Exploring the microvascular abnormalities in a cohort of paediatric patients with spinal muscular atrophy: P.51

Microvascular abnormalities have been described in transgenic SMN deficient mice models as well as in severe SMA patients. Alterations in specific vascular-related factors have been also recently reported in patients. The aim of this ongoing research is to study markers of endothelial injury (circulating endothelial cells) and endothelial repair by isolation of endothelial progenitor cells (EPC), together with the expression of angiogenic factors in patients. We are also exploring the possibility of detecting microvascular abnormalities in peripheral organs easily accessible in patients such as the retina and nail fold beds to determine if these can provide information on integrity of the vascular system. The retinal imaging for vascular mapping is carried out using an OPTOS scanning laser ophtalmoscope camera able to capture ultra wide field (200 degree) images of the fundus visualising blood vessels from the optic nerve to the peripheral retina. A high resolution Optilia portable capillaroscopy system is used to capture images of the nail fold capillary beds in the fingers of patients. Parameters under evaluation are: capillary appearance, dimension, density and presence of extravasation/micro-haemorrhages. Eight patients have been recruited so far: 4 with SMA II and 4 with SMA III. In 7/8 peripheral blood sampling was also obtained to isolate EPC to perform an angiogenic factors microarray assay and angiogenic and endothelial injury markers. We have so far studied the retina in one patient with SMA 3 and conducted the nail fold capillaroscopy in one patient with SMA 2; in both cases images were obtained for analysis and the techniques were well tolerated. This study will help to address the characterisation of the microvasculature in SMA patients as well as provide information on potentially new non-invasive biomarkers.