Papers by Francisco Diaz-Corrales
Stem Cells, Apr 24, 2013
Retinitis pigmentosa (RP), a genetically heterogeneous group of diseases together with age-relate... more Retinitis pigmentosa (RP), a genetically heterogeneous group of diseases together with age-related macular degeneration (AMD), are the leading causes of permanent blindness and are characterized by the progressive dysfunction and death of the light sensing photoreceptors of the retina. Due to the limited regeneration capacity of the mammalian retina, the scientific community has invested significantly in trying to obtain retinal progenitor cells from embryonic stem cells (ESC). These represent an unlimited source of retinal cells, but it has not yet been possible to achieve specific populations, such as photoreceptors, efficiently enough to allow them to be used safely in the future as cell therapy of RP or AMD. In this study, we generated a high yield of photoreceptors from directed differentiation of mouse ESC (mESC) by recapitulating crucial phases of retinal development. We present a new protocol of differentiation, involving hypoxia and taking into account extrinsic and intrinsic cues. These include niche-specific conditions as well as the manipulation of the signaling pathways involved in retinal development. Our results show that hypoxia promotes and improves the differentiation of mESC toward photoreceptors. Different populations of retinal cells are increased in number under the hypoxic conditions applied, such as Crxpositive cells, S-Opsin-positive cells, and double positive cells for Rhodopsin and Recoverin, as shown by immunofluorescence analysis. For the first time, this manuscript reports the high efficiency of differentiation in vivo and the expression of mature rod photoreceptor markers in a large number of differentiated cells, transplanted in the subretinal space of wild-type mice. STEM CELLS 2013;31:966-978 Disclosure of potential conflicts of interest is found at the end of this article.
Human Gene Therapy Methods, Apr 1, 2016
Diabetic retinopathy (DR) is one of the major complications of Diabetes mellitus. It is character... more Diabetic retinopathy (DR) is one of the major complications of Diabetes mellitus. It is characterized by retinal microvascular changes caused by chronic exposure to hyperglycemia, leading to low tissue oxygenation and ultimately to neovascularization. Laser photocoagulation and vitrectomy are the most efficient treatments for DR, but display severe side effects such as the destruction of the healthy retina. Another clinical approach uses anti-angiogenic agents to prevent and delay progression of neovascularization, but these require recurrent local administrations which increase the possibility of retinal detachment, vitreous hemorrhage, and cataract formation. Studies in human diabetic retinas have revealed an imbalance between pro-angiogenic factors such as the vascular endothelial growth factor (VEGF) and anti-angiogenic factors, like pigment epithelial-derived factor (PEDF). This imbalance favors pathological angiogenesis contributing to DR, and can constitute a therapeutic target. Gene therapy was recently shown to be an adequate intervention for long-term treatment of several retinal pathologies. We have previously shown the newly engineered episomal vector pEPito to be able of sustained gene expression in the mouse retina. We here show that pEPito was able to overexpress PEDF for up to three months, both in in vitro cultures of human RPE cells, as well as in the retina of diabetic mice after a single subretinal injection. In vivo, in parallel with the increase in PEDF we observed a decrease in VEGF levels in injected compared with non-injected eyes and a significant effect on two hallmarks of DR: reduction of glucose transport (by glucose transporter GLUT1), and reduction of inflammation by decreased reactivity of microglia. Jointly, these results point to a significant therapeutic potential of gene therapy with pEPito-PEDF for the treatment of DR.
Investigative Ophthalmology & Visual Science, Apr 30, 2014
Investigative Ophthalmology & Visual Science, Jun 11, 2015
Investigative Ophthalmology & Visual Science, Sep 26, 2016
Clinical Neuropharmacology, Jul 1, 2005
The neurotoxicity of dopamine (DA) quinones that appears in dopaminergic neuron-specific oxidativ... more The neurotoxicity of dopamine (DA) quinones that appears in dopaminergic neuron-specific oxidative stress has recently been shown to play a role in the pathogenesis and/or progression of Parkinson disease. To clarify the effects of a DA agonist, pergolide, on the levodopa-induced elevation of quinones, the authors examined striatal changes in quinoprotein using a hemi-parkinsonian mouse model. The level of striatal quinoprotein was significantly elevated specifically on the parkinsonian side, but not on the control side, after repeated levodopa administration. This levodopa-induced increase in striatal quinoprotein was almost completely suppressed by adjunctive administration with pergolide on the lesioned side. Furthermore, it was clarified that pergolide scavenged DA-semiquinones generated in vitro in a dose-dependent manner. These suppressive and quenching effects of pergolide against cytotoxic DA quinones may play a key role in its neuroprotective mechanism in the parkinsonian brain.
Movement Disorders, Jun 2, 2011
Sensory symptoms are common nonmotor manifestations of Parkinson's disease. It has been hypot... more Sensory symptoms are common nonmotor manifestations of Parkinson's disease. It has been hypothesized that abnormal central processing of sensory signals occurs in Parkinson's disease and is related to dopaminergic treatment. The objective of this study was to investigate the alterations in sensory perception induced by transcranial magnetic stimulation of the primary somatosensory cortex in patients with Parkinson's disease and the modulatory effects of dopaminergic treatment. Fourteen patients with Parkinson's disease with and without dopaminergic treatment and 13 control subjects were included. Twenty milliseconds after peripheral electrical tactile stimuli in the contralateral thumb, paired‐pulse transcranial magnetic stimulation over the right primary somatosensory cortex was delivered. We evaluated the perception of peripheral electrical tactile stimuli at 2 conditioning stimulus intensities, set at 70% and 90% of the right resting motor threshold, using different interstimulus intervals. At 70% of the resting motor threshold, paired‐pulse transcranial magnetic stimulation over the right primary somatosensory cortex induced an increase in positive responses at short interstimulus intervals (1–7 ms) in controls but not in patients with dopaminergic treatment. At 90% of the resting motor threshold, controls and patients showed similar transcranial magnetic stimulation effects. Changes in peripheral electrical tactile stimuli perception after paired‐pulse transcranial magnetic stimulation over the primary somatosensory cortex are altered in patients with Parkinson's disease with dopaminergic treatment compared with controls. These findings suggest that primary somatosensory cortex excitability could be involved in changes in somatosensory integration in Parkinson's disease with dopaminergic treatment. © 2011 Movement Disorder Society
Annals of Neurology, Feb 1, 2010
Revista de la Sociedad Venezolana de Microbiología, 2003
CNS Neuroscience & Therapeutics, Jan 25, 2018
Neuroscience Letters, 2004
It has been reported that the Golgi apparatus (GA) is fragmented in some neurodegenerative diseas... more It has been reported that the Golgi apparatus (GA) is fragmented in some neurodegenerative diseases. However, the significance of the GA fragmentation or disassembly in neurodegeneration is still obscure. To clarify the involvement of this organelle in apoptosis of neuronal cells, we examined the morphological changes in the GA induced by rotenone, a pesticide that produces selective dopaminergic neurodegeneration. In dopaminergic neuroblastoma B65 cells, a 5-day rotenone treatment (50 nM) promoted cell damage. Rotenonetreated cells showed round nuclei, diffuse signals of the GA and cytosolic redistribution of cytochrome c. Nevertheless, these type of cells without nuclear fragmentation did not show any caspase-3 expression. These results indicate that rotenone induces disassembly of the GA in the early stages of the apoptotic process.
The FASEB Journal, Jan 10, 2006
Brain Stimulation, Jul 1, 2013
Although functional changes in the activation of the cerebellum in Parkinson&amp;amp;amp;amp;... more Although functional changes in the activation of the cerebellum in Parkinson&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s disease (PD) patients have been consistently described, it is still debated whether such altered cerebellar activation is a natural consequence of PD pathophysiology or rather it involves compensatory mechanisms. We used different forms of cerebellar transcranial magnetic stimulation to evaluate the hypothesis that altered cerebello-cortical interactions can be observed in PD patients and to evaluate the role of dopaminergic treatment. We studied the effects of a single cerebellar magnetic pulse over the excitability of the contralateral primary motor cortex tested with motor-evoked potentials (MEPs) (cerebellar-brain inhibition-CBI) in a group of 16 PD patients with (ON) and without dopaminergic treatment (OFF), and in 16 age-matched healthy controls. Moreover, we also tested the effects of cerebellar continuous theta-burst stimulation (cTBS) on MEP amplitude, short intracortical inhibition (SICI) and short intracortical facilitation (SICF) tested in the contralateral M1 in 13 PD patients in ON and OFF and in 16 age-matched healthy controls. CBI was evident in controls but not in PD patients, even when tested in both ON and OFF conditions. Similarly, cerebellar cTBS reduced MEP amplitude and SICI in controls but not in PD patients under any condition. These results demonstrate that PD patients have deficient short-latency and long-lasting cerebellar-thalamocortical inhibitory interactions that cannot be promptly restored by standard dopaminergic medication.
Neurotoxicity Research, Dec 1, 2008
Human Molecular Genetics, Jan 7, 2013
Ataxia-telangiectasia and Rad3 (ATR), a sensor of DNA damage, is associated with the regulation a... more Ataxia-telangiectasia and Rad3 (ATR), a sensor of DNA damage, is associated with the regulation and control of cell division. ATR deficit is known to cause Seckel syndrome, characterized by severe proportionate short stature and microcephaly. We used a mouse model for Seckel disease to study the effect of ATR deficit on retinal development and function and we have found a new role for ATR, which is critical for the postnatal development of the photoreceptor (PR) layer in mouse retina. The structural and functional characterization of the ATR 1/s mouse retinas displayed a specific, severe and early degeneration of rod and cone cells resembling some characteristics of human retinal degenerations. A new localization of ATR in the cilia of PRs and the fact that mutant mice have shorter cilia suggests that the PR degeneration here described results from a ciliary defect.
Brain Research, Dec 1, 2004
Expression of dopamine receptors (DA-Rs) in astrocytes was examined in vitro and in vivo using pr... more Expression of dopamine receptors (DA-Rs) in astrocytes was examined in vitro and in vivo using primary cultured astrocytes and brain slices from rat basal ganglia. Astrocytes from basal ganglia expressed DA D1-, D3-, D4- and D5-receptors and D4-mediated signal transduction in response to DA, suggesting possible involvement of astrocytes in the pharmacological action of atypical antipsychotic drugs and in DA response in some neurological diseases.
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Papers by Francisco Diaz-Corrales