Cell & Gene Therapy

The Cell and Gene Therapy Group are investigating possible ways of treating genetic disorders. One method involves gene therapy - introducing 'healthy' copies of genes into a patient's cells. This concept has proved harder to implement than previously thought. For example, the large size of most human genes has necessitated the use of 'stripped-down' versions of these genes. However, minimising the amount of genetic material used can exclude stretches of DNA that would normally control the gene's function.

Safer and more efficient ways of delivering these 'replacement' genes directly to their target cells need to be devised. Research is also required on how to keep the inserted DNA intact and retain its normal functions in the cell. There are serious concerns about the safety and effectiveness of gene therapy, and the team at Murdoch Childrens are committed to addressing these issues.

The group is also investigating treatments based on cell therapy, and the use of drugs to modify gene expression. In many genetic illnesses, it may even be possible to alter other genes pharmacologically so as to overcome the disease. The Cell and Gene Therapy team is developing a number of in vitro and in vivo model systems that can be used to identify and evaluate novel pharmacological agents that can alter the impacts of specific gene mutations which cause disease.

Group Leaders: 
Dr Bradley McColl
Role: 
Senior Research Officer
Dr Nicole Buck
Role: 
Research Officer
Betty Kao
Role: 
PhD Student
Astrid Glaser
Role: 
PhD Student
Tiwaporn Pualkaew
Role: 
PhD Student
Panjaree Siwaponanan
Role: 
PhD Student

Epigenetic modifications of the human β-globin locus: new therapeutic targets for haemoglobin disorders
Haemoglobin disorders, such as sickle cell disease and β-thalassaemia are the result of mutations in the adult β-globin gene. When these disorders are co-inherited with hereditary persistence of fetal haemoglobin, (high levels of γ-globin gene expression in adult life) the disease phenotype is much reduced. Therefore, understanding the mechanism of γ-globin globin gene regulation through development has been the subject of intense investigation for many years. These studies led to an appreciation of the role of epigenetic modifications such as DNA methylation and histone acetylation in globin gene expression and regulation. As a result, considerable efforts have been focused on the pharmacologic induction of fetal haemoglobin (HbF) using epigenetic-specific agents. This study will investigate the potential impact of epigenetic regulators on globin gene expression. Positive outcomes of such studies could pave the way for better treatment strategies for sickle cell anaemia and β-thalassaemia patients by targeting epigenetic regulators to increase fetal globin expression.

Site-specific integration of gene therapy vectors: Applications in Stem cells and gene therapy
One of the major obstacles to successful gene therapy is the random integration of the therapeutic transgene, which is associated with insertional mutagenesis and oncogenesis. Using specific elements derived from adeno-associated virus (AAV) the research group has developed a novel strategy to enhance the delivery, and site-specific integration of large DNA molecules into the human genome. Researchers have recently shown that we can enhance the delivery, and facilitate the site-specific integration of the entire human b-globin locus. This project will also investigate the site-specific integration of functional genomic loci into stem cells using CRISPR/TALEN strategies. Reporter gene expression and fluorescence in situ hybridisation will be used to monitor targeted integration and tissue-specific expression. It is proposed that this gene therapy strategy may be used in conjunction with patient-derived stem cells to facilitate persistent and stable transgene expression while avoiding the risks associated with random integration.

RNAi therapy: Applications in b-thalassaemia
b-Thalassaemia is an inherited haemoglobinopathy arising from mutated b-globin genes, resulting in reduced or absent b-globin synthesis. Much of the pathology is due to excess a-globin chains forming insoluble precipitates in erythroid cells resulting in cell death, ineffective erythropoiesis and severe anaemia. Decreased a-globin chain synthesis leads to milder symptoms, exemplified by individuals who co-inherit a- and b-thalassaemia. A possible therapeutic strategy in the treatment of b-thalassemia could include targeted reduction of a-globin chains to mimic co-inheritance of a/b-thalassemia.  RNA interference (RNAi) is an innovative new strategy for modulating gene expression and this pathway can potentially be exploited to mediate reductions in α-globin. Researchers have demonstrated that RNAi-mediated reduction of α-globin results in phenotypic improvements in β-thalassaemic cells. This project aims to develop novel gene therapy strategies for the reduction of α-globin expression in erythroid cells. Further studies will also be conducted using our unique b-thalassaemia mouse models and patient-derived cells.

How does thalassaemia affect resistance to bacterial pathogens?
Thalassaemia is one of the most common genetic disorders affecting haemoglobin synthesis. This results in severe anaemia that must be treated with regular blood transfusions every three-four weeks.  As a consequence of the frequent blood transfusions and excessive iron absorption, thalassaemia patients develop a state of iron overload resulting in damage and failure of the heart and/or liver. The second most frequent cause of mortality and morbidity in thalassaemia patients are infections. In particular, ferrophilic Gram-negative bacteria such as Klebsiella pneumoniae and Yersinia enterocolitica, are reported in patients undergoing iron chelation therapy.  Encapsulated bacteria, such as Streptococcus pneumoniae, cause serious infections in splenectomized patients. A large number of immune abnormalities have also been described, mostly due to iron overload and/or long-term receipt of multiple blood transfusions. In this project, researchers will use a mouse model for thalassaemia to investigate the deficiencies in the immune system that predispose to increased susceptibility to infection with bacterial pathogens S. pneumoniae, Salmonella typhimurium and/or K. pneumoniae.  The effect of immunodeficiencies in the thalassaemic mice on vaccination against these organisms will also be investigated.