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RN1-00539-1: Directed Stem Cell Recruitment into the CNS in Response to Coxsackievirus Infection
Recommendation: Not recommended for funding
Public Abstract (provided by applicant)
Improved and more effective treatment strategies to alleviate the clinical symptoms associated with multiple sclerosis (MS) remain problematic. A better understanding of stem cell migration across the blood-cerebral spinal fluid (CSF)-barrier and targeted differentiation may assist clinicians and researchers in maximizing the efficacy of stem cell based therapies. Many previous studies utilizing stem cell therapy for tissue regeneration have relied on the seemingly inherent ability of stem cells to migrate and differentiate somewhat haphazardly into predetermined areas in damaged tissues. However, the random inoculation and migration of stem cells, regardless of regenerative potential, is unlikely to lead to the most efficient recruitment of stem cells and subsequent repair of critically damaged regions . Utilizing our neurotropic viral infection model which appears to induce the recruitment of peripheral stem cells, we will attempt to characterize stem cell migration across the blood-CSF-barrier and determine necessary recruitment factors upregulated during infection. Additionally, we will test the ability and advantages of utilizing an attenuated recombinant coxsackievirus as a novel viral vector for gene transfer into stem cells. The ability to insert foreign genes into stem cells may assist in proper stem cell differentiation and protection from the host immune response. Finally, we will evaluate the therapeutic use of stem cells transduced with an attenuated recombinant coxsackievirus utilizing a relapsing-remitting mouse model of MS. MS is thought to be an autoimmune disease in which the loss of myelin contributes to central nervous system (CNS) damage and clinical disease. Stem cell transplantation may be a therapeutic approach for the re-establishment of myelinated axonal fibers and proper neuronal function. The addition of foreign genes into stem cells may help protect the newly differentiated cells from suffering from the same fate as their non-functioning neighbor cells. We hope that the proposed research will assist in the development of novel reagents for optimized stem cell therapy in patients suffering from neurological diseases.
Statement of Benefit to California (provided by applicant)
Approximately 400,000 Americans suffer from the neurological symptoms associated with multiple sclerosis (MS). The therapeutic use of stem cells may provide the basis for improving the lives of patients suffering from MS, and a variety of other neurological diseases. However, much remains to be understood regarding productive stem cell migration and proper differentiation of oligodendrocytes in the host. Oligodendrocytes are essential cells in the central nervous system (CNS) that help to protect the axons of nerve fibers by producing a fatty tissue called myelin. In MS, myelin is lost in many region of the CNS thereby producing sclerotic lesions. Hence, the ability to promote new myelin formation in damage regions by the addition of new oligodendrocytes may be a potential therapy for the alleviated the effects of clinical disease. The project will provide new insights on how stem cells may traverse through the blood-brain-barrier and differentiate into the various cell types found within the CNS. Furthermore, we will test the ability of using a well characterized coxsackievirus that efficiently infects stem cells as a viral gene delivery system. Our hope is that the information gained from our efforts will point to new directions, whereby optimized stem cell therapy may be of great benefit to those suffering from MS, and other neurological disabilities.
Review
SYNOPSIS: In this proposal, the applicant plans to use a neurotropic virus infection model as means to explore chemoattractant molecules that influence the migration of stem cells into the CNS, and to evaluate a recombinant coxsackie virus as a viral vector to transduce neural stem cells. The applicant will then transduce neural stem cells (NSC) to attempt to ameliorate experimental autoimmune encephalomyelitis (EAE) in a murine model of multiple sclerosis.
STRENGTHS AND WEAKNESSES OF THE RESEARCH PLAN: This is an interesting application from a young investigator with insight into the potential importance of findings somewhat tangential to coxsackie meningitis. This work originates from the PI’s post-doctoral studies and his/her published observations, that the recombinant neurotrophic virus targets proliferating neural progenitor cells in the neonatal CNS. As the PI notes, the ability of stem cells from the periphery to contribute to repair remains controversial.
There are a number of strengths to this proposal. The Preliminary Data of the PI is of interest and involves creative experiments. The identification of the relationship between a virus infection and stem cells is of interest and provocative. However, the specific aims of this present proposal seem somewhat disconnected. The proposal generally did not seem well-unified.
It is a major concern that the PI states right at the beginning of the proposal that the experiments may be risky. The first aim involves a controversial issue in stem cell (SC) biology. The relationship between the peripheral stem cells and NSCs remains unclear. It is not entirely clear how the applicant would use the information generated from the first aim in therapeutic approaches. Will the chemoattractants that the applicant finds affected in the neonatal mice have relevance to the recruitment of stem cells into the adult CNS? The use in the second aim of coxsackie virus as a vector for gene delivery may have problems related to maintenance and stability of the foreign gene. The reviewers were uncertain why the PI chose coxsackie virus as the vector for these experiments.
Beyond these general critiques, detailed concerns with the experimental approach are discussed below. One reviewer highlighted a number of concerns in the experiments involving chemoattractants. These kinds of experiments may not provide clearly positive information if more than one factor may be necessary for the transformation of the precursor cells. To one reviewer, preliminary data were not convincing that a sufficient number of injected cells will enter into the CNS, complicating the successful completion of these studies.
In the second aim, the PI will evaluate different coxsackie viral vectors for gene delivery into SCs for experiments planned in the third aim. There are several questions and issues that arise with respect to this specific aim. The rationale for choosing coxsackie virus provided by the PI includes the stability of the genome and its long-term expression and persistence. However, there are reports of instability of foreign genes placed into picornaviruses, including enteroviruses as well as cardioviruses – so that part or all of inserted genes may be lost, especially during proliferation of SCs. There is limited space within the enterovirus genome, so that large inserts may foster deletion or limit infectivity. Furthermore, it is not clear how common persistence of enteroviruses is — or whether this is an advantage or disadvantage to persistence. It was unclear why the PI chose coxsackie virus for gene delivery since there are other viruses that are frequently used as vectors. Would another virus be preferable to use, especially one that is more commonly used?
In the third aim, the PI will test whether coxsackie virus-transduced NSCs have an effect on EAE. An issue with respect to this third aim was its relationship with the specific aim 1. What is the relationship between a treatment of EAE and the identification of chemoattractants that guide the specific precursor subpopulation?
QUALIFICATIONS AND POTENTIAL OF THE PRINCIPAL INVESTIGATOR: The applicant is ideally suited to carry out this project. The timetable and the PIs enthusiasm for this project indicate that five years of funding would successfully convert a virologist into a stem cell scientist with specialized tools for stem cell fate determination.
The applicant just recently assumed his/her present position as Assistant Professor. The PI received a PhD in 1999, and then pursued a post-doctoral fellowship from 1999-2004. He/she continued to work in the same lab from 2004-2007, which is an outstanding one with respect to training in virology and immunology.
The PI was first or last author on ~5 refereed papers in specialty journals since 2002; these papers have focused on viral pathogenesis studies and are of high quality. One wonders whether the publication record is relatively modest considering the fact that the applicant is 8 years out from his/her PhD. The applicant was recently awarded an RO1 grant in related work. The applicant was named a Young Investigator Award Finalist at a relevant conference.
The applicant was trained principally in neurovirology, and now wants to apply this expertise to stem cells. In the first instance the applicant targets MS, but hopes that the generated results may apply to neurodegenerative disorders, such as Parkinson’s disease in the future. It is not clear whether the PI had any formal training in the SC field which may be both a plus or negative with respect to this proposal, i.e., CIRM has the opportunity to strengthen an interest in SCs in someone who has expertise in immunology and virus pathogenesis studies. There was some concern that the applicant would be somewhat isolated with respect to his/her scientific environment.
INSTITUTIONAL COMMITMENT TO PRINCIPAL INVESTIGATOR: The applicant recently assumed his/her present position as Assistant Professor. The applicant is presently in a recently renovated lab of ~1000 sq. ft. and received a reasonable start-up package. There is a FACS facility, microchemical and DNA array \cores, a vivarium including a BSL-2 facility, and access to a confocal microscope. The applicant holds an Adjunct Assistant Professor status at another institute, which gives him/her access to these core facilities. There is a tenure-track committee.
It would be most advantageous for the applicant to have an interactive scientific environment, so that the PI has contact with individuals in the SC field on a frequent basis. Although the institution appears to be a nurturing environment, one is concerned that there are very few individuals at the institution who have a general interest in SCs. One wonders whether the applicant may be somewhat isolated. It is true that his/her prior collaborations are bound to be helpful, but it remains unclear how effective these will be.
DISCUSSION: The reviewers were in agreement that the relationship between the Coxsackie virus and neural stem cells is intriguing. However, the significant concerns with the research proposal reduced enthusiasm for the application. Reviewers felt that the proposal was not well integrated, citing that the second aim doesn’t belong in this proposal, and it is unclear how well integrated the third aim is with the others. The main problem with the application is with the focus on coxsackie virus. Other concerns with the application included: that the choice of markers may not be specific to neural cells, that the PIs choice of language to report on findings in the EAE model suggest naiveté with this aspect of the project, and that eight years out of his/her training the PI doesn’t have any real home-run papers. A case was made in favor of the application that since SC migration into and out of the brain is an unknown, finding any chemoattractant would be a real step forward for the field. With respect to the level of institutional support, opinions among the reviewers differed. Comments ranged from one reviewer noting that institutional support and mentorship are not as strong in this proposal as in others, to another reviewer saying that the institutional support seemed quite high, given that the institute is trying to put a program together. The discussion closed with the impression that the insufficient biology and research plan could not overcome the interest in the initial concept.
The following Working Group members had a conflict of interest with this application and were therefore recused from participating in review of, discussion of, and voting on the application:
- None