Development of a low cost, turbulence-free, compact bioreactor for the culture and expansion of stem cells
Tools and Technologies II
One of the key resources needed to harness the full power of stem cells for basic research, or drug discovery or clinical application is the availability of a bulk supply of well characterized cells with consistent growth properties, cell surface markers and responses. The current proposal explores the use of a novel, cost-effective bioreactor to achieve this goal. From the basic research point of view availability of consistently behaving stem cells will, at a minimum help generate comparable data across laboratories. From the drug discovery angle the impact of the proposed research are many. Considering chemically induced stem cell differentiation (CISD) is an emerging field with huge potential in regenerative medicine, the value of HTS in identifying small molecules that potentially can induce differentiation and those which help maintain and prolong stem cell survival cannot be over stated. An inexpensive source and an almost endless supply of consistently behaving stem cells will make high throughput screening (HTS) of millions of compounds possible and more importantly make it financially feasible. The data obtained using these cells will be robust, reproducible and transferable from laboratory to laboratory and institution to institution. Availability of stem cell derived human cardiomyocytes, neuronal cells and hepatocytes (and other cell) “banks” are excellent tools for predicting clinical outcomes of potential drug candidates early in drug discovery. In addition, the method developed would set the stage for generating large quantity of cells in an automated and reproducible manner with minimum labor which could be used for clinical research and for much promising cell therapies.
Statement of Benefit to California:
This project proposes to develop efficient methods for culturing and expansion of large quantities of stem cells. As described in the proposal, availability of bulk supply of well characterized stem cells with consistent growth properties, cell surface markers and responses is key to advancing basic, preclinical as well as clinical research in regenerative medicine. In this regard, the proposed project is a powerful enabling technology, which is bound to have a broad impact on many areas of stem cell research. Thus, the proposed work is not only in line with the mandate proposed by the citizen’s of CA, but also the data from the proposed research are expected to open up additional research and business opportunities. These research and business opportunities have the potential to create substantial number of jobs within the state of CA and infuse significant amounts of capital (and revenue) in the form of grants, investments, intrastate and interstate commerce into the state. In addition, all work will be done in the state of CA and reagents and supplies from CA vendors will be used in the research.
The goal of this application is to develop a turbulence-free bioreactor for culturing pluripotent stem cells (PSCs) that mimics high-density in vivo cell growth. There are three objectives proposed in the research plan: (1) To determine if the proposed biomimetic and turbulence-free three-dimensional (3D) culture system can be used to maintain and expand human pluripotent stem cells; (2) To examine the stability of the expanded PSCs with regard to their phenotypes, genotypes, differentiation capacity, and pharmacological responses; and (3) To test the reproducibility of the system in terms of the quality of the PSCs and their suitability for pharmaceutical evaluation. The reviewers had serious reservations regarding the underlying rationale of this proposal and were not convinced that it addresses a translational bottleneck. The applicants postulate that turbulence and shear stress are critical bottlenecks in the successful expansion of stem cell suspension cultures, but do not present compelling preliminary data or sufficient literature references to establish that this is in fact the case. Reviewers noted that while turbulence and sheer stress may indeed be negative factors impacting successful expansion of PSCs, there may be other factors that contribute to successfully expanding cells. Thus, it would be preferable to systematically explore these issues before locking in on a specific bioreactor system upfront. In addition, the lack of detail provided in the application made it difficult to assess what is novel about this bioreactor system and why it would reduce turbulence and shear stress. Reviewers also expressed reservations about the experimental design. The preliminary data did not include any data on the culturing of human embryonic or induced pluripotent stem cells. A hybridoma comparison was included, which does not address unique stem cell issues. Reviewers found fault with the lack of detail in the proposal. For example, they noted that the matrix is not sufficiently defined nor are any details presented as to how cells will be harvested. Additionally, the proposal for characterizing stem cells derived from the bioreactor omits the key step of in vivo teratoma formation to establish that truly pluripotent cells are derived from the bioreactor (the application states that they will be testing for pluripotency, but does not specify how) and there is no consideration given to characterizing cells for epigenetic changes. Reviewers also had concerns about higher density cultures having an unintended feedback between cells. In addition, the goals of the project were not expressed in quantitative terms, and the risks and mitigation strategies were not well developed. In general, reviewers described the proposal as vague and lacking sufficient detail to allow estimation of the probability of success. The reviewers felt that the industry backgrounds of the applicants were strengths. However, the team would have benefited by including a stem cell biologist or consultant in the stem cell field. One reviewer noted that several additional staff will need to be hired to perform this work, which suggested a delay in initiating the project and meeting milestones. Further detail is needed to justify the budgets proposed for supplies and equipment. In summary, this application describes the design of a turbulence-free bioreactor for high-density PSC culture. The reviewers raised several concerns regarding both the rationale and experimental design of the project, and did not recommend this application for funding.