Cell mediated gene therapy for muscular dystrophy: steps towards clinical efficacy.

This research aims to optimise a treatment that was recently tested in patients affected by Duchenne muscular dystrophy and extend it to another rare genetic diseases of the muscle, so that one strategy may in the future be adapted for more diseases.
Muscular dystrophies are caused by mutations in a single gene that leads to the impairment of function and death of muscles in the human body. This in turn causes disability of variable severity that, in the worse cases, are devastating; compromising quality of life and leading to a premature death. Although individual muscular dystrophies are rare or extremely rare, together they affect many thousands of people and represent a major challenge for National Health Services, in charge of providing palliative therapies and medical assistance, often over decades.
In order to "cure" genetic diseases it is necessary to replace or repair the defective gene and this can be achieved by using viral vectors (viruses that have been modified in the lab to deliver a correct version of the gene into cells) or stem cells (cells which can be used to generate any other type of cell in the body). To make sure they're accepted by the body, stem cells can be derived from a related donor (e.g. a sibling) or from the patient themselves, after having been "repaired" in the lab. These therapies have been successful so far for several genetic diseases affecting the blood, the skin, and the cornea. This has been possible because it is relatively easy to remove the diseased tissue and replace it. This approach is not possible for diseases affecting the heart, the liver or the brain. In these cases, healthy cells will have to correct the genetic defect and somehow help the function of the resident diseased cells.
The innovative aspect of our treatment is based on the fact that stem cells which are injected into the arteries of patients end up distributed uniformly throughout the body. Some of these stem cells can then cross out of the blood vessel, move into the surrounding tissue of the body and eventually repair it. However, the process is not yet efficient enough to result in a noticeable improvement in patients. In order to achieve this, we will study in detail each step of the transplantation procedure through a number of culture system using human stem cells. The successful completion of the research programme will rapidly lead to new clinical trials and then may be extended to more rare genetic diseases of muscle, increasing the benefit to patients.

This proposal aims to reach clinical efficacy with stem-cell mediated gene therapy for Muscular Dystrophies (MD). The PI completed a phase I/IIa trial based upon intra-arterial delivery of HLA-matched donor mesoangioblasts (Mabs), vessel-associated myogenic progenitors. Since these cells can cross the vessel wall in the presence of inflammation, they can be evenly distributed to downstream muscles, an essential condition for diffuse forms of MD. The trial was safe but not efficacious (especially in comparison with pre-clinical models) for a number of reasons such as the advanced stage of the disease in older patients, the moderate ability of stem cells to engraft and, consequently the need to produce the wt copy of the mutated gene also for the vast majority of resident cells. To address these issues, we will optimise each step of the transplantation protocol with human Mabs (adhesion to the endothelium, migration, fusion with regenerating fibres and finally over-production of the therapeutic gene product) with a number of in vitro assays that will allow to monitor dynamically and at the single cell level the behaviour of human Mabs. We will test different experimental strategies to enhance each of these processes in a fast and reliable way that will also allow to reduce animal experimentation only to these strategies that will have proven efficacious in vitro. Preliminary evidence indicate that at least binding to the endothelium and amplification of dystrophic production may be increased several fold thus strongly supporting feasibility. If successful, this project will set the basis for a rapid clinical translation of autologous, genetically corrected cells in younger dystrophic patients aiming at arresting or significantly delaying the progress of the disease.

The first beneficiaries of this programme will be patients affected by genetic, recessive, muscular dystrophies. In the future also patients affected by other rare genetic diseases of the mesoderm, may benefit from this therapeutic approach, if successful. It is important to stress that many recessive genetic diseases of the mesoderm are so rare that they will unlikely become the target of a specific research programme aimed at finding a possible therapy. The important added value of this project is a "one serves all" strategy, though of course adjustments will have to be made for each specific disease. However having available a common platform will dramatically cut time and costs for these patients that currently receive only palliative therapies and together present a major burden for the National Health System.
Patient associations may also benefit from this work and eventually decide to be involved in co-sponsoring further programmes and developments, as is already happening in the case of muscular dystrophy.
Beside Academic beneficiaries, students, training medical doctors, nurses and medical personnel in general may be involved and benefit for the future clinical translation of this therapeutic strategy. Moreover, although the programme is developed for rare disease that usually elicit a modest interest in companies, the possibility of applying intra-arterial delivery to MSC therapies that currently employ intra-venous injection, may significantly improve their efficacy and attract their interest, as most of these trials are sponsored by SME.
If successful this project should elicit the interest of policy-makers in the National Health Systems, both nationally and internationally for the possible adoption of new medical therapies, that, although associated with a very high cost, would lead, if successful to a dramatic reduction of the current costs related to long-term palliative treatments, medical, surgical and rehabilitation assistance. Last and most important, recovery of patient to at least partially normal and productive life will bear an additional advantage both in ethical and economic terms.