Depletion of Teratoma-Forming Cells for hESC-Based Transplantation Technologies

Funding Type: 
Early Translational I
Grant Number: 
ICOC Funds Committed: 
Public Abstract: 

The successful development of human embryonic stem cell (hESC) based therapies to treat human disease will hinge upon the preparation of high quality cells for implantation, as heterogeneous cell preparations can pose a safety risk to the patient and even compromise efficacy. In particular, implantation of differentiated cell populations with heterogeneous composition into numerous tissues, including muscle and brain, can lead to teratoma formation due to undifferentiated cell contaminants in the graft. Furthermore, inappropriately differentiated cells can lead to adverse side effects. Therefore, cell graft quality remains a major bottleneck for human embryonic stem cell based regenerative medicine efforts.

We have assembled a strong team – with highly complementary biological, engineering, and clinical expertise – to address this critical bottleneck by applying advanced technologies for cell differentiation and purification. First, we have developed a novel microfluidic cell separations system in which surfaces are functionalized with antibodies against key cell surface markers, and the subsequent microfluidic flow of a cell suspension over these surfaces results in spatial separation of cells based on expression of these markers. This scalable system will be applied towards the purification of high quality differentiated cell preparations. Second, stem cells arguably differentiate heterogeneously in culture in part because, in contrast to native microenvironments that present them with regulated signals to control their function, typical culture systems expose them to heterogeneous and contradictory conditions that imprecisely control cell behavior. Synthetic, bioactive materials presenting biological signals will be utilized to provide chemically defined and homogeneous conditions for uniform cell differentiation.

Graft quality is a bottleneck for most disease targets, and we propose to test these technologies in two critical tissues: skeletal muscle and brain. Specifically, human embryonic stem cells will be differentiated into skeletal muscle cells and dopaminergic neurons – using both established differentiation conditions and bioactive materials engineered for this application. Cells will in some cases be purified prior to implantation into animal models of skeletal muscle injury and Parkinson’s Disease. We propose that parallel progress in cell differentiation and purification technologies will enhance both the safety of the graft, by reducing the incidence of teratoma formation, and potentially its therapeutic efficacy in these important animal models of human disease and injury.

Statement of Benefit to California: 

This proposal will address a critical bottleneck that impedes the translation of pluripotent stem cells to the clinic. By overcoming this bottleneck, this project will strongly enhance the biomedical, technological, and economic development of stem cell therapeutics in California. The most important net benefit will be for the treatment of human diseases.

Specifically, the tumor-forming properties of human embryonic stem cells (hESCs) are part and parcel with their advantageous properties of continuous self-renewal and pluripotent differentiation; however, they also pose considerable challenges for their safe use in humans. In particular, any serious adverse events in a clinical trial involving hESC-derived cells will severely damage the field. Therefore, the ability to deplete tumor-forming cells from populations of cells differentiated from hESCs will greatly enhance their clinical safety, as well as their utility as models of human disease and development.

The coupled technology platforms to be used in this proposed work – microdevices for cell separations, and more homogeneous cell culture and differentiation systems based on bioactive materials – have broad applications not only for stem cells but also many other scientific and biomedical efforts, such that the results of this project will enable many fields. Furthermore, this proposal directly addresses several central objectives of this RFA – pre-transplant manipulations of cells to prevent teratoma formation, as well as development of cell differentiation and purification methods that result in more consistent yield of cells of the desired phenotype, and that are scalable and more cost-effective – indicating that CIRM believes that the proposed capabilities are a priority for California’s stem cell effort.

While the potential applications of the proposed technology are broad, we will first apply it to two specific and urgent biomedical problems: the depletion of teratoma-forming cells from hESC-derived populations of myocytes and dopaminergic neurons. By assessing the performance of this technology in two models of human disease, the preclinical impact of the work will be directly established. Furthermore, in addition to enhancing the safety of tranplanted cells, this work has the short and longer term potential to greatly increase the uniformity and yield of therapeutically important cells derived from hESCs, thereby potentially impacting therapeutic efficacy.

The co-investigators have a strong record of translating basic science, engineering, and medicine into practice, both through medical schools and interactions with biotech companies in California. In addition, this collaborative project will focus diverse research groups with many students on an important interdisciplinary project at the interface of science and engineering, thereby training a future workforce and contributing to the technological and economic leadership of California.