Duchenne muscular dystrophy (DMD) is a devastating incurable disease, affecting thousands with heavy burden on the health systems. This project combines the development of a safe, “immune-privileged cell” with genetic engineering to correct many dystrophin gene mutations for an efficacious and cost affordable therapy.
The applicant pioneered systemic intra-arterial transplantation of mesoangioblasts (blood vessel-derived progenitors) that proved safe in DMD patients and is being implemented for efficacy. However, this personalised approach would prove prohibitively expensive for healthcare systems, as pricing of successful gene therapies is showing. We made the striking observation that human mesoangioblasts can be indefinitely expanded with a novel culture medium, even after genetic manipulation and cloning.
In this project cells have been first genome edited to delete endogenous HLA (β2-microglubin and class II CTA) to make them invisible to the immune system while inserting the tolerogenic HLA-E, normally expressed by the placenta to prevent rejection of the foetus whose paternal antigens are "stranger" for the mother.
Selected clones will be engineered to express a small nuclear RNA (snRNA) that causes skipping of a given exon of the dystrophin gene. Due to the syncytial nature of muscle fibres, the snRNA also enters and corrects the genetic defect in neighbouring, dystrophic nuclei, thus amplifying of one log the therapeutic effect. Five different cell lines would correct the mutation in 60% of DMD patients.
The cell lines will be transplanted in humanized DMD mice and assessed for the ability to escape immune surveillance and to differentiate in dystrophin expressing myofibers, establishing pre-clinical safety and efficacy for an off the shelf, affordable product. The applicant has unique expertise to successfully complete this project, whose strategy may be expanded to other recessive monogenic diseases, for a ground breaking impact in regenerative medicine.
