New Faculty I
The applicant proposes to undertake a program of research that aims to reveal how Alzheimer’s disease (AD) brain affects the biology of neural progenitor cells. This aim is to understand if neurogenesis in AD is dysfunctional and leads to a vulnerable environment for later occurring neurodegeneration. It will also investigate systemically what mechanisms are altered in the AD neural progenitors that will generate potential drug targets. Using a broad molecular approach to the study of NPC biology in AD-like environment, the candidate plans to answer two crucial and interrelated questions: first, how and why neurogenesis is altered in the AD brain and second, does adult neurogenesis contributes to the development of AD and related dementias. The study is built on the candidate’s expertise in neural stem cell biology, functional neurogenomics and animal experimentation. This is a highly integrative approach that takes advantage of vast resources in LA BioMed and the neighboring UCLA Westwood campus. Two experts in the neural stem cell biology are involved as mentors and co-investigators, Dr. Harley Kornblum and Dr. Michael Sofroniew. Therefore, the chances for success are high. The project approaches a new and highly attractive area of investigation and the results will have direct impact on the design of future neuroreplacement therapies for AD and other neurological diseases.
Statement of Benefit to California:
It is estimated that the costs for Alzheimer’s disease (AD) patients in California will increase 83.5 percent in the period 2000 ($26 billion) to 2020 ($47.5 billion) and will grow another 60% from 2020 to 2040 ($75.5 billion). Total costs of caring for AD patients will nearly triple between 2000 and 2040 (Fox et al, 2001). The rapid aging of the U.S. population and Californians in particular makes it necessary to aggressively invest in the development of novel therapies reducing societal burden of Alzheimer's disease in the nearest future. A major challenge not addressed by existing therapeutic interventions for AD is the regeneration of lost neurons and neural circuitry to restore cognitive function. In the light of the above, stem cell based cell replacement therapies look particularly attractive and indeed this approach could revolutionize the whole field. However, mounting evidence indicates neurogenesis might be altered in AD brain raising the question of how feasible such approach would be if the AD environment proves to be toxic for newly introduced neural progenitor cells. This proposal aims to establish and understand the relationship between AD and functional neurogenesis allowing us to predict the possible outcomes of the stem cell therapy and manipulate the AD brain environment for more efficient cell replacement strategies. This work will also establish the link between existing and active functional adult neurogenesis (ANG) and neurodegeneration. The contribution of ANG in AD is not clear and needs to be investigated. By deciphering the mechanisms of ANG in AD brain, we might be able to manipulate endogenous neural progenitors, or control the fate of transplanted neural progenitors towards more efficient cell replacement for AD and other various neurological diseases. Therefore, the information obtained from this work will be fundamental for the design of future neuroreplacement therapies and will benefit the state of California directly.
SYNOPSIS: This proposal aims to understand the relationship between an Alzheimer’s disease (AD) -like pathological environment and functional neurogenesis in order to clarify the disease's pathogenesis and to facilitate cell replacement therapies in AD. Recent studies suggest that there are abnormalities in neurogenesis in AD including a recent investigation demonstrating that environmental "enrichment" of an AD mutant mouse led to a delay in neuropathological abnormalities. The reason for the effect of enrichment may relate to neurogenesis. The applicant hypothesizes that there is a relationship between early development and late onset neurodegeneration which involves neural proliferation and cell fate decisions and that dysfunctional adult neurogenesis facilitates the development of AD. The applicant proposes to use a battery of mouse models of AD to investigate the integrity of neurogenesis at early and late stages of development. STRENGTHS AND WEAKNESSES OF THE RESEARCH PLAN: The PI proposes three specific aims. In the first specific aim, the PI will investigate the effect of AD on the function of neural progenitor cells (NPCs). The hypothesis being tested is that the AD-like environment affects aspects of embryonic and adult NPC proliferation and differentiation. The PI will explore NPC proliferation and differentiation in control and mutant mouse models of AD using BrdU and immunolabeling. Using neurosphere cultures, the PI will explore the effects of the AD environment on NPCs isolated from control and AD mutant mice from embryonic stages through maturity. Cell proliferation, differentiation and maturity will be evaluated by immunocytochemistry and clonal analysis. The PI presents rather striking preliminary dta showing a decrease in BrdU incorporation in vivo and a decrease in size and number of neurospheres from TAUP301L mice. The hypothesis underlying specific aim 2 is that there are specific regulatory pathways activated in adult progenitors in response to the AD-like environment and that neurodegenerative processes affect regulatory pathways in the NPCs of the AD mice. In this specific aim, the PI will cross the AD mutant mice with GFAP-GFP mice, and hippocampal NPCs will be obtained during early, mid and late stages of life (before, during a late disease stage) and analyzed by microarray and transcription profiling. Genes of interest will be further investigated by immunolabeling, in situ hybridization and RT-PCR. These investigations will clearly yield a large amount of data that may be difficult to analyze. One potential shortcoming identified by the PI is that post-transciptional changes important in AD-induced perturbations in neurogenesis will not be assessed. The reviewers noted the PI is very experienced with these techniques and at least one reviewer described the PI as “expert at microarray” but further noted that one of the PI’s mentors characterized him as simply not an “informatics guy.” At least one reviewer regarded this aim as a potential fishing trip. In the third specific aim 3, adult neurogenesis (ANG) in AD mouse models will be ablated by hippocampal x-irradiation and a genetic approach using GFAP-thymidine kinase mice to determine the effect at the molecular, histological and behavioral level - testing the hypothesis that ANG ablation facilitates the development of AD. These studies are of interest in view of recent data suggesting that "enrichment" leads to delayed pathology of AD mutant mice. The reviewers regarded these as interesting experiments because they highlight the effect of ANG on AD and because they focus on early embryonic events as being important in the pathogenesis of neurodegenerative diseases. However, a reviewer was concerned that the applicant did not cite or was unaware of relevant publications in prominent journal(s) in this area of research including a study on endogeneous stem cell differentiation in APP transgenic mice that utilized labeling with BrdU and immunostaining with cell specific markers as well as studies in mutant mice indicating that the mutant environment modulated the differentiation of transplanted neural stem cells. A reviewer also noted that there are no AD mice, rather that the AD mouse models described in the proposal are transgenic mice carrying a human mutant gene found in familial AD, which may only represent certain aspect of AD pathologies. From this reviewer’s point of view, more targeted mechanistic studies to investigate the effect of each pathological change in AD on the stem cells may be desired rather than in vivo studies. Overall the reviewers found the proposal interesting. It describes a huge amount of work that will undoubtedly generate a massive amount of data. There was some concern that the proposed microarray studies were a ‘fishing expedition’. The technical expertise of the applicant was acknowledged. Some of the reviewers believed that this expertise in conjunction with the preliminary data suggest the feasibility of obtaining new useful information that could provide insights into the relationship of stem cells to AD and its potential for treatment. QUALIFICATIONS AND POTENTIAL OF THE PRINCIPAL INVESTIGATOR: Dr. Karsten appears to be an industrious person with creative ideas. Dr. Karsten has an excellent background and training to carry out this proposal. In particular, his position in D. Geschwind’s lab for 7 years and his current association with H. Kornblum and M. Sofroniew has strengthened his background. Dr. Karsten obtained his PhD in Uppsala University in Sweden. He was a post-doctoral fellow from 2000-2003 in the Department of Neurology and then an Assistant Professional Research Scientist in the same Department until 2007. These activities were in the lab of Daniel Geschwind. Dr. Karsten started a tenure track appointment in Neurology at Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center where he is Investigator and Chief of the Division of Neuroscience there. This proposal involves a collaboration with Dr. Sofroniew, Professor of Neurobiology at UCLA and Dr. Kornblum who is the director of the UCLA Stem Cell Center, so that access to the core facilities in Westwood campus is assured. Dr. Kornblum notes that he will serve as a primary mentor to Dr. Karsten. Dr. Sofroniew has also stated that he will be a mentor to the applicant. While the number of his publications is not huge, since 2005, he has published in Cell, Neuron and Nature Neuroscience. He lists 21 publications with 4 first authored refereed papers since 2000 including a paper in Developmental Biology in 2003 on microarray analysis of NPCs, and a paper in Neuron in 2006 describing a genomic screen for modifiers of tauopathy. Many of his publications involve microarray studies, and Dr. Kornblum notes that he "has excellent insight into how one approaches array data." Dr. Karsten is a collaborator (25% effort) on an NIH grant entitled "In vivo studies of the epileptic hippocampus" that started in 2003 and ends 11/07 and co-PI (10% effort) on a one year NIH grant entitled "Comparative Genomics of Motor Neuron Vulnerability." Dr. Karsten is also co-PI on a grant from the Pape Adams Charitable Foundation and PI on a grant for the ALS Association related to gene expression in ALS. The reviewers were concerned about the scientific environment at Harbor General Hospital with respect to neuroscience and SCs. In addition, details related to mentoring of Dr. Karsten and guidance related to the preparation for tenure were not provided. Furthermore, there was concern that neither the PI nor the two mentors had strong expertise in AD. These issues raised concerns for the career development of Dr. Karsten in AD stem cell therapy and about the likelihood that he would become a leader in the SC field. INSTITUTIONAL COMMITMENT TO PRINCIPAL INVESTIGATOR: The letter of commitment in this application from the Chair of Neurology at Harbor-UCLA Medical Center and the President and CEO of LA BioMed describes the facilities. These include FACS, confocal microscopes, and animal facility. The letter does state that LA BioMed is "deeply committed to promoting stem cell research on campus," and the Board of Directors approved the Stem Cell Research Seed Grant Program providing funds for investigators to pursue stem cell research projects on campus. In addition, there is a Stem Cell Research Advisory Committee. Note was made that "we are actively recruiting young investigators to the campus, including some whose interests lie in the field of stem cell research," but no further details about this are provided. No mention of guidance of the candidate with respect to a preparation for tenure or its likelihood was given. No details about the extent of scholarly pursuit among faculty at this Institute was detailed. One reviewer noted that it seemed as if the applicant will have to stand alone at present in this institution as the “stem-cell scientist.” In many ways, the letter from Dr. Kornblum, Dr. Karsten's collaborator at UCLA who will also be his formal mentor was a much stronger letter. These aspects of the proposal raise concerns that Harbor-UCLA Medical Center will not be an optimal environment for fostering Dr. Kornblum's career, and lowered the reviewers’ enthusiasm. DISCUSSION: The strengths of this proposal include uniform interest by the reviewers in the research focus on the impact of an Alzheimer’s disease-like environment on embryonic and adult neurogenesis and agreement that the PI was a creative and industrious investigator who was well trained and is an expert in microarray. The main weaknesses of the proposal were concerns about the institutional commitment to providing a strong scientific environment for stem cell research and for providing guidance for obtaining tenure. There was some concern that Dr. Karsten was a “lone wolf”. The reviewers noted collaboration with and mentoring from Drs. Kornblum and Sofroniew at neighboring UCLA but also noted that details on the mentoring was lacking. There was some concern that neither Dr. Karsten nor his collaborators had a strong background in the AD field and that the PI does not seem to have acquired adequate knowledge of the field, as he does not cite important, relevant publications.