WNT signaling in neural stem cell self renewal and neural crest cell specification and migration
Human pluripotent stem cells (hPSCs) and their derivatives represent the only research tool to study human development. As
such, these cells allow us to study the progression of diseases at the cellular level in a dish, probe how specific genetic defects
contribute to the myriad of developmental and birth defects, and generate the “raw material” for the development of cell-based
therapies of presently incurable diseases, such as cancer, cardiovascular disease, and neurodegenerative disorders. However, our
understanding of the basic mechanisms underlying stem cell biology is incomplete, and the processes by which individual cells
organize each other to give rise to the complexity of multi-cellular life remain mysterious.
At the heart of embryonic development lies an intricate process of cell communication. Individual cells within the developing
organism produce and release signals, known as growth factors, that instruct neighboring cells to assume specific behaviors and
properties. Unique combinations of such growth factors regulate a multitude of developmental processes, including the growth
and differentiation of hPSC. Wnt proteins represent a major class of growth factors with potent effects on stem cells and
developmental processes. However, despite 30 years of research on these proteins with over 1,800 publications in 2010 alone,
the mechanisms by which Wnt proteins elicit specific cellular responses and regulate stem cell biology remain poorly
One reason for the slow progress in the study of Wnt proteins is that their manipulation in biological systems has been difficult
and even impossible. We have developed powerful technologies that allow us to systematically dissect the role of Wnt signaling
in regulating the behavior of hPSC. By developing the means to isolate Wnt proteins we are now able to examine their effects on
stem cell growth and differentiation. We will specifically examine the role of Wnt signaling in neural stem cells, a cell type that
can generate many of the cells found in the central nervous system (CNS). In addition, in collaboration with our research
partners [REDACTED] we propose to examine the effects of Wnt signaling in Axolotl, a newt with remarkable regenerative
potential in the CNS. By performing a comparative analysis between human and Axolotl neural stem cells we will be able to
identify the unique properties that allow efficient regeneration of the Axolotl CNS and apply this knowledge to design strategies
for stimulating regeneration of the human CNS. By identifying the mechanisms by which Wnt proteins act we will contribute
valuable tools and protocols for the manipulation and specific differentiation of hPSC and neural stem cells into mature cell
types that can be utilized in cell replacement therapies. Additionally, these studies will pave the road to designing strategies
that stimulate cells in the central nervous system to repair damage.
The rise in life expectancy to over 80 years will likely lead to an increase in the number of people suffering from age-related
diseases, such as cancer, heart disease and neurodegenerative disorders. Current medical treatments can control, but not cure,
such diseases. Recent advances in the study of human pluripotent stem cells (hPSCs) have provided the opportunity to develop
novel cell replacement therapies for the treatment of many such diseases. Development of novel cell based therapies will also
overcome the inadequacy of conventional drug-based treatments.
Several scientific obstacles need to be overcome before the full potential of hPSC-based therapies can be realized. First,
sufficiently large numbers of clinical grade hPSC that can be thoroughly tested and characterized need to be derived. Second,
robust protocols for the directed differentiation of hPSC into functionally mature cell types suitable for transplantation need to
be developed. To address these challenges we propose a set of experiments that will significantly expand our understanding of
basic biology of hPSCs and one of their descendants, neural stem cells.
One powerful approach to affect hPSC behavior is through the manipulation of the extracellular environment. We are
particularly focused on one class of potent stem cell factors, called Wnt proteins. We and others have shown that Wnt proteins
can dramatically affect the growth of stem cells so that Wnt-stimulated cells in some cases grow more robustly or in other cases
produce specific mature cell populations. These experiments will enable the development of cost-effective protocols for the
large-scale production of undifferentiated hPSC and functionally mature cell types. Our proposed research is fundamental to
applications of hPSC in regenerative medicine and has broad benefits to researchers with a wide spectrum of scientific interests.
This research will not only benefit the health of Californians, but also the California economy by developing new reagents,
protocols and technologies that will be adopted by existing companies as well as seed and complement novel business ideas.
The outcome of this project will contribute to the development of a biotechnology platform that can provide great benefits to
the advancement of California biotechnology. The patents, royalties and licensing fees that result from the advances in the
proposed research will provide California tax revenues. Thus, the current proposed research provides not only the essential
foundation for the scientific advances in regenerative medicine to improve health and quality of life, but also potential
technology advancement and financial profit for the people in California.