Journal of experimental stroke & translational medicine最新文献

We examined the role of CCRL2 in ischemic brain injury using both in vitro and in vivo mouse stroke models. The expression of CCRL2 was enhanced at both the RNA and protein levels in cultured brain slices under ischemic conditions. Ischemia-induced cell death was reduced in brain slices derived from CCRL2 knockout (KO) mice in comparison with those from wild type (WT) mice. The infarct volume was smaller and neurological deficits were attenuated in CCRL2 KO mice when compared to WT mice subjected to a transient middle cerebral artery occlusion. Our data suggest that CCRL2 is involved in ischemia-induced brain injury in mice.

Although acute ischemic stroke has high mortality and morbidity rate but yet still has very limited treatment. In this study we have tested the concept of neuron protection by acute bioenergetic intervention or by pharmacological preconditioning with natural antioxidants. Adenosine triphosphate (ATP), pentobarbital, and suramin were encapsulated in pH-sensitive liposomes and used as bioenergy stabilizer. We induced ATP depletion model by incubating cells with media added with ATP-depleting agents for 2 hours. Treatment with bioenergy stabilizer started 10-min post inducing of ATP-depletion. The acute treatment with bioenergy stabilizer significantly increased cell viability in neuro-2a cells. In searching for a pharmacological preconditioning candidate for reducing ischemic injury, we tested cocoa-derived flavanols using bilateral common carotid artery occlusion (BCCAO). We pretreated mice with cocoa-derived flavanols (75 mg/kg) or water orally for 7 days and subjected mice for 12 minutes BCCAO. At 7 days post-ischemia, the number of surviving hippocampal CA1 neurons was significantly higher in the treated mice than in the water-treated controls. The protection from cocoa-derived flavanols was found associated with increased total antioxidant capacity in the brain. Our results indicate that for reducing acute ischemic injury bioenergetic intervention using advanced drug delivery tools is conceptually feasible, and for reducing reperfusion related secondary injury pharmacological preconditioning may provide significant protection.

Although therapeutic hypothermia and metabolic suppression have shown robust neuroprotection in experimental brain ischemia, systemic complications have limited their use in treating acute stroke patients. The core temperature and basic metabolic rate are tightly regulated and maintained in a very stable level in mammals. Simply lowering body temperature or metabolic rate is actually a brutal therapy that may cause more systemic as well as regional problems other than providing protection. These problems are commonly seen in hypothermia and barbiturate coma. The main innovative concept of this review is to propose thermogenically optimal and synergistic reduction of core temperature and metabolic rate in therapeutic hypometabothermia using novel and clinically practical approaches. When metabolism and body temperature are reduced in a systematically synergistic manner, the outcome will be maximal protection and safe recovery, which happen in natural process, such as in hibernation, daily torpor and estivation.

In the present review (part II), we discuss the challenges and promises of selective drug delivery to ischemic brain tissue by liposome technologies. In part I of this serial review, we proposed "selective drug delivery to ischemic brain tissue" as a technique for neuroprotective treatment of acute ischemic stroke. To be effective, drugs must pass a series of barriers to arrive at ischemic brain. Brain ischemia results in metabolic and structural changes in the ischemic region, which cause additional obstacles for drug delivery. Liposome drug delivery system can pass these barriers and selectively target ischemic tissue by utilizing ischemia-induced changes in metabolism and molecular structure.

The general failure of neuroprotectants in clinical trials of ischemic stroke points to the possibility of a fundamental blind spot in the current conception of ischemic brain injury, the "ischemic cascade". This is the first in a series of four papers whose purpose is to work towards a revision of the concept of brain ischemia by applying network concepts to develop a bistable model of brain ischemia. This first paper sets the stage for developing the bistable model of brain ischemia. Necessary background in network theory is introduced using examples from developmental biology which, perhaps surprisingly, can be adapted to brain ischemia with only minor modification. Then, to move towards a network model, we extract two core generalizations about brain ischemia from the mass of empirical data. First, we conclude that all changes induced in the brain by ischemia can be classified as either damage mechanisms that contribute to cell death, or stress responses that contribute to cell survival. Second, we move towards formalizing the idea of the "amount of ischemia", I, as a continuous, nonnegative, monotonically increasing quantity. These two generalizations are necessary precursors to reformulating brain ischemia as a bistable network.

The general failure of neuroprotectants in clinical trials of ischemic stroke points to the possibility of a fundamental blind spot in the current conception of ischemic brain injury, the "ischemic cascade". This is the fourth in a series of four papers whose purpose is to work towards a revision of the concept of brain ischemia by applying network concepts to develop a bistable model of brain ischemia. Here we consider additional issues to round out and close out this initial presentation of the bistable network view of brain ischemia. Initial considerations of the network architecture underlying the post-ischemic state space are discussed. Network and differential equation models of brain ischemia are compared. We offer a first look at applying the bistable model to focal cerebral ischemia. The limitations of the present formulation of the bistable model are discussed. This work concludes with a series of questions by which to direct future efforts.

In order to evaluate novel stroke therapies, it is essential to utilize a highly reproducible model of focal cerebral ischemia. Though a range of rodent stroke models has been employed in the literature, there are persistent issues regarding reproducibility of the ischemic zone, as there is considerable inter-animal and inter-laboratory variation. We have developed a highly reproducible model of stroke that involves direct electrocoagulation of the MCA in SCID (CB-17/lcr-scid/scidJcl) and CB-17 (CB-17/lcr-+/+Jcl) mice. Using a modification of the Tamura method, our results demonstrate reproducible cortical infarction with high survival in the chronic period (up to 180 days) in SCID and CB-17, but not in C57BL/6, mice. We believe that our preclinical model represents a step forward for testing future therapeutic methods potentially applicable to patients with stroke.