Success of gene therapy
(i) Cell types capable of dividing in vitro (e.g. myeloblasts, hepatocytes, keratinocytes, endothelial cells, etc.) are amenable for in vitro and in vivo gene therapy, both the in vivo methods are preferred for cell types such as neuronal cells.
(ii) The function of gene products also govern the selection of tissues, for example in case of haemophilia a gene can be delivered in any tissue provided the gene product is released into blood stream. In addition, in case of cystic fibrosis the gene should be delivered to specific cell types where introduction of correct gene is required.
(iii) Another attractive strategy for the treatment of several disorders is antisense gene transfer, for example in b-thalassemia, a-globin chains are accumulated in RBCs that result in their premature decay. Such types of destruction can be prevented by infection of K562 erythroleukemia cells with AAV expressing human a-globin gene in antisense orientation.
Disease |
Gene inserted |
Cell types |
Remark |
ADA defficient SCID |
ADA-gene |
Peripheral T-lymphocytes and bone marrow cells |
Repeated injections to be given |
Duchenne's muscular dystrophy |
Dystrophin gene |
Myoblasts |
Trials in USA |
Haemophilia B |
Factor IX |
Autologous skin fibroblast |
Trials in China |
Cystis fibrosis |
CFTR gene |
- |
Gene delivery to lung cells via liposomes |