Basic Biology I
A fundamental characteristic of immune cells is their capacity to interact and form signaling networks with each other, as this ability is essential for providing a timely and comprehensive immune response. Human embryonic stem cells (hESC) and induced pluripotent stem cells (iPSC) have been shown to have the potential to differentiate into a number of different cell types, including the blood cells involved in the immune response. However, the functional properties of those cells, including their ability interact and communicate with each other, have never been fully evaluated. Hence, the goal of our proposal is to establish whether the hESC/iPSC-derived immune cells have the capacity to interact and form signaling networks with each other in a physiological manner necessary to generate a functional immune response. This is an important basic science question as it closely evaluates the quality of the cellular differentiation process of hESC and iPSC into functional immune cells, providing insights into hematopoietic developmental pathways of hESC/iPSC. In addition, if functional abnormalities in hESC/iPSC-derived cells are observed, the wealth of information we will obtain in our work will provide a starting point to investigate this issue and may help us to design strategies to correct such defects.
Statement of Benefit to California:
Hematopoietic stem cell therapies have been used for the last fifty years for different medical treatments in California and throughout the world. The research on human embryonic stem cells (hESC) and induced pluripotent stem cells (iPSC) has created a substantial excitement in medical community, as these cells for several technical reasons may even be better suited for some of these therapies. However, a number of questions regarding hESC and iPSC need to be addressed before they can be moved to the clinic. Our research proposal examines very closely one of those issues. Namely, we seek to establish whether the hESC and iPSC-derived immune cells have the ability to interact and communicate with each other in a functional manner, which is a major prerequisite for an effective immune response. Hence, in this matter, our work will help establish whether hESC/iPSC-derived cells are really suitable for reconstitution of functional blood lineages. If not, the wealth of data we will obtain in the process may help us correct the problem. Therefore, this project may accelerate clinical application of hESC and iPSC leading to better hematopoietic therapies. New and better treatments for blood disorders or hematopoietic stem cell replacement therapies are certainly going to benefit the people of California.
The goal of this proposal is to evaluate the capacity of immune system cells derived from embryonic stem cell (hESC) or induced pluripotent stem cells (iPSCs) to generate a functional immune response. Specifically, the applicant will use hESC or iPSC-derived antigen presenting cells (APCs) to activate antigen specific T cell derived from hESCs or iPSCs. The ability of these activated T cells to kill target cells carrying the antigen will then be evaluated in vitro and in vivo. The investigator will also evaluate the ability of derived APCs to mediate negative selection of derived thymocytes in in vitro and in vivo models. Reviewers agreed that this proposal addresses a major unsolved problem and could have significant impact on the development of hESC or iPSC-based therapies for immune diseases and cancer. They found the proposal innovative, particularly Aim 1, which one reviewer called a potentially quite novel and profound means of promoting anti-tumor immunity. However, this reviewer found Aim 2 to be less significant and innovative and was unsure it would provide meaningful results beyond a proof-of-principle. In terms of experimental design and feasibility, reviewer opinions were again split between the two aims. The reviewers universally praised Aim 1, describing it as clear, well conceived, highly innovative, and supported with good preliminary data. One reviewer did note the lack of evidence of hematopoietic development from iPSCs but commended the data from hESCs. The main deficiency in this aim was a lack of proposed alternative strategies. The reviewers were significantly less enthusiastic about Aim 2. They found Aim 2 to be less well conceived and designed. One reviewer found the approach a bit naive, as induction of thymic selection is a complex event in which T cell fate (deletion or generation of tolerogenic or activated T cells) is determined by the precise coordination of the specific expression of cell surface markers on T cells located in specific regions of the thymus and the timing of antigen presentation. This reviewer wanted this aim to be more developed given it is a potential mechanism for the development of immune tolerance. Another reviewer commented that the rationale for using this model is not clear and the outcomes are ill defined. Reviewers noted that no alternative approaches were outlined for Aim 2. Reviewers praised the applicant's experience and track record pioneering the derivation of T cells from hESCs. However they noted that the two primary author papers describing this work are the applicant's only significant primary or senior author publications. One reviewer had difficulty evaluating the independence of this young investigator from the postdoctoral advisor. Reviewers did praise the strong group of collaborators assembled and found the research team well qualified to carry out the proposed research, but thought the proposed work would benefit from the addition of a more experience investigator to the team. Overall, the reviewers agreed that this proposal addresses an important problem in developing hESC- or iPSC-based cell therapies and were impressed by the significance, innovation, and feasibility of Aim 1. However, they raised a number of concerns about the significance, innovation, and feasibility of Aim 2 that decreased the enthusiasm of the reviewers for this proposal.