Great progress has been made in the last decades to derive many types of human stem cells for potential therapeutic uses. However, practical clinical use is severely limited by several challenges. One of which is the poor homing and integration of transplanted cells with the targeted host tissues - only very few transplanted stem cells integrate structurally and functionally to the damaged or diseased tissues.
We recently demonstrated that at wounds and damaged tissue sites there are naturally occurring electric fields, which may send a signal to guide cell migration. Excitingly, applied EFs guide migration and division of murine embryonic stem cells(mESCs) and nerve stem cells (mNSCs). We hypothesize that EFs are an effective signal to direct migration of human embryonic stem cells (hESCs), and nerve stem cells (hNSCs) to, as well as engagement and interaction with, sites of tissue damage.
In this proposal, we will establish EFs as a novel signalling mechanisms to guide human stem cells homing and integration. We will optimize electric stimulations to direct migration of hESCs and hNSCs. We will combine the electric stimulation with other treatment to establish a potent and novel mechanism to direct the migration of beneficial human stem cells toward the injury sites to repair and to regenerate.
This visionary endeavor of CIRM to develop stem cell therapies leads the nation and has been galvanizing stem cell researchers to California. This represents the leading role of California at the forefront of biomedical research. Joining this exciting program, we are poised to overcome one of the big hurdles in stem cell therapy - to guide stem cells to damaged and diseased tissues to repair and regenerate. Homing and integration of stem cells to the targeted tissues are critical steps in stem cell therapy. Many types of stem cell therapies have very poor results because of poor homing and integration of transplanted stem cells with the local damaged tissues.
Exploring signals to control cell migration and other behaviors, we have been developing a novel and potentially powerful signal – electric fields for better homing and integration. We propose to understand the electrical control of homing integration of stem cells. If successful, new techniques derived from this project will help to break one of the road locks in stem cell therapies. This grant proposal falls under the mission statement of the CIRM for funding innovative research to achieve effective stem cell therapies. We aim to generate innovative and effective techniques to guide migration of human stem cells. The concept and approach will benefit many types of stem cell therapies.
Techniques developed from this project are expected to significantly increase the efficiency of stem cell to integrate with the host tissues, therefore facilitate restoration of structure and function. If successful, this technique will lead to reduction in the medical and economic burden of large numbers of patients who need stem cell therapies, therefore contribute significantly to CIRM’s mission.
The principal investigator (PI) proposes to study the ability of electric fields (EFs) to guide the migration of human embryonic stem cells (hESCs) and human neural stem cells (hNSCs) and hypothesizes that this may have applications in future cell therapies as a means to guide transplanted cells into the site of injury. In Aim 1, the PI proposes to optimize EF and extracellular matrix conditions to achieve efficient guidance of hESCs and hNSCs on a two-dimensional surface. Aim 2 is focused on studying the role of purinergic and calcium signaling in EF-directed stem cell migration. Aim 3 seeks to develop effective guidance protocols to direct hESC and hNSC migration in three-dimensional gel cultures and in murine brain slices.
Reviewers were uniformly enthusiastic about the proposal’s innovation and creativity, as it is focused on a signaling mechanism, EF, largely neglected in the stem cell field. Furthermore, they appreciated the focus on molecular mechanisms whereby EFs may function to direct cell migration. Although, reviewers were uncertain regarding the potential impact of the proposed studies, since the clinical utility of EFs remains hypothetical, they felt that the proposed studies are likely to provide the initial feasibility and mechanistic data to evaluate those issues in the future.
Reviewers considered this proposal to be carefully designed, and were convinced of its feasibility. The preliminary data show that EFs are an important influence on the migration of various cell types, including mouse ESC, thus supporting the proposal’s physiological relevance. One reviewer expressed concern that the expression of purinergic receptors in hESC and hNSC, a prerequisite for Aim 2, had not yet been confirmed. In addition, reviewers made several suggestions for experimental improvements, including the use of a lentiviral GFP construct instead of DiI labeling to track migrating human cells, since DiI leaks into endogenous cells, thus confounding interpretation. Concern was raised regarding the use of the proposed CO2-independent media, which may not be tolerated well by human stem cells, and the use of a CO2-controlled microscope incubator was recommended instead. Similarly, optimal EF migration conditions may alter stem cell phenotypes, a possibility that should be taken into consideration in experimental design. Notwithstanding these suggestions, reviewers expressed confidence that the proposed studies will lead to important advances in stem cell biology, and were enthusiastic about the studies focused on the interplay between physical forces and biological processes and on the potential utility of these findings for tissue engineering.
Reviewers uniformly praised the PI’s extensive expertise with electric fields and cell migration, and felt that s/he is both clearly committed to this line of investigation and very well qualified to carry out the proposed research. Reviewers differed in their opinions regarding the assembled research team; some felt the collaborators in stem cell biology and neuroscience resulted in a strong team, whereas others felt that their qualifications or commitment to the project were not outstanding. Some of the research personnel critical to the execution of the grant had not yet been identified. The research environment was considered commendable.
In summary, the PI proposes to investigate an understudied phenomenon, the influence of EFs on stem cells, and to determine if it may have utility in directing stem cell migration. Though concerns were articulated regarding certain elements of the experimental design, reviewers praised the PI’s innovative approach, sound preliminary data, strong mechanistic focus, and the project’s potential for making a significant impact on stem cell biology.