Mouse embryonic stem cells grown in the presence of retinoic acid assume neuronal morphologies, including extensive neural outgrowth, and express neuronal markers such as Tuj1.
Projects
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Mouse embryonic stem cells grown in the presence of retinoic acid assume neuronal morphologies, including extensive neural outgrowth, and express neuronal markers such as Tuj1. |
Our overall goal is to develop stem cell therapies to alleviate neurodegenerative diseases. In one study, we are focused on a class of hereditary diseases called the neuronal ceroid-lipofuscinoses (NCLs; often grouped together under the name Batten Disease). The NCLs are a group of autosomal, recessively inherited, progressive neurodegenerative disorders characterized by the accumulation of autofluorescent lipopigment in various tissues, including the retina and CNS. Children with NCLs are normal at birth but undergo progressive brain and retinal atrophy, and patients with early onset forms of NCL seldom survive past their teenage years. Of the genes responsible for NCLs, Cln1, Cln2, Cln3, Cln5, Cln6 and Cln8 have been cloned and characterized to some extent. We are working on two mouse models of NCLs that exhibit degeneration of the neural retina, one with a mutation in Cln1 and one with a mutation in Cln8. We focus on the retina because the retina and CNS have common embryonic origins, and the retina is easily accessible. In addition, degeneration of the retina is one of the earliest noticeable symptoms of most NCLs.
We are transplanting the following types of stem cells into eyes of the two strains of mutant mice that exhibit NCLs: 1) neuralized mouse embryonic stem cells, 2) mouse retinal neural stem cells (in collaboration with Dr. Michael Young, Harvard University), and 3) neuralized mouse and human mesenchymal stem cells (MSCs, derived from bone marrow; the human MSCs are obtained in collaboration with Neuronyx, Inc.). We are testing whether the transplanted stem cells will (1) become integrated into the degenerating retina as differentiated neurons and glia, (2) remain functionally integrated within the retina indefinitely and (3) secrete normal forms of the Cln proteins and, in the case of Cln1, transfer them to neighboring mutant cells or secrete growth factors that produce neurotrophic effects on host cells. This approach provides the potential to "cure" the host cells and prevent retinal degeneration.
At present there are no effective therapies for any of the NCLs. Our research will provide important new information about the use of stem cells in potential treatments for the NCLs; our hope is that NCLs will become treatable using a combination of gene and stem cell therapy. All the above studies are performed in collaboration with Dr. Martin Katz (Dept. of Ophthalmology, MU) and Dr. Joel Maruniak (Div.Biological Sciences, MU).
In a second study and in collaboration with Dr. Bernie Maria (Medical University of South Carolina, Dept. Pediatrics), we are developing combined gene and stem cell therapies to treat malignant brain tumors. Brain tumors are the most common cause of mortality from cancer in childhood. Malignant tumors of the CNS are highly infiltrative and cannot be surgically removed without significant neurological morbidity. Limitations of current surgical, radiotherapeutic and chemotherapeutic options for treatment of malignant brain tumors motivate development of novel therapies, including gene and stem cell therapies. We are testing whether mesenchymal stem cells can be used to treat pediatric brain tumors. Our working hypothesis is that MSCs, engineered to produce tumor-killing agents, will migrate selectively towards glioma cells and kill them within brain tissue. Mouse and human MSCs derived from bone marrow will be engineered to synthesize tumor-killing agents. The ability of MSCs to migrate towards pediatric glioma cells will be tested in tissue culture. Long-term organotypic cultures will be used to test the ability of MSCs to migrate and kill glioma cells in cortical slices. Finally, transgenic mouse models that form high grade astrocytomas within the CNS will be used to test whether engineered MSCs can infiltrate and kill gliomas under more natural conditions, i.e., within the intact organism. Future applications of combined gene and MSC therapies will provide a unique approach to treating insidious brain tumors while avoiding significant host versus graft disease.