Honors & Awards
NEI Vision Core grant funding, National Eye Institute (2018/03-2018/06)
Translational Research and Applied Medicine (TRAM) Pilot Grant, Stanford (2018-2019)
PAPD Scholarship, Capes/FAPERJ (Brazil) (2016-2017)
Science Without Borders Scholarship (Visitor Graduate Student), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq Brazil) (2013-2014)
BRAVO/Allergan prize, Experimental Biology Societies Federation (FeSBE) (2009)
Doctor of Philosophy, Universidade Federal Rio De Janeiro (2015)
Master of Science, Universidade Federal Rio De Janeiro (2011)
Bachelor of Science, Universidade Federal Rio De Janeiro (2008)
Current Research and Scholarly Interests
Interested in understanding how glia shapes neuronal fate in neurodegenerative diseases and in designing therapeutic approaches to prevent retinal ganglion cell loss and irreversible damage to the optic nerve, the only connection between the eye and the brain.
Currently researching the impact of hypoxic-ischemic injury to the visual pathway due to systemic hypoxia or ischemic optic neuropathy. Hypoxic (low oxygen), ischemic (low blood flow) injury is common in all age groups and can occur as a result of perinatal asphyxiation in babies; near-drowning and poisoning in children; or cardiac arrest, stroke, pulmonary diseases, peri-operative complications, high altitude exposure, and space travel in adults. Anterior ischemic optic neuropathy is the most common cause of sudden vision loss in those older than 50. I am currently investigating the impact of hypoxic-ischemic conditions in the metabolic stress and gliosis in the visual pathway.
Other interests and experience: cell therapies with adult stem cells; disease modeling using induced pluripotent stem cells; oligodendroglia generation and biology.
Systemic hypoxia led to little retinal neuronal loss and dramatic optic nerve glial response.
Experimental eye research
Vision loss is a devastating consequence of systemic hypoxia, but the cellular mechanisms are unclear. We investigated the impact of acute hypoxia in the retina and optic nerve. We induced systemic hypoxia (10% O2) in 6-8w mice for 48 h and performed in vivo imaging using optical coherence tomography (OCT) at baseline and after 48 h to analyze structural changes in the retina and optic nerve. We analyzed glial cellular and molecular changes by histology and immunofluorescence and the impact of pretreatment with 4-phenylbutyric acid (4-PBA) in oligodendroglia survival. After 48 h hypoxia, we found no change in ganglion cell complex thickness and no loss of retinal ganglion cells. Despite this, there was significantly increased expression of CCAAT-enhancer-binding protein homologous protein (CHOP), a marker of endoplasmic reticulum stress, in the retina and optic nerve. In addition, hypoxia induced obvious increase of GFAP expression in the anterior optic nerve, where it co-localized with CHOP, and significant loss of Olig2+ oligodendrocytes. Pretreatment with 4-PBA, which has been shown to reduce endoplasmic reticulum stress, rescued total Olig2+ oligodendrocytes and increased the pool of mature (CC-1+) but not of immature (PDGFRa+) oligodendrocytes. Consistent with a selective vulnerability of the retina and optic nerve in hypoxia, the most striking changes in the 48 h murine model of hypoxia were in glial cells in the optic nerve, including increased CHOP expression in the astrocytes and loss of oligodendrocytes. Our data support a model where glial dysfunction is among the earliest events in systemic hypoxia - suggesting that glia may be a novel target in treatment of hypoxia.
View details for DOI 10.1016/j.exer.2020.107957
View details for PubMedID 32032627
Nerve Growth Factor Role on Retinal Ganglion Cell Survival and Axon Regrowth: Effects of Ocular Administration in Experimental Model of Optic Nerve Injury.
Retinal ganglion cell (RGC) degeneration occurs within 2 weeks following optic nerve crush (ONC) as a consequence of reduced retro-transport of growth factors including nerve growth factor (NGF). The hypothesis that intravitreal (ivt) and eye drop (ed) administration of recombinant human NGF (rhNGF) might counteract ONC in adult rats is explored in this study. We found that both ivt- and ed-rhNGF reduced RGC loss and stimulated axonal regrowth. Chiefly, survival and regenerative effects of rhNGF were associated with a reduction of cells co-expressing Nogo-A/p75NTR at crush site borders, which contribute to glia scar formation following nerve injury, and induce further degeneration. We also found that ocular application of rhNGF reduced p75NTR and proNGF and enhanced phosphorylation of TrkA and its intracellular signals at retina level. Nogo-R and Rock2 expression was also normalized by ed-rhNGF treatment in both ONC and contralateral retina. Our findings that ocular applied NGF reaches and exerts biological actions on posterior segment of the eye give a further insight into the neurotrophin diffusion/transport through eye structures and/or their trafficking in optic nerve. In addition, the use of a highly purified NGF form in injury condition in which proNGF/p75NTR binding is favored indicates that increased availability of mature NGF restores the balance between TrkA and p75NGF, thus resulting in RGC survival and axonal growth. In conclusion, ocular applied NGF is confirmed as a good experimental paradigm to study mechanisms of neurodegeneration and regeneration, disclose biomarkers, and time windows for efficacy treatment following cell or nerve injury.
View details for DOI 10.1007/s12035-018-1154-1
View details for PubMedID 29869196
Distribution of Mesenchymal Stem Cells and Effects on Neuronal Survival and Axon Regeneration after Optic Nerve Crush and Cell Therapy
2014; 9 (10): e110722
Bone marrow-derived cells have been used in different animal models of neurological diseases. We investigated the therapeutic potential of mesenchymal stem cells (MSC) injected into the vitreous body in a model of optic nerve injury. Adult (3-5 months old) Lister Hooded rats underwent unilateral optic nerve crush followed by injection of MSC or the vehicle into the vitreous body. Before they were injected, MSC were labeled with a fluorescent dye or with superparamagnetic iron oxide nanoparticles, which allowed us to track the cells in vivo by magnetic resonance imaging. Sixteen and 28 days after injury, the survival of retinal ganglion cells was evaluated by assessing the number of Tuj1- or Brn3a-positive cells in flat-mounted retinas, and optic nerve regeneration was investigated after anterograde labeling of the optic axons with cholera toxin B conjugated to Alexa 488. Transplanted MSC remained in the vitreous body and were found in the eye for several weeks. Cell therapy significantly increased the number of Tuj1- and Brn3a-positive cells in the retina and the number of axons distal to the crush site at 16 and 28 days after optic nerve crush, although the RGC number decreased over time. MSC therapy was associated with an increase in the FGF-2 expression in the retinal ganglion cells layer, suggesting a beneficial outcome mediated by trophic factors. Interleukin-1β expression was also increased by MSC transplantation. In summary, MSC protected RGC and stimulated axon regeneration after optic nerve crush. The long period when the transplanted cells remained in the eye may account for the effect observed. However, further studies are needed to overcome eventually undesirable consequences of MSC transplantation and to potentiate the beneficial ones in order to sustain the neuroprotective effect overtime.
View details for DOI 10.1371/journal.pone.0110722
View details for Web of Science ID 000347994900027
View details for PubMedID 25347773
View details for PubMedCentralID PMC4210195
The stressed optic nerve: gliopathy in hypoxic injury and potential for therapy
ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2019
View details for Web of Science ID 000488800702167
Increased ER Stress After Experimental Ischemic Optic Neuropathy and Improved RGC and Oligodendrocyte Survival After Treatment With Chemical Chaperon.
Investigative ophthalmology & visual science
2019; 60 (6): 1953–66
Purpose: Increased endoplasmic reticulum (ER) stress is one of the earliest subcellular changes in neuro-ophthalmic diseases. In this study, we investigated the expression of key molecules in the ER stress pathways following nonarteritic anterior ischemic optic neuropathy (AION), the most common acute optic neuropathy in adults over 50, and assessed the impact of chemical chaperon 4-phenylbutyric acid (4-PBA) in vivo.Methods: We induced AION using photochemical thrombosis in adult mice and performed histologic analyses of key molecules in the ER stress pathway in the retina and optic nerve. We also assessed the effects of daily intraperitoneal injections of 4-PBA after AION.Results: In the retina at baseline, there was low proapoptotic transcriptional regulator C/EBP homologous protein (CHOP) and high prosurvival chaperon glucose-regulated protein 78 (GRP78) expression in retinal ganglion cells (RGCs). One day after AION, there was significantly increased CHOP and reduced GRP78 expressions in the ganglion cell layer. In the optic nerve at baseline, there was little CHOP and high GRP78 expression. One day after AION, there was significantly increased CHOP and no change in GRP78 expression. Treatment immediately after AION using daily intraperitoneal injection of chemical chaperone 4-PBA for 19 days significantly rescued Brn3A+ RGCs and Olig2+ optic nerve oligodendrocytes.Conclusions: We showed for the first time that acute AION resulted in increased ER stress and differential expression of ER stress markers CHOP and GRP78 in the retina and optic nerve. Rescue of RGCs and oligodendrocytes with 4-PBA provides support for ER stress reduction as possible treatment for AION.
View details for PubMedID 31060051
Stem cell therapy for treatment of ischemic optic neuropathy
ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2018
View details for Web of Science ID 000442912501176
Prevalence of IgG Autoantibodies against GD3 Ganglioside in Acute Zika Virus Infection.
Frontiers in medicine
2018; 5: 25
Zika virus (ZIKV) disease has become a global health emergency with devastating effects on public health. Recent evidences implicate the virus as an emergent neuropathological agent promoting serious pathologies of the human nervous system, that include destructive and malformation consequences such as development of ocular and fetal brain lesions, microcephaly in neonates, and Guillain-Barré syndrome (GBS) in adults. These neurological disorders of both central and peripheral nervous systems are thought to be associated to the neurotropic properties of the virus that has ability to infect neural stem cells as well as peripheral neurons, a hallmark of its pathogenicity. The presence of autoantibodies against gangliosides plays a pivotal role in the etiogenesis of GBS and a variety of neurological disorders. Gangliosides are a class of galactose-containing cerebrosides mainly expressed in nervous system tissues playing a critical role in the physiology of neural cells and neurogenesis. Herein, our findings indicate that patients at acute phase of ZIKV infection without any neurological signs show increased levels of IgG autoantibody against GD3 gangliosides, a class of glycolipid found to be highly expressed in neural stem cell acting in the maintenance of their self-renewal cellular capacity. It is possible that a pathological threshold of these antibodies is only acquired in secondary or subsequent infections. In the light of these evidences, we propose that the target of GD3 by autoimmune responses may possibly has an effect in the neuropathy and neurogenesis disorder seen during ZIKV infection.
View details for DOI 10.3389/fmed.2018.00025
View details for PubMedID 29594116
View details for PubMedCentralID PMC5854646
Time-Dependent Nerve Growth Factor Signaling Changes in the Rat Retina During Optic Nerve Crush-Induced Degeneration of Retinal Ganglion Cells
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
2017; 18 (1)
Nerve growth factor (NGF) is suggested to be neuroprotective after nerve injury; however, retinal ganglion cells (RGC) degenerate following optic-nerve crush (ONC), even in the presence of increased levels of endogenous NGF. To further investigate this apparently paradoxical condition, a time-course study was performed to evaluate the effects of unilateral ONC on NGF expression and signaling in the adult retina. Visually evoked potential and immunofluorescence staining were used to assess axonal damage and RGC loss. The levels of NGF, proNGF, p75NTR, TrkA and GFAP and the activation of several intracellular pathways were analyzed at 1, 3, 7 and 14 days after crush (dac) by ELISA/Western Blot and PathScan intracellular signaling array. The progressive RGC loss and nerve impairment featured an early and sustained activation of apoptotic pathways; and GFAP and p75NTR enhancement. In contrast, ONC-induced reduction of TrkA, and increased proNGF were observed only at 7 and 14 dac. We propose that proNGF and p75NTR contribute to exacerbate retinal degeneration by further stimulating apoptosis during the second week after injury, and thus hamper the neuroprotective effect of the endogenous NGF. These findings might aid in identifying effective treatment windows for NGF-based strategies to counteract retinal and/or optic-nerve degeneration.
View details for DOI 10.3390/ijms18010098
View details for Web of Science ID 000393030600097
View details for PubMedID 28067793
View details for PubMedCentralID PMC5297732
Bone Marrow-Derived Cells as a Therapeutic Approach to Optic Nerve Diseases
STEM CELLS INTERNATIONAL
Following optic nerve injury associated with acute or progressive diseases, retinal ganglion cells (RGCs) of adult mammals degenerate and undergo apoptosis. These diseases have limited therapeutic options, due to the low inherent capacity of RGCs to regenerate and due to the inhibitory milieu of the central nervous system. Among the numerous treatment approaches investigated to stimulate neuronal survival and axonal extension, cell transplantation emerges as a promising option. This review focuses on cell therapies with bone marrow mononuclear cells and bone marrow-derived mesenchymal stem cells, which have shown positive therapeutic effects in animal models of optic neuropathies. Different aspects of available preclinical studies are analyzed, including cell distribution, potential doses, routes of administration, and mechanisms of action. Finally, published and ongoing clinical trials are summarized.
View details for DOI 10.1155/2016/5078619
View details for Web of Science ID 000367976000001
View details for PubMedID 26649049
View details for PubMedCentralID PMC4663341
Sustained effect of bone marrow mononuclear cell therapy in axonal regeneration in a model of optic nerve crush
2014; 1587: 54–68
In adult mammals, the regeneration of the optic nerve is very limited and at the moment there are several groups trying different approaches to increase retinal ganglion cell (RGC) survival and axonal outgrowth. One promising approach is cell therapy. In previous work, we performed intravitreal transplantation of bone-marrow mononuclear cells (BMMCs) after optic nerve crush in adult rats and we demonstrated an increase in RGC survival and axon outgrowth 14 days after injury. In the present work, we investigated if these results could be sustained for a longer period of time. Optic nerve crush was performed in Lister-hooded adult rats and BMMC or saline injections were performed shortly after injury. Neuronal survival and regeneration were evaluated in rats׳ retina and optic nerve after 28 days. We demonstrated an increase of 5.2 fold in the axon outgrowth 28 days after lesion, but the BMMCs had no effect on RGC survival. In an attempt to prolong RGC survival, we established a new protocol with two BMMC injections, the second one 7 days after the injury. Untreated animals received two injections of saline. We observed that although the axonal outgrowth was still increased after the second BMMC injection, the RGC survival was not significantly different from untreated animals. These results demonstrate that BMMCs transplantation promotes neuroregeneration at least until 28 days after injury. However, the effects on RGC survival previously observed by us at 14 days were not sustained at 28 days and could not be prolonged with a second dose of BMMC.
View details for DOI 10.1016/j.brainres.2014.08.070
View details for Web of Science ID 000345180200006
View details for PubMedID 25204691
Cell Therapy Modulates Expression of Tax1-Binding Protein 1 and Synaptotagmin IV in a Model of Optic Nerve Lesion
INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE
2012; 53 (8): 4720–29
Bone marrow mononuclear cells (BMMCs) have been used with considerable success to improve regeneration and/or functional recovery in animal models of neurologic diseases. Injected into the host, they migrate to the damaged areas and release cytokines and/or trophic factors, which are capable of altering the genetic program of the injured tissue cells. In this study, there was a search for genes with altered expression in a model of optic nerve crush and cell therapy.Optic nerve crush was followed by an intravitreous injection of BMMCs or vehicle in adult rats. After 14 days, we obtained a transcriptome screening of the retinas using differential display and automatic sequencing, followed by q-PCR, Western blot, and immunohistochemistry of selected genes and proteins.Among the differentially displayed genes, transcription of the antiapoptotic Tax1-binding protein 1 (Tax1BP1) and Synaptotagmin IV (Syt IV), an immediate early gene, is increased in the treated group. Tax1BP1 expression is robust in the ganglion cell layer and is significantly increased by cell therapy. Syt IV is expressed by activated Müller cells and astrocytes in the retina and optic nerve, without changes in protein levels among the groups.Tax1BP1 and Syt IV transcription and/or expression are differently modulated by optic nerve crush and BMMC treatment, and might be related to neuronal damage and cell-therapy effects in the retina. The increased expression of Tax1BP1 in the treated eyes could be involved in the neuroprotective effects of BMMCs that were described previously by our group.
View details for DOI 10.1167/iovs.11-8198
View details for Web of Science ID 000307096400046
View details for PubMedID 22695963
Bone Marrow Mononuclear Cells Increase Retinal Ganglion Cell Survival and Axon Regeneration in the Adult Rat
2011; 20 (3): 391–406
The central nervous system (CNS) of adult mammals generally does not regenerate, and many studies have attempted to identify factors that could increase neuroprotection and/or axonal outgrowth after CNS lesions. Using the optic nerve crush of rats as a model for CNS injury, we investigated the effect of intravitreal transplantation of syngeneic bone-marrow mononuclear cells (BMMCs) on the survival of retinal ganglion cells (RGC) and on the regeneration of optic axons. Control animals received intravitreal saline injections after lesion. Injections of BMMCs resulted in a 1.6-fold increase in the number of RGCs surviving 14 days after injury. The BMMC-treated animals also had increased numbers of axons, which grew up to 1.5 mm from the crush site, and also had reduced Müller glia activation. Analysis of mRNAs in all conditions revealed an increase in levels of fibroblast growth factor 2 (FGF-2) mRNA in treated animals 14 days after injury. To investigate whether the regenerated axons could reach the brain, we retrograde labeled the RGCs by injecting a lipophilic tracer into the superior colliculus. We also analyzed the expression of NGFI-A in the superficial layers of the superior colliculus as a possible marker of synaptic input from RGC axons. We found evidence that more RGCs were able to reach the brain after treatment and we showed that NGFI-A expression was higher in the treated animals 60 days after injury. These results demonstrate that transplant of BMMCs can increase neuroprotection and neuroregeneration after injury in a model of optic nerve crush, and these effects could be mediated by FGF-2.
View details for DOI 10.3727/096368910X524764
View details for Web of Science ID 000290002400004
View details for PubMedID 20719093
TROPHIC ACTIVITY DERIVED FROM BONE MARROW MONONUCLEAR CELLS INCREASES PERIPHERAL NERVE REGENERATION BY ACTING ON BOTH NEURONAL AND GLIAL CELL POPULATIONS
2009; 159 (2): 540–49
A rat model of complete sciatic nerve transection was used to evaluate the effect of bone marrow mononuclear cells (BMMC) transplanted to the injury site immediately after lesion. Rats treated with BMMC had both sensory and motor axons reaching the distal stump earlier compared to untreated animals. In addition, BMMC transplantation reduced cell death in dorsal root ganglia (DRG) compared to control animals. Transplanted BMMC remained in the lesion site for several days but there is no evidence of BMMC differentiation into Schwann cells. However, an increase in the number of Schwann cells, satellite cells and astrocytes was observed in the treated group. Moreover, neutralizing antibodies for nerve growth factor (NGF) (but not for brain-derived neurotrophic factor and ciliary-derived neurotrophic factor) added to the BMMC-conditioned medium reduced neurite growth of sensory and sympathetic neurons in vitro, suggesting that BMMC release NGF, improve regeneration of the sciatic nerve in the adult rat and stimulate Schwann and satellite cell proliferation or a combination of both.
View details for DOI 10.1016/j.neuroscience.2008.12.059
View details for Web of Science ID 000264162300010
View details for PubMedID 19174184