Lentiviral vectors for treatment of haemophilia.
Doctoral thesis, UCL (University College London).
Haemophilia A and B are X‐linked recessive disorders caused by defects in coagulation factors (F) VIII and IX, respectively. Severe cases of haemophilia are characterised by episodes of spontaneous bleeding, predominantly into the joints and muscles, and can result in permanent disability and even mortality if left untreated. The haemophilias are compelling candidates for treatment with gene therapy as therapeutic benefit only requires a modest increase in the endogenous coagulation factor level, response to treatment can be easily monitored, and factor expression can be mediated by many cell types in vivo. Integration deficient lentiviral vectors (IDLVs) offer marked advantages over currently used integrating lentiviral vectors (ILVs) as side effects caused by insertional mutagenesis are potentially minimised. Previous work has shown that efficient and sustained transgene expression in non‐dividing cells, such as brain and muscle tissue, using IDLVs can be achieved. ILVs have previously been used to mediate long term expression of coagulation factors in vivo. In this study, we investigated the use of IDLVs as treatment for haemophilia with muscle and liver tissue (primarily nondividing hepatocytes) as principal targets. Transduction efficiency and relative transgene expression in vivo from ILVs and IDLVs were assessed in both tissues, and a number of strategies, including pseudotyping and tissue specific promoters, were utilised to improve targeted expression. Overall, despite achieving sustained transgene expression from IDLVs, in comparison to ILVs, the levels obtained were significantly lower and IDLVs were unable to mediate expression of human FIX at therapeutic levels in liver. Finally, the expression of bioengineered forms of human factor VIII (hFVIII) was assessed using ILVs in vivo after neonatal delivery. Long‐term expression was achieved and a 20‐fold increase in expression was observed after codon optimisation of the hFVIII cDNA sequence. In conclusion, IDLVs can mediate sustained transgene expression in vivo, however, vectors may need to be further optimised for increased expression to achieve clinical benefit for haemophilia patients.
|Title:||Lentiviral vectors for treatment of haemophilia|
|Open access status:||An open access version is available from UCL Discovery|
|UCL classification:||UCL > School of Life and Medical Sciences > Faculty of Population Health Sciences > Institute of Child Health > Department of Infection and Immunity > ICH - Molecular Immunology Unit|
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