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Benowitz L.I.,Laboratories for Neuroscience Research in Neurosurgery | Yin Y.,Harvard University
Archives of Ophthalmology | Year: 2010

Retinal ganglion cells are usually not able to regenerate their axons after optic nerve injury or degenerative disorders, resulting in lifelong visual loss. This situation can be partially reversed by activating the intrinsic growth state of retinal ganglion cells, maintaining their viability, and counteracting inhibitory signals in the extracellular environment. Advances during the past few years continue to extend the amount of regeneration that can be achieved in animal models. These findings give hope that clinically meaningful regeneration may become a reality within a few years if regenerating axons can be guided to their appropriate destinations. ©2010 American Medical Association. All rights reserved. Source

Andereggen L.,University of Bern | Andereggen L.,Laboratories for Neuroscience Research in Neurosurgery | Andereggen L.,Harvard University | Neuschmelting V.,University of Bern | And 5 more authors.
BioMed Research International | Year: 2014

Background. Microvascular dysfunction and microthrombi formation are believed to contribute to development of early brain injury (EBI) after aneurysmal subarachnoid hemorrhage (SAH). Objective. This study aimed to determine (i) extent of microthrombus formation and neuronal apoptosis in the brain parenchyma using a blood shunt SAH model in rabbits; (ii) correlation of structural changes in microvessels with EBI characteristics. Methods. Acute SAH was induced using a rabbit shunt cisterna magna model. Extent of microthrombosis was detected 24 h post-SAH (n = 8) by fibrinogen immunostaining, compared to controls (n = 4). We assessed apoptosis by terminal deoxynucleotidyl transferase nick end labeling (TUNEL) in cortex and hippocampus. Results. Our results showed significantly more TUNEL-positive cells (SAH: 115 ± 13; controls: 58 ± 10; P = 0.016) and fibrinogen-positive microthromboemboli (SAH: 9 ± 2; controls: 2 ± 1; P = 0.03) in the hippocampus after aneurysmal SAH. Conclusions. We found clear evidence of early microclot formation in a rabbit model of acute SAH. The extent of microthrombosis did not correlate with early apoptosis or CPP depletion after SAH; however, the total number of TUNEL positive cells in the cortex and the hippocampus significantly correlated with mean CPP reduction during the phase of maximum depletion after SAH induction. Both microthrombosis and neuronal apoptosis may contribute to EBI and subsequent DCI. © 2014 Lukas Andereggen et al. Source

Andereggen L.,Laboratories for Neuroscience Research in Neurosurgery | Andereggen L.,Harvard University | Andereggen L.,University of Bern | Neuschmelting V.,University of Bern | And 7 more authors.
Journal of Visualized Experiments | Year: 2014

Early brain injury and delayed cerebral vasospasm both contribute to unfavorable outcomes after subarachnoid hemorrhage (SAH). Reproducible and controllable animal models that simulate both conditions are presently uncommon. Therefore, new models are needed in order to mimic human pathophysiological conditions resulting from SAH. This report describes the technical nuances of a rabbit blood-shunt SAH model that enables control of intracerebral pressure (ICP). An extracorporeal shunt is placed between the arterial system and the subarachnoid space, which enables examiner-independent SAH in a closed cranium. Step-by-step procedural instructions and necessary equipment are described, as well as technical considerations to produce the model with minimal mortality and morbidity. Important details required for successful surgical creation of this robust, simple and consistent ICP-controlled SAH rabbit model are described. © JoVE 2006-2014. All Rights Reserved. Source

Koriyama Y.,Kanazawa University | Koriyama Y.,Harvard University | Kurimoto T.,Laboratories for Neuroscience Research in Neurosurgery | Kurimoto T.,Osaka Medical College | And 5 more authors.
Brain and Nerve | Year: 2014

The optic nerve has been widely studied in search for insights into mechanisms that suppress or promote axon regeneration after injury. Like other CNS neurons, adult retinal ganglion cells (RGCs) normally fail to regenerate their axons after optic nerve injury. Recent studies have identified molecular pathways able to allow partial regeneration of damaged RGCs axons in mature rodents; however, it is still unknown, whether regrowing optic axons can re-enter the brain in large numbers, innervate the correct target areas, and thus restore vision. We investigated these questions by using three manipulations that synergistically increase regeneration far above the level induced by any of the three used alone. Oncomodulin is a calcium-binding protein secreted by activated macrophages and neutrophils and stimulates RGCs to regenerate axons. Its ability to bind to RGCs and activate a downstream response is enhanced by elevating intracellular cAMP. Studies were carried out in mice with a conditional deletion of the gene encoding PTEN, a phosphatase and tensin homolog that suppresses signaling through the Akt/mTOR/S6K pathway. Our results showed that intraocular inflammation, deletion of the PTEN gene and elevation of intracellular cAMP exert synergistic effects that enable RGCs to regenerate the full length of axons, form synapses, and restore simple visual functions. These results demonstrate the feasibility of reconstructing central circuitry for vision after optic nerve damage in mature mammals. Source

de Lima S.,Laboratories for Neuroscience Research in Neurosurgery | de Lima S.,Harvard University | de Lima S.,Federal University of Rio de Janeiro | Habboub G.,Laboratories for Neuroscience Research in Neurosurgery | And 3 more authors.
International Review of Neurobiology | Year: 2012

The optic nerve has been widely studied for insights into mechanisms that suppress or promote axon regeneration after central nervous system injury. Following optic nerve damage in adult mammals, retinal ganglion cells (RGCs) normally fail to regenerate their axons, resulting in blindness in patients who suffer from neurodegenerative diseases such as glaucoma or who have sustained traumatic injury to the optic nerve. Over the past several decades, many groups have investigated the basis of regenerative failure in the hope of developing strategies to stimulate the regrowth of axons and restore visual function. New findings show that a combination of therapies that act synergistically to activate RGCs' intrinsic growth state enables these cells to regenerate their axons the full length of the optic nerve, across the optic chiasm, and into the brain, where they establish synapses in appropriate target zones and restore limited visual responses. These treatments involve the induction of a limited inflammatory response in the eye to increase levels of oncomodulin and other growth factors; elevation of intracellular cAMP; and deletion of the pten gene in RGCs. Although these methods cannot be applied in the clinic, they point to strategies that might be. © 2012 Elsevier Inc. Source

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