Gwenaelle Geleoc, PhD
Rescue of Inner Function in Mouse Models of Usher Syndrome
Usher syndrome (USH) is a devastating incurable rare genetic disorder which leads to deafness and blindness. Three clinical subtypes have been described (type 1, 2 and 3). USH1 is the most severe form with profound deafness and balance deficits at birth and progressive vision loss leading to pre-pubertal blindness. USH1 includes a family of five genes that interact and play important functional roles in the sensory cells of the inner ear and the eye. One of the central players, USH1C encodes a protein called Harmonin, which is located in the sound and balance sensing structures of inner ear sensory cells. For this project I will begin to develop treatment strategies for Usher syndrome. I will use deaf and blind mice that carry that same harmonin mutation found in a large family of USH1C patients. Using a gene therapy approach, I propose to repair the sensory cells of the inner ear by introducing the correct DNA sequence for harmonin. Initially, I will examine the ability of the gene therapy approach to restore sound and balance sensitivity at the cellular level. If successful, I will introduce the gene therapeutics into live mice and attempt to restore hearing and balance function in deaf and dizzy mice.
Genri Kawahara, PhD
Therapeutic Drug Discovery using Fish Models of Muscular Dystrophies
The muscular dystrophies are a heterogeneous group of genetic disorders for which there are now emerging therapies. Despite these advances, there are only a few small molecules that can modify muscle disease. Zebrafish represent an excellent model in which to test for small molecules that can alter disease progression in a live organism. Our laboratory and collaborators have some excellent fish models of the human muscular dystrophies. Each fish has clear muscle phenotype due to a gene mutation in a muscle membrane protein, a muscle extracellular matrix and a muscle intracellular protein. 1) Sapje and sapje-like fish are the model fish of DMD with a mutation in the dystrophin gene 2) Dystroglycan deficient fish are a model fish for dystroglynopathies. Dystroglycan is a muscle membrane protein consisting of α- and β-dystroglycan, which interacts with dystrophin and extracellular laminin 3) Laminin α2 mutant fish are a model fish for congenital muscular dystrophy 1A (MDC1A). The laminin α2 gene is expressed in the basement membrane of skeletal muscle and has been shown to bind to α-dystroglycan. We have already successfully screened three libraries using two DMD model fish, sapje and sapje-like fish. Through this chemical screen, we have identified 14 candidates chemicals that demonstrated an ability to partly restore muscle to normal. The goal of this proposal is to test these potentially therapeutic small molecules already approved for use in humans to determine if any can ameliorate muscle degeneration in zebrafish models of human muscular dystrophy. We will also use each two additional model zebrafish to look for new small molecules which might be corrective.
Sung-Yun Pai, MD
Molecular and proteomic analysis of immune reconstitution after gene therapy for Wiskott-Aldrich
Wiskott-Aldrich syndrome (WAS) is a rare disease which affects boys from birth. The gene responsible for WAS causes defects in many different blood cell types. Boys with WAS suffer from low platelets predisposing them to life-threatening bleeding, immune problems predisposing them to serious infections, and autoimmune disease such as immune attack on blood cells, inflammatory bowel disease, and vasculitis. Because the blood cells are the only part of the body affected by WAS, the disease can be cured by bone marrow or other blood cell transplantation (also called hematopoietic cell transplantation or HCT). HCT is best performed a well matched donor, but many boys with WAS lack a well-matched donor. In addition, HCT can result in serious complications, such as graft-versus-host disease (GVHD), a syndrome in which the immune cells from the donor attack the patient’s body. As many as 25-50% of boys with WAS undergoing HCT will not survive. We have opened a gene therapy (GT) trial to treat 5 boys with WAS who lack a well-matched donor or have other high risk features. The patient’s own bone marrow will be treated with a specially engineered virus to insert the normal WAS gene into a part of the bone marrow cells. The “gene corrected” bone marrow cells are given back to the patient; in this way even a patient who doesn’t have a matched donor can have a transplant, using his own cells, and avoiding GVHD. While avoiding GVHD is a clear advantage of GT, GT could have disadvantages compared to allo-HCT. Because the virus can only correct a portion of the bone marrow cells, WAS patients after GT will inevitably have a mixture of normal and abnormal blood cells after the procedure, whereas most WAS patients after allo-HCT have 80-100% of donor-derived, normal blood cells. Whether a partial correction of blood cells will be enough to keep the WAS patient safe from life-threatening infection or autoimmunity is not known. We wish to take extra blood samples from the 5 patients to be enrolled on the WAS GT trial and use these to do detailed, cutting edge immune analysis, comparing to blood samples from 5 WAS allo-HCT patients. These studies will allow us to learn which blood cell types have improved number and function after GT as well as the quality and timing of that improvement. Ultimately we hope to understand whether GT is effective as a treatment compared to allo-HCT and why it is or is not.
David Williams, MD
Gene-therapy for Sickle Cells Anemia and Thalassemia: A Translational Study
Disorders caused by abnormal hemoglobin, the protein responsible for oxygen transport in the body, represent a major health challenge. In fact, humans with disorders like sickle cell anemia suffer from considerable reduction in their quality of life and global life expectancy. Currently, no cure exists for patients with these disorders outside of bone marrow transplantation, which can cause severe side-effects and is responsible for a high mortality risk. With our study, we will investigate whether we can increase the presence of fetal hemoglobin (called gamma-globin), which usually is present in prenatal life, and decrease the abnormal hemoglobin concentration by acting on a protein called BCL11A. This protein has been involved in the switching from the prenatal (gamma-) globin to adult-life (beta-) globin. We will influence BCL11A levels by using gene therapy. We seek to determine whether this intervention causes the desired globin switch without significant toxicity to cells. Gene-therapy could be an innovative way to cure children and adults with abnormal hemoglobins, and constitute a model for other rare and orphan diseases.