Abstract5-Lipoxygenase (5LO), by producing leukotrienes, is a proinflammatory enzyme, and there is evidence suggesting that it is up-regulated with aging and may be involved in Alzheimer's disease (AD). In this paper, we studied the effect of 5LO-targeted gene disruption on the amyloid phenotype of a transgenic mouse model of AD, the Tg2576. Amyloid-β (Aβ) deposition in the brains of Tg2576 mice lacking 5LO was reduced by 64-80% compared with Tg2576 controls. This reduction was associated with a similar significant decrease in Aβ levels measured by sandwich ELISA. Absence of 5LO did not induce any significant change in amyloid-β precursor protein (APP) levels and processing, or Aβ catabolic pathways. Furthermore, in vitro studies showed that 5LO activation or 5LO metabolites increase, whereas 5LO inhibition decreases, Aβ formation, secondary to correspondent changes in γ-secretase activity. These data establish for the first time a novel functional role for 5LO in the pathogenesis of AD-like amyloidosis, thereby modulating γ-secretase activity. Our work suggests that pharmacological inhibition of 5LO could provide a novel therapeutic tool for AD. Keywordsγ-secretase; Tg2576; Aβ; amyloid-β precursor protein; leukotrienes Alzheimer's disease (AD) is a neurodegenerative disorder that causes progressive loss of cognitive function and dementia. The pathological hallmarks in the AD brains are amyloid plaques in the extracellular parenchyma consisting mainly of Amyloid-β (Aβ) peptides (1), and intraneuronal tangles made of abnormally phosphorylated microtubule-associated tau protein (2).Increasing evidence from human and mouse models suggests that inflammation is an important player in the pathogenesis of AD (3). Eicosanoids, including prostaglandins and leukotrienes, derive from arachidonic acid by the action of cyclooxygenase (COX-1 and COX-2), lipoxygenase (12/15 lipoxygenase (12/15LO), and 5-lipoxygenase (5LO) enzymes. They have important proinflammatory functions and a large array of other biological activities (4). The roles of cyclooxygenases (5-8) and 12/15LO (9,10) in AD have been studied, but much less attention has been directed to the 5LO (11). Previously, it has been shown that 5LO is present in the central nervous system (CNS) in neurons and other cell types in mice (12) and rats (13,14). 5LO and leukotrienes in the CNS have neuromodulatory and neuroendocrine functions (14-16) and might play an important role in aging-associated neurodegenerative diseases (12,13). 5LO and its metabolites have been also been reported to be associated with excitotoxic injury (17,18) and cerebral ischemia (19). Taken together, these data would indirectly indicate that 5LO may have also a role in neurodegeneration, but only few studies have directly addressed this issue. It has been shown that 5LO promoter mutations cause a lower 5LO expression compared to wild-type (20). In a pilot study on the association of 5LO promoter polymorphism and the age of onset of AD, a trend toward higher frequency of wild-type 5LO promoter was f...

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Although hepatic cell transplantation (CT) holds the promise of bridging patients with end-stage chronic liver failure to whole liver transplantation, suitable cell populations are under debate. In addition to hepatic cells, mesenchymal stem cells (MSCs) and hematopoietic stem cells (HSCs) are being considered as alternative cell sources for initial clinical cell work. Fetal liver (FL) tissue contains potential progenitors for all these cell lineages. Based on the collagenase incubation of tissue fragments, traditional isolation techniques yield only a fraction of the number of available cells. We report a 5-step method in which a portal vein in situ perfusion technique is used for tissue from the late second trimester. This method results in the high viabilities known for adult liver vascular perfusion, addresses the low cell yields of conventional digestion methods, and reduces the exposure of the tissue to collagenase 4-fold. We used donated tissue from gestational weeks 18 to 22, Additional Supporting Information may be found in the online version of this article.