Modeling and correction of genetic skeletal dysplasias in iPSCs
Achondroplasia is the most common form of skeletal dysplasia, a disease of the bone and cartilage that is characterized by short-limbed dwarfism. Achondroplasia is known to be a heritable genetic disorder, and the gene believed to be responsible is FGFR3. Genetic alterations in FGFR3 are found in most cases of achondroplasia, but how they influence disease progression remains poorly understood. While mouse models of achondroplasia exist, due to the inherent differences in physiology between mice and humans, these models cannot inform scientists of the detailed processes controlling human disease progression. Indeed, this gap in our knowledge has prevented us from completely understanding achondroplasia and inhibited the development of new treatments for this disease. Our laboratory has developed techniques that allow for precise modification of cellular genomes. These techniques are based on zinc finger nuclease (ZFN) proteins that can be designed to modify DNA at a targeted location in the human genome. We are proposing to use ZFNs to recreate the specific gene mutations found in a majority of achondroplasia cases in laboratory based human cell lines. These cell lines will then be used to create induced pluripotent stem cell (iPSC)-based disease models of achondroplasia. iPSCs are cells that have the potential to develop into almost any cell type or tissue. By creating iPSCs that have the mutations associated with achondroplasia, we will be able to monitor the progression of the disease throughout the developmental process by monitoring the formation of bone tissue from stem cells. This strategy will provide a very accurate model of achondroplasia and will allow us to reveal mechanisms controlling disease progression and bone formation. In addition, the generation of iPSC-based models of the disease will permit the development of novel therapies that can be initially analyzed with these cells. Finally, we will use ZFNs to genetically correct the FGFR3 gene in cell lines obtained from patients with achondroplasia. By comparing these corrected cell lines to the disease models we create, we will be able to confirm that the assumed causative FGFR3 mutations are responsible for achondroplasia.
Stem cell technologies hold the potential to revolutionize medicine, healthcare, and our understanding of human biology. Induced pluripotent stem cells (iPSC) are cells that can be generated from adult tissues and used to give rise to several different cell types. Stem cells hold vast potential for the treatment of disease and injury because they are pluripotent: these cells have the ability to develop into any of the more than 200 cell types in the human body. Our research goal is to use iPSC technology to generate stem cell-based models of the disease achondroplasia. Achondroplasia is the most common cause of skeletal dysplasia, a congenital abnormality of the bone and cartilage that is characterized by short-limbed dwarfism. While some of the genetic factors underlying the disease are known, much about the development and pathology of the disease is unknown. These gaps in our understanding are due to the fact that human-based laboratory models of the disease do not exist. While mouse models are useful for developing insight into human disease, they often cannot reveal the mechanisms of a human disorder. However, with iPSCs we will be able to generate a wide range of disease in the dish models of achondroplasia. Accurate models of human disease will allow for precise study of the underlying mechanisms and the development of new therapies. Scientists believe that stem cells can eventually be used to create therapies to treat previously untreatable injuries and diseases. Devastating and currently incurable conditions such as AIDS, Alzheimer’s, liver disease, diabetes, Parkinson's disease, muscular dystrophies, spinal cord injuries, inborn errors of metabolism, and many other diseases can be studied by creating disease in the dish models with iPSCs. However, in order to realize the full potential of this technology, researchers need to develop new tools that will permit the safe introduction or correction of genes in iPSCs. To achieve this significant goal, we will capitalize on our extensive experience in developing new and effective gene targeting technologies to derive and characterize unique stem cell-based models of achondroplasia. This new technology and the new therapies that may result from this research may result in the reduction of the long-term healthcare costs to the State of California by providing cures and alternative treatments to disease and injury that are chronic and/or untreatable. Support for the development of this new technology will ensure that California is a leader in stem cell technologies, making California better equipped not only to treat its own citizens but also to compete for the multi-billion dollar market that is expected to develop with advances in stem cell technologies. Spurring industry, research, and product development in the biotechnology and healthcare fields will further benefit California by attracting highly skilled and well-educated individuals and tax revenues to the state.