The immune system is the body’s first line of defense against pathogens. Immune system cells develop from the fetal liver during embryonic development and then in the bone marrow in adults. Fetal liver and bone marrow stem cells can develop into all of the types of immune system cells. T cells and B cells, two components of the immune system, are important for the control of the immune response against bacteria and viruses, and provide the “memory” of the immune response against same pathogen upon re-infection. As such, healthy T and B cells are crucial to the overall health of the individual. Patients with genetic deficiencies in T cells and B cells often have severe infections and limitations that require lifelong drug treatments. Some immune deficiencies and leukemias can be cured with bone marrow transplantation, but this requires finding a specific matched donor, sometimes impossible to find. Regenerative medicine, which utilizes embryonic stem cells as a primary source of cells, could be an alternative therapeutic approach for these diseases. However, basic information on the biology of embryonic stem cells and the signals which influence their development into specific cell types is needed before regenerative medicine is a reality. The aim of this research proposal is to understand the process by which hESC develop into blood cells, with a particular emphasis on the development of T cells and B cells. We hope to identify cells at specific stages of blood cell development based on the proteins they express on their surface and isolate the stages that are most likely to develop into T and B cells. We will then optimize the culture conditions so that human T and B cells can be efficiently and reliably derived from human embryonic stem cells and used in regenerative therapies for immune deficiencies and cancer.
Statement of Benefit to California:
The research proposed could benefit the State of California and its citizens at several levels. Higher education would be supported by hESC research, as university students seek training and education to allow them to enter this field. The types of degrees earned would not necessarily be limited to biology and health, but could also include economics and sociology to examine the fiscal impact and social impact of hESC research on the state. Health could be improved using regenerative medical therapies aimed at immune system development. Development of protocols to derive lymphocytes reliably from hESC could attract industry and biotechnology companies to the state, an economic benefit both in terms of monetary gain as well as in creation of jobs. All of these benefits, in turn, will attract international attention and recognition to the State of California for being at the forefront of hESC research.
SYNOPSIS: The investigator proposes to define conditions for inducing hESCs to form lymphoid cells. Two specific aims are proposed. Specific Aim1: To define human lymphoid progenitor cells via expression of specific cell surface markers and functional in vitro T and B commitment assays. CD45-PFV+ hemangioblasts will be isolated and grown in various cytokines prior to FACS analysis to detect Common Lymphoid Progentitors (CLP). Specific Aim 2: To establish reliable, high efficiency lymphoid-inducing culture conditions to produce T and B cells from hESCs and test the hypothesis that the T vs B lymphoid cell fate decision in hESC-derived lymphoid precursors is dependent on the amount of Notch signal received. CLPs will be co-culture on various stromal cell lines and notch levels modulated by chemical inducers or inhibitors or addition of soluble notch ligands. The investigator will also evaluate human lymphopoieses in immunodeficient mouse strains. INNOVATION AND SIGNIFICANCE: This is a proposal by a young, well-trained immunologist. It is an interesting look at the differentiation of lymphocytes from hESCs. These are largely descriptive studies which seek to address problems already being explored in other labatories. As such they cannot be considered very innovative. Although this approach is not new, Notch signaling to effect lymphocyte differentiation has not been reported for hESCs and the attempt to define the dose dependence of development of human T and B cells will be a useful contribution, as part of an effort to define better methods for efficient identification and selection of these hESC-derived cell populations. STRENGTHS: Investigator is well-trained as a graduate student and post-doctoral-fellow in experimental immunology. As a graduate student the investigator had good productivity working with Dr. Sikes (four papers as first author and two others between 1988 and 2003) and two in 2005. WEAKNESSES: The main weak points derive from the absence of significant experience of the PI on hESCs or resident experts, although the PI will be trained by Dr. Tarantal, from UC Davis. The proposal is limited in scope and seems unlikely to yield critical new information or hypothesis; it mostly attempts to optimize assays.The enviroment at Merced may not be supportive for new investigators who want to begin in this field. DISCUSSION: There was no further discussion following the reviewers' comments.