system leads to basal ganglia dysfunction both in Parkinson's disease (PD) and in 6-hydroxy dopamine (6-OHDA)-lesioned rats with neuronal hyperactivity in the subthalamic nucleus (STN), i.e. increased firing rate and burst activity, together with enhanced beta oscillatory activity.

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Reduced levels of survival of motoneuron (SMN) protein lead to spinal muscular atrophy, but it is still unknown how SMN protects motoneurons in the spinal cord against degeneration. In the nucleus, SMN is associated with two types of nuclear bodies denoted as gems and Cajal bodies (CBs). The 23 kDa isoform of fibroblast growth factor-2 (FGF-2(23)) is a nuclear protein that binds to SMN and destabilizes the SMN-Gemin2 complex.

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Fibroblast growth factor 2 (FGF-2) is an important neurotrophic factor that promotes survival of adult mesencephalic dopaminergic (mDA) neurons and regulates their adequate development. Since mDA neurons degenerate in Parkinson's disease, a comprehensive understanding of their development and maintenance might contribute to the development of causative therapeutic approaches. The current analysis addressed the role of FGF-2 in mDA axonal outgrowth, pathway formation, and innervation of respective forebrain targets using organotypic explant cocultures of ventral midbrain (VM) and forebrain (FB).

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Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by selective motoneuron loss in brain and spinal cord. Mutations in the superoxide dismutase (SOD) 1 gene account for 10-20% of familial ALS patients. The ALS-mouse model over-expressing a mutant human SOD1 (G93A) gene closely mimics human ALS disease.

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FGF Receptor-1 (FGFR1), a membrane-targeted protein, is also involved in independent direct nuclear signaling. We show that nuclear accumulation of FGFR1 is a common response to retinoic acid (RA) in pluripotent embryonic stem cells (ESC) and neural progenitors and is both necessary and sufficient for neuronal-like differentiation and accompanying neuritic outgrowth. Dominant negative nuclear FGFR1, which lacks the tyrosine kinase domain, prevents RA-induced differentiation while full-length nuclear FGFR1 elicits differentiation in the absence of RA.

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Fibroblast growth factor 2 (FGF-2) is a neurotrophic factor participating in regulation of proliferation, differentiation, apoptosis and neuroprotection in the central nervous system. With regard to dopaminergic (DA) neurons of substantia nigra pars compacta (SNpc), which degenerate in Parkinson's disease, FGF-2 improves survival of mature DA neurons in vivo and regulates expansion of DA progenitors in vitro. To address the physiological role of FGF-2 in SNpc development, embryonic (E14.

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Experiments in mice deficient for Nurr1 or expressing the dominant-negative FGF receptor (FGFR) identified orphan nuclear receptor Nurr1 and FGFR1 as essential factors in development of mesencephalic dopaminergic (mDA) neurons. FGFR1 affects brain cell development by two distinct mechanisms. Activation of cell surface FGFR1 by secreted FGFs stimulates proliferation of neural progenitor cells, whereas direct integrative nuclear FGFR1 signaling (INFS) is associated with an exit from the cell cycle and neuronal differentiation.

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The monogenetic disease Spinal Muscular Atrophy (SMA) is characterized by a progressive loss of motoneurons leading to muscle weakness and atrophy due to severe reduction of the Survival of Motoneuron (SMN) protein. Several models of SMA show deficits in neurite outgrowth and maintenance of neuromuscular junction (NMJ) structure. Survival of motoneurons, axonal outgrowth and formation of NMJ is controlled by neurotrophic factors such as the Fibroblast Growth Factor (FGF) system.

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Exogenous cell replacement represents a potent treatment option for Parkinson's disease. However, the low survival rate of transplanted dopaminergic neurons (DA) calls for methodological improvements. Here we evaluated a method to combine transient genetic modification of neuronal progenitor cells with an optimized cell culture protocol prior to intrastriatal transplantation into 6-hydroxydopamine (6-OHDA) unilateral lesioned rats.

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Secreted proteins of the fibroblast growth factor (FGF) family play important roles during development of various organ systems. A detailed knowledge of their temporal and spatial expression profiles, especially of closely related FGF family members, are essential to further identification of specific functions in distinct tissues. In the central nervous system dopaminergic neurons of the substantia nigra and their axonal projections into the striatum progressively degenerate in Parkinson's disease.

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Short-term low-frequency electrical stimulation (ESTIM) of proximal peripheral nerve stumps prior to end-to-end coaptation or tubular bridging of small distances has been reported to increase preferential motor reinnervation and functional motor recovery in animal models and human patients undergoing carpal tunnel release surgery. We investigated the effects of ESTIM on regeneration across rat sciatic nerve gaps, which exceed distances that allow spontaneous regeneration. Three different reconstruction approaches were combined with ESTIM in the experimental groups.

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Many Parkinson's disease (PD) patients suffer from anxiety disorders, which often precede the onset of classical motor symptoms. So far, there is no evidence from randomized, placebo-controlled trials for successful treatment of anxiety in patients with PD. Grafts of fetal nigral neurons are currently explored as a restorative cell therapy for PD.

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Mammalian sulfatase enzymes participate in various processes, such as hormone regulation, lysosomal degradation and modulation of several signaling pathways. The sulfatase gene family consists of 14 members in mice and 17 in humans. Mutations of at least eight members are associated with human disorders, with main disease manifestations in the nervous system and skeleton.

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Neuronal progenitor cells (NPCs) possess high potential for use in regenerative medicine. To overcome their limited mitotic competence, various immortalization strategies have been applied that allow their prolonged maintenance and expansion in vitro. Such immortalized cells can be used for the design and discovery of new cell-based therapies for neurodegenerative diseases, such as Parkinson's disease.

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Neurotrophic factors have been shown to stimulate and support peripheral nerve repair. One of these factors is basic fibroblast growth factor (FGF-2), which is up-regulated after peripheral nerve injury and influences early sciatic nerve regeneration by regulating Schwann cell proliferation. Our previous study on FGF-2 deficient mice indicated that FGF-2 is important for axonal maturation and remyelination one week after sciatic nerve crush (Jungnickel, J.

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Modification of the sulfation pattern of heparan sulfate (HS) during organ development is thought to regulate binding and signal transduction of several growth factors. The secreted sulfatases, Sulf1 and Sulf2, desulfate HS on 6-O-positions extracellularly. We show that both sulfatases are expressed in overlapping patterns during embryonic skeletal development.

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