Basic Biology V
$1 161 000
Congenital and childhood sensorineural hearing loss (SNHL) is a multifactorial, complex disease that severely impacts quality of life. The single most important etiology of congenital SNHL is prenatal human cytomegalovirus (HCMV) infection, accounting for 20-30% of all deafness in infants and children. This may be an underestimate, as most newborns are not routinely screened for HCMV infection. SNHL can be either bilateral or unilateral, and the severity of the hearing loss as well as its progression varies widely. Although the association of congenital HCMV infection and SNHL has been recognized for 50 years, how HCMV induces the hearing loss is unknown, particularly in cases of delayed SNHL. Embryonic stem cells (ES) provide an abundant source of precursors that can be differentiated to neural cells. We have developed a method to induce differentiation of human ES into progenitors that can be further differentiated to hair cell-like cells and auditory neurons in the inner ear. The goal of our proposed studies is to determine how HCMV infection compromises the function of human ES-derived inner ear cells and to use this information to develop new strategies for the treatment and prevention of hearing loss in congenitally infected children.
Statement of Benefit to California:
Congenital and childhood sensorineural hearing loss (SNHL) is a multifactorial, complex disease that severely impacts quality of life. The single most important etiology of congenital SNHL is prenatal human cytomegalovirus (HCMV) infection, accounting for 20-30% of all deafness in infants and children. In 2011, there were 502,203 births in California, resulting in congenital HCMV infection in approximately 5,000 newborns, with at least 800 infants expected to have long-lasting disabilities. In contrast, before the development of the rubella vaccine, less than 70 infants per year in the entire US were reported to have congenital rubella syndrome, also associated with deafness. The burden to families and the economic costs to society of congenital cytomegalovirus infection are immense, and there is no vaccine available. Our proposed research builds upon our novel finding that HCMV directly alters the regulation of genes critical for cochlear development. It will serve to form the basis of future therapies to ameliorate this serious medical burden. Our research will provide the knowledge base to understand the mechanisms by which HCMV infection leads to SNHL. It will also provide a foundation for studies of how specific changes in cells in neural and sensory cell lineages contribute to deafness. Intellectual property from this work will also feed into opportunities for antiviral strategies and increased jobs in the biotech industry for Californians.
Congenital and childhood sensorineural hearing loss (SNHL) is a multifactorial, complex disease that impacts quality of life. The single most important etiology of SNHL is prenatal human cytomegalovirus (HCMV) infection, accounting for at least 20-30% of all deafness in infants and children. However it is unknown how HCMV induces the hearing loss particularly in cases of delayed SNHL. Cytomegalovirus is species-specific, and thus in vitro models are essential for studying effects of HCMV infection on the developing human brain and organ-specific precursors. Embryonic Stem Cells (ESCs) provide an abundant source of precursors that can be differentiated to neural cells. The goal of this The goal of this Fundamental Mechanisms Award proposal is to determine how HCMV infection compromises the function of hESC-derived inner ear cells and to use this information to develop new strategies for the treatment and prevention of hearing loss in congenitally infected children. This will be done in vitro (Aim 1) by infecting hESCs or otic progenitors derived from these cells and assaying for disruption in differentiation to mature sensory hair cells or auditory neurons, and in vivo (Aim 2) in an animal model where the human ES-derived otic neuroprogenitor cells are engrafted in the ear with HCMV infection before or after engraftment. Significance and Innovation - This project tackles a significant problem in that hearing loss is clearly an important medical problem and CMV infection is a major cause of congenital hearing damage. - The rationale behind this study is that it is necessary to study human cells to understand the process by which CMV interferes with the differentiation and survival of developing cells of the inner ear, as viral interactions are species specific, however, it was difficult to know from this application what the impact of this study would be, as the importance and value of the project is not well justified. - The use of the proposed nonhuman animal model is questioned regarding relevance. Feasibility and Experimental Design - The preliminary did not always support the feasibility to perform the experiments proposed. - Reviewers found major flaws in Aim 2. No evidence was provided that function can be restored with primary mouse cells in a rodent model. -No data was presented to demonstrate the suitability of the animal model selected for Aim 2. - Some reviewers were not convinced with the data presented that the hESC-derived cells are properly differentiated into the functional otic cells. - Appropriate facilities are available to conduct the proposed research. The environment is appropriate to successfully complete the project. Principal Investigator (PI) and Research Team - The PI has an established track record of publishing and is capable of providing oversight regarding experimental design and methodology. - The level of commitment from the senior investigators appears appropriate to successfully complete the project. - The proposal brings together the knowledge of well established and experienced investigators who are in related fields and whose expertise with multiple assays are important to the successful completion of the proposed studies. Responsiveness to the RFA - The proposal is responsive in that it is essential to utilize human stem cells for this study since the virus is species specific. A weakness is that the emphasis of the study is on finding what stage of neuronal differentiation is altered (if any) rather than on uncovering mechanisms involved.