The results of a clinical trial have shown that transplanting cells from unaffected muscles into the throat may help with the swallowing difficulties that affect people with oculopharyngeal muscular dystrophy (OPMD).
OPMD is a rare type of muscular dystrophy which is unusual because it primarily affects two small muscle groups – the pharyngeal muscles used for swallowing and the muscles around the eyes. Swallowing difficulties have a major impact on quality of life and can be fatal due to severe weight loss and aspiration pneumonia (lower respiratory tract infection due to inhalation of food and saliva).
Since the other muscles of the body are generally spared from muscle weakness in OPMD, a clinical trial was embarked on in Paris, France to transplant these cells into the throat. Twelve people with OPMD were enrolled into the study and a biopsy was taken either from their neck (sternocleidomastoid muscle) or upper thigh (quadriceps). This muscle sample was sent to a laboratory where cells called myoblasts – which have the ability to develop into muscle fibres – were isolated and grown until there were enough cells for the transplant. The patients then underwent an operation called a “cricopharyngeal myotomy”. OPMD patients often have this procedure to release contracted scar tissue in the throat and improve swallowing. During this procedure the trial participants also had their own myoblasts injected into the pharynx.
The trial participants were followed up for two years after the transplant and it was found that swallowing improved for all twelve participants and remained stable. Longer term follow-up is also ongoing and the results appear to be positive, whereas people with OPMD who only have the cricopharyngeal myotomy surgery generally initially improve but then deteriorate. The procedure was also well tolerated which is encouraging news for people with OPMD.
However, it must be remembered that this was only a small trial and due to the rarity of the condition it was not feasible to include a placebo group for comparison – that is, patients who did not receive the myoblast injections. Valuable information on the best way to perform the transplant was gained in this study which will be used to plan a larger trial to assess in more detail the benefit of myoblast transplantation for OPMD before it can be brought into clinical practice.
It also must be noted that the transplanted cells contain the genetic mutation that causes OPMD so it is expected that these will also eventually succumb to the condition, but since it is a late onset condition that progresses slowly it is hoped that this might still be a viable treatment option.
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This research was published in the journal Molecular Therapy and is freely available by clicking on the link below. The article is written in technical language with no summary in lay terms:
Périé S, Trollet C, Mouly V, Vanneaux V, Mamchaoui K, Bouazza B, Marolleau JP, Laforêt P, Chapon F, Eymard B, Butler-Browne G, Larghero J, St Guily JL. Autologous myoblast transplantation for oculopharyngeal muscular dystrophy: a phase i/iia clinical study. Mol Ther. 2014 Jan;22(1):219-25.