[Developments in gene delivery vectors for ocular gene therapy]

La thérapie génique des rétinites pigmentaires héréditaires

Les rétinites pigmentaires, ou dystrophies rétiniennes héréditaires, sont des maladies dégénératives cécitantes d’origine génétique. La thérapie génique est une approche révolutionnaire en plein essor qui ouvre la voie au traitement de maladies jusqu’ici incurables. Une thérapie génique, le Luxturna®, a obtenu une autorisation de mise sur le marché par la FDA (Food and Drug Administration) fin 2017 et l’EMA (European Medicines Agency) fin 2018. Ce traitement, à l’efficacité démontrée, destiné aux patients porteurs d’une amaurose congénitale de Leber ou d’une rétinopathie pigmentaire en lien avec une mutation bi-allélique du gène RPE65, apporte beaucoup plus de questions que de réponses. Nous présentons, dans cette revue, les avancées actuelles, puis les défis technologiques, économiques et éthiques à surmonter pour que la thérapie génique améliore nos pratiques médicales.

[Gene therapy progress: hopes for Usher syndrome]

Hearing and balance impairment are major concerns and a serious public health burden, as it affects millions of people worldwide, but still lacks an effective curative therapy. Recent breakthroughs in preclinical and clinical studies using viral gene therapy suggest that such an approach might succeed in curing many genetic diseases. Our actual understanding and the comprehensive analysis of the molecular bases of genetic deafness forms have provided the multiple bridges toward gene therapy to correct, replace, or modify the expression of defective endogenous genes involved in deafness. The aim of this review article is to summarize the recent advances in the restoration of cochlear and vestibular functions by local gene therapy in mouse models of Usher syndrome, the leading genetic cause of deafness associated with blindness in the world. We focus herein on therapeutic approaches with the highest potential for clinical application.

Evolving lessons on nanomaterial-coated viral vectors for local and systemic gene therapy

Viral vectors are promising gene carriers for cancer therapy. However, virus-mediated gene therapies have demonstrated insufficient therapeutic efficacy in clinical trials due to rapid dissemination to nontarget tissues and to the immunogenicity of viral vectors, resulting in poor retention at the disease locus and induction of adverse inflammatory responses in patients. Further, the limited tropism of viral vectors prevents efficient gene delivery to target tissues. In this regard, modification of the viral surface with nanomaterials is a promising strategy to augment vector accumulation at the target tissue, circumvent the host immune response, and avoid nonspecific interactions with the reticuloendothelial system or serum complement. In the present review, we discuss various chemical modification strategies to enhance the therapeutic efficacy of viral vectors delivered either locally or systemically. We conclude by highlighting the salient features of various nanomaterial-coated viral vectors and their prospects and directions for future research.

Developing a Novel Gene-Delivery Vector System Using the Recombinant Fusion Protein of Pseudomonas Exotoxin A and Hyperthermophilic Archaeal Histone HPhA

Non-viral gene delivery system with many advantages has a great potential for the future of gene therapy. One inherent obstacle of such approach is the uptake by endocytosis into vesicular compartments. Receptor-mediated gene delivery method holds promise to overcome this obstacle. In this study, we developed a receptor-mediated gene delivery system based on a combination of the Pseudomonas exotoxin A (PE), which has a receptor binding and membrane translocation domain, and the hyperthermophilic archaeal histone (HPhA), which has the DNA binding ability. First, we constructed and expressed the rPE-HPhA fusion protein. We then examined the cytotoxicity and the DNA binding ability of rPE-HPhA. We further assessed the efficiency of transfection of the pEGF-C1 plasmid DNA to CHO cells by the rPE-HPhA system, in comparison to the cationic liposome method. The results showed that the transfection efficiency of rPE-HPhA was higher than that of cationic liposomes. In addition, the rPE-HPhA gene delivery system is non-specific to DNA sequence, topology or targeted cell type. Thus, the rPE-HPhA system can be used for delivering genes of interest into mammalian cells and has great potential to be applied for gene therapy.