Martin R. Farlow

IFATS Collection: The Conditioned Media of Adipose Stromal Cells Protect Against Hypoxia‐Ischemia‐Induced Brain Damage in Neonatal Rats

Adipose tissue stroma contains a population of mesenchymal stem cells, which support repair when administered to damaged tissues, in large part through secreted trophic factors. We directly tested the ability of media collected from cultured adipose‐derived stem cells (ASCs) to protect neurons in a rat model of brain hypoxic‐ischemic (HI) injury. Concentrated conditioned medium from cultured rat ASCs (ASC‐CM) or control medium was infused through the jugular vein of neonatal Sprague‐Dawley rats subjected to HI injury. The ASC‐CM was administered either 1 hour before or 24 hours after induction of injury. Analysis at 1 week indicated that administration at both time points significantly protected against hippocampal and cortical volume loss. Analysis of parallel groups for behavioral and learning changes at 2 months postischemia demonstrated that both treated groups performed significantly better than the controls in Morris water maze functional tests. Subsequent post‐mortem evaluation of brain damage at the 2‐month time point confirmed neuronal loss to be similar to that observed at 1 week for all groups. We have identified several neurotrophic factors in ASC‐CM, particularly insulin‐like growth factor‐1 and brain‐derived neurotrophic factor, which are important factors that could contribute to the protective effects of ASCs observed in studies with both in vitro and in vivo neuronal injury models. These data suggest that delivery of the milieu of factors secreted by ASCs may be a viable therapeutic option for treatment of HI, as well as other brain injuries. STEM CELLS 2009;27:478–488

Preclinical trials in autosomal dominant AD: Implementation of the DIAN-TU trial

The Dominantly Inherited Alzheimers Network Trials Unit (DIAN-TU) was formed to direct the design and management of interventional therapeutic trials of international DIAN and autosomal dominant Alzheimers disease (ADAD) participants. The goal of the DIAN-TU is to implement safe trials that have the highest likelihood of success while advancing scientific understanding of these diseases and clinical effects of proposed therapies. The DIAN-TU has launched a trial design that leverages the existing infrastructure of the ongoing DIAN observational study, takes advantage of a variety of drug targets, incorporates the latest results of biomarker and cognitive data collected during the observational study, and implements biomarkers measuring Alzheimers disease (AD) biological processes to improve the efficiency of trial design. The DIAN-TU trial design is unique due to the sophisticated design of multiple drugs, multiple pharmaceutical partners, academics servings as sponsor, geographic distribution of a rare population and intensive safety and biomarker assessments. The implementation of the operational aspects such as home health research delivery, safety magnetic resonance imagings (MRIs) at remote locations, monitoring clinical and cognitive measures, and regulatory management involving multiple pharmaceutical sponsors of the complex DIAN-TU trial are described.

Temporoparietal Hypometabolism in Frontotemporal Lobar Degeneration and Associated Imaging Diagnostic Errors

OBJECTIVEnTo evaluate the cause of diagnostic errors in the visual interpretation of positron emission tomographic scans with fludeoxyglucose F 18 (FDG-PET) in patients with frontotemporal lobar degeneration (FTLD) and patients with Alzheimer disease (AD).nnnDESIGNnTwelve trained raters unaware of clinical and autopsy information independently reviewed FDG-PET scans and provided their diagnostic impression and confidence of either FTLD or AD. Six of these raters also recorded whether metabolism appeared normal or abnormal in 5 predefined brain regions in each hemisphere-frontal cortex, anterior cingulate cortex, anterior temporal cortex, temporoparietal cortex, and posterior cingulate cortex. Results were compared with neuropathological diagnoses.nnnSETTINGnAcademic medical centers.nnnPATIENTSnForty-five patients with pathologically confirmed FTLD (n=14) or AD (n=31).nnnRESULTSnRaters had a high degree of diagnostic accuracy in the interpretation of FDG-PET scans; however, raters consistently found some scans more difficult to interpret than others. Unanimity of diagnosis among the raters was more frequent in patients with AD (27 of 31 patients [87%]) than in patients with FTLD (7 of 14 patients [50%]) (P=.02). Disagreements in interpretation of scans in patients with FTLD largely occurred when there was temporoparietal hypometabolism, which was present in 7 of the 14 FTLD scans and 6 of the 7 scans lacking unanimity. Hypometabolism of anterior cingulate and anterior temporal regions had higher specificities and positive likelihood ratios for FTLD than temporoparietal hypometabolism had for AD.nnnCONCLUSIONSnTemporoparietal hypometabolism in FTLD is common and may cause inaccurate interpretation of FDG-PET scans. An interpretation paradigm that focuses on the absence of hypometabolism in regions typically affected in AD before considering FTLD is likely to misclassify a significant portion of FTLD scans. Anterior cingulate and/or anterior temporal hypometabolism indicates a high likelihood of FTLD, even when temporoparietal hypometabolism is present. Ultimately, the accurate interpretation of FDG-PET scans in patients with dementia cannot rest on the presence or absence of a single region of hypometabolism but rather must take into account the relative hypometabolism of all brain regions.

Association of statin use with cognitive decline in elderly African Americans

Background: Previously reported associations between statin use and incident dementia or cognitive decline have been inconsistent. We report the results from a 3-year prospective study on the association of statin use on cognitive decline and incident dementia in elderly African Americans. Methods: A community-based cohort of 1,146 African Americans aged 70 and older living in Indianapolis, Indiana, was evaluated in 2001 and 2004. The instrument used for cognitive assessment was the Community Screening Interview for Dementia (CSI-D). Cognitive decline was defined as CSI-D scores measured at 2001 minus scores at 2004. Measurements of low-density lipoprotein cholesterol (LDL-C) and C-reactive protein (CRP) were obtained from baseline blood samples. Results: Adjusting for age at baseline, gender, education, and the possession of ApoE ε4 allele, baseline statin use was associated with less cognitive decline (p = 0.0177). There were no significant interactions of statin use when LDL-C and CRP were included. Logistic regression with the four independent variables showed that statin use may be associated with a reduction in incident dementia (OR = 0.32; p = 0.0673). Association with cognitive decline was less clear when investigating statin use over time. Significance remained only for those who discontinued prior to follow-up compared to continuous users or users who started after baseline. Conclusions: The relationship between statin use and cognitive decline is complex and subjected to unknown confounders. This effect may not be associated with the cholesterol lowering or anti-inflammatory action of statins. GLOSSARY: AD = Alzheimer disease; ANCOVA = analysis of covariance; BMI = body mass index; CAMDEX = Cambridge Examination for Mental Disorders of the Elderly informant interview; CERAD = Consortium to Establish a Registry for Alzheimer’s Disease; CHIF = Clinician Home-based Interview to assess Function; CRP = C-reactive protein; CSI-D = Community Screening Instrument for Dementia; HDL = high-density lipoprotein; HMG-CoA = 3-hydroxy-3-methylglutaryl-coenzyme A; LDL-C = low-density lipoprotein cholesterol; LLAs = lipid-lowering agents; NSAIDs = nonsteroidal anti-inflammatory drugs.

Foci of increased T2 signal intensity in MR images of healthy elderly subjects. A follow-up study.

An 18‐month follow‐up study was conducted on 26 healthy elderly subjects with and without foci of increased T2 signal intensity on MR imaging. The subjects did not differ with respect to health status or cognitive performance as measured by the Cognitive Subscale of the Cambridge Mental Disorders of the Elderly Examination and the Mini Mental State Examination at follow‐up. There was a significant decline in performance on the Digit Symbol Substitution Test in subjects who had evidence of T2 foci compared to the performance of subjects without T2 foci. This may indicate that the presence of T2 foci is correlated with subtle difficulties in learning and memory.

Rivastigmine: an open-label, observational study of safety and effectiveness in treating patients with Alzheimer's disease for up to 5 years

BackgroundRivastigmine, a butyl- and acetylcholinesterase inhibitor, is approved for symptomatic treatment of Alzheimers disease (AD). Data supporting the safety and efficacy of second-generation cholinesterase inhibitors, such as rivastigmine, are available for treatment up to 1 year, with limited data up to 2 1/2 years. The purpose of this report is to present safety and effectiveness data for rivastigmine therapy in patients with mild to moderately severe AD receiving treatment for up to 5 years.MethodsAn observational approach was used to study 37 patients with originally mild to moderate AD receiving rivastigmine as a therapy for AD in an open-label extension (ENA713, B352 Study Group, 1998).ResultsThe initial trial demonstrated rivastigmine was well-tolerated and effective in terms of cognition, global functioning and activities of daily living. In this open label extension, high-dose rivastigmine therapy was safe and well tolerated over a 5-year period. Two thirds of the participants still enrolled at week 234 were in the original high-dose rivastigmine group during the double-blind phase, suggesting that early therapy may confer some benefit in delaying long-term progression of symptoms.ConclusionsLong-term cholinesterase inhibition therapy with rivastigmine was well tolerated, with no dropouts due to adverse effects past the initial titration period. Early initiation of treatment, with titration to high-dose therapy, may have an advantage in delaying progression of the illness.

The DIAN-TU Next Generation Alzheimer's prevention trial: Adaptive design and disease progression model

The Dominantly Inherited Alzheimer Network Trials Unit (DIAN‐TU) trial is an adaptive platform trial testing multiple drugs to slow or prevent the progression of Alzheimers disease in autosomal dominant Alzheimers disease (ADAD) families. With completion of enrollment of the first two drug arms, the DIAN‐TU now plans to add new drugs to the platform, designated as the Next Generation (NexGen) prevention trial.

Correlation of clinical features with argyrophilic grains at autopsy

Argyrophilic grains (AGs) are a pathologic feature found in association with neurodegenerative disease. Some have suggested that these features may occur as a distinctive condition. We reviewed 80 subjects from our tissue bank with pathologically confirmed AGs and identified their clinical features. We compared these subjects features to the features of subjects with matched clinical diagnoses but without AGs. Subjects with AGs represented 21.7% of the entire autopsy sample from 1999 to 2005 (80 out of 367). Of Alzheimer disease (AD) subjects, 43 out of 233 had AGs (18.4% of AD subjects); 11 out of 42 Parkinson disease with dementia subjects had AGs (26.1% of Parkinson disease with dementia subjects); 2 out of 9 dementia with Lewy bodies subjects had AGs (22.2% of dementia with Lewy bodies subjects); 4 out of 15 mild cognitive impairment subjects had AGs (26.7% of mild cognitive impairment subjects); and 20 out of 68 cognitively normal subjects had AGs (29.4% of cognitively normal). Subjects with AGs tended to be older but only significantly so in AD. Many comorbid non-neurologic health conditions were seen in cases of AGs without any single predilection emerging. AGs occur in approximately 22% of the entire autopsy cohort and are likely associated with advanced age. No distinctive antemortem clinical features were over represented in the AG cases. AGs can occur with or without neurodegenerative conditions and can occur in the absence of significant cognitive decline. AGs are not clearly associated with any single comorbid health condition.

Increased β-amyloid deposition in Tg-SWDI transgenic mouse brain following in vivo lead exposure.

Previous studies in humans and animals have suggested a possible association between lead (Pb) exposure and the etiology of Alzheimers disease (AD). Animals acutely exposed to Pb display an over-expressed amyloid precursor protein (APP) and the ensuing accumulation of beta-amyloid (Aβ) in brain extracellular spaces. This study was designed to examine whether in vivo Pb exposure increased brain concentrations of Aβ, resulting in amyloid plaque deposition in brain tissues. Human Tg-SWDI APP transgenic mice, which genetically over-express amyloid plaques at age of 2-3 months, received oral gavages of 50mg/kg Pb acetate once daily for 6 weeks; a control group of the same mouse strain received the same molar concentration of Na acetate. ELISA results revealed a significant increase of Aβ in the CSF, brain cortex and hippocampus. Immunohistochemistry displayed a detectable increase of amyloid plaques in brains of Pb-exposed animals. Neurobehavioral test using Morris water maze showed an impaired spatial learning ability in Pb-treated mice, but not in C57BL/6 wild type mice with the same age. In vitro studies further uncovered that Pb facilitated Aβ fibril formation. Moreover, the synchrotron X-ray fluorescent studies demonstrated a high level of Pb present in amyloid plaques in mice exposed to Pb in vivo. Taken together, these data indicate that Pb exposure with ensuing elevated Aβ level in mouse brains appears to be associated with the amyloid plaques formation. Pb apparently facilitates Aβ fibril formation and participates in deposition of amyloid plaques.

AMP-ACTIVATED KINASE MEDIATES ADIPOSE STEM CELL-STIMULATED NEURITOGENESIS OF PC12 CELLS

Adipose tissue stroma contains a population of mesenchymal stem cells, which support repair of damaged tissues through the protective effects of secreted trophic factors. Neurotrophic factors, including nerve growth factor (NGF) have been identified in media collected from cultured adipose-derived stem cells (ASC). We previously demonstrated that administration of cell-free ASC conditioned medium (ASC-CM) at 24 h after injury reduced lesion volume and promoted functional recovery in a rat model of neonatal brain hypoxic-ischemic (HI) injury. The timing of administration well after the peak in neural cell apoptosis in the affected region suggests that regeneration of lost neurons is promoted by factors in ASC-CM. In this study, we determined which of the factors in ASC-CM could induce neurogenesis by testing the ability of the mixture, either whole or after inactivating specific components, to stimulate neurite outgrowth in vitro using the neurogenic cell line PC12. Neuritogenesis in PC12 cells treated with ASC-CM was observed at a level comparable to that observed with purified recombinant NGF. It was observed that NGF in ASC-CM was mainly responsible for inducing PC12 cell neuritogenesis. Interestingly, both ASC-CM and NGF induced PC12 cell neuritogenesis through activation of the AMP-activated kinase (AMPK) pathway which is the central protein involved in controlling many critical functions in response to changes in the cellular energy status. Pharmacological and genetic inhibition of AMPK activity greatly reduced neuritogenesis in PC12 cells. These results suggest that, in addition to possessing neuroprotective properties, ASC-CM mediates repair of damaged tissues through inducing neuronal differentiation via NGF-induced AMPK activation.