Public Abstract There is great promise in the use of human embryonic stem cells to treat neurodegenerative disorders. However, there are several obstacles that need to be overcome before this replacement therapy can become a reality to treat humans. The proposed research is intended to address some of the fundamental principles underlying migration of human embryonic stem cells into regions of the brain that are most vulnerable to neurodegenerative disorders, such as Alzheimer’s disease. Specifically, we intend to take advantage of an intrinsic migratory route for newborn neurons in the adult rodent brain. Our recent studies have shown that newborn neurons arise in the wall of the lateral ventricle and migrate caudally in the rat where they move into some of the cortical areas that are known to degenerate in Alzheimer’s disease. Thus, we propose experiments that will involve injections of human embryonic stem cells into the origin site of this migratory stream in adult and late-life rats, and determine whether these extrinsic cells have the capability to also migrate into these same brain areas. Because our preliminary data indicate that human embryonic stem cells migrate along this route and survive in adult rats, we plan in the proposed study to determine the rate of migration of the injected human embryonic stem cells. In addition, we propose to assess the phenotype of the migrated human embryonic stem cells in these brain areas using an assortment of labeling methods. The last experiment will be performed to determine whether the migrated cells in these brain areas establish synaptic connections with other neurons underlying their functional integration. Together these proposed studies will provide the basis for future clinical trials that are intended to use human embryonic stem cells to replace/replenish degenerating neurons in the brains of aged patients and those with Alzheimer’s disease.
Statement of Benefit to California:
Benefit to California In the next decade, the generation of Baby Boomers will be hitting their sixties and seventies, an age when neurodegenerative diseases, such as Alzheimer’s disease, typically strike. The care and well-being of this elderly population will represent a large expense for the State of California in the near future. Therefore, the development of innovative treatments will be essential for saving health care costs for the State of California. In addition, any new treatment developed in California will directly benefit the residents by creating new jobs and keeping the state’s healthcare on the leading front of biotechnology. These discoveries made in California will lead to start-up companies creating a new economic stream by their licensing the patents generated from this research. Furthermore, California has obtained a leadership role in this field by being the first state in the USA to support Stem Cell Research. Studies such as those proposed in this grant application will lead to the use of human embryonic stem cells for replacement therapy for patients with Alzheimer’s disease. Once these treatments are developed, citizens of the USA will have to travel to California to obtain these new surgical treatments, leading to more business for the doctors and hospitals in California. In summary, California will benefit from this work through cutting edge research, better health care for its aging population, and more jobs and tax revenue resulting from the creation of these new therapies.
SYNOPSIS: This proposal will look at the potential of hESCs to integrate within the pyriform cortex and lateral entorhinal cortex of adult rats. Three specific aims are proposed that build on recent discoveries and work on a new migratory stream in the adult rat forebrain that has potential therapeutic applications in AD and other cortical degeneration issues. Aim 1 will identify grafted hEScs in the brain using HNA and doublecortin to identify the cells at 3 timepoints post-transplantation; Aim 2 will determine the rate and precise route of migration of these cells; and Aim 3 will use EM to determine if hESC-derived cells make synaptic contacts in the piriform and entorhinal cortices. SIGNIFICANCE AND INNOVATION: This investigator has been a productive epilepsy researcher who came upon a new migratory stream in the rostral forebrain of adult rats that has many similarities to the SVZ/RMS olfactory bulb neurogenic system. This discovery, along with preliminary data showing that an hESc line generated by Dr. Kierstead does migrate to the paleocortex, is highly innovative and significant work that can offer insights into future cell replacement therapies for TBI and human neurodegenerative disease. This pathway has been noted in developmental studies. STRENGTHS: This PI has an established track record and high level of expertise in determining functional integration of neurons in cortical (and hippocampal) areas; he is perfect for this project. The pilot data showing hESC in the adult rat piriform and entorhinal cortices following intraventricular injection is interesting and important; this finding warrants the experiments proposed in the Aims (e.g. how many cells will do this – is it significant, and what do they turn into?). This is a very straightforward set of experiments, all falling within the expertise of the 3 investigators on this project, and should certainly answer the questions on survival and integration of hESCs in this novel paradigm. WEAKNESSES: Although the preliminary data provided in the application look pretty nice, it would have been more meaningful if this new migratory pathway had been published (and subjected to peer review of the data) before writing a whole grant application about it. The PI might want to consider studying more than one (the H7) hESC line from the outset, even though such studies are proposed as a follow up; other hESCs from other sources may be useful since they would have been generated possibly differently from those proposed here. Some significant questions remain: What if the cells do not functionally integrate in these cortical areas? The PI proposes to look at other lines, olfactory enrichment, and younger animals if none of the proposed cells and studies show robustness and synaptogenesis, but what if none of these work? There is no real addressing of this potentially serious problem even though the pilot data showing a HNA+/Dcx+ neuron in the cortex following an hESC intraventricular transplant looks pretty encouraging. The applicant has identified a new migratory pathway in the rostral forebrain of adult rats that has similarities to the SVZ/RMS olfactory bulb neurogenic system. The secondary reviewer notes that a few cells get off the olfactory bulb pathway and migrate to the cortex. This migration is not far from the investigator's newly described rostal migratory scheme and the reviewer is not convinced that the presence of a few, rare cells is sufficient demonstration of the existence of a new migration pathway. DISCUSSION: This proposal aims to study hESCs and temporal lobe disorders. Although this proposal appears to be about the discovery of a new neurogenic pathway in the adult brain, the reviewers pointed out that the pathway has already been described developmentally, a point the PI should have noted. Moreover, only a few cells appear to be involved in this novel pathway and these are found not far from the rostral migratory stream - a well described neurogenic pathway in adult brains. One reviewer argued that a few cells could have migrated away off the olfactory pathway, and these ectopic cells could explain what the PI describes as a "new" pathway. Technically, the controls are weak (hESCs would be tested without controls; "test and guess"). One question that isn't addressed is whether hESCs can get into the olfactory bulb and what might be the consequences. A discussant suggested first looking in the mouse to see what kind of neurons they become. It was also not clear how this will this help the Alzheimers'Disease field.