[P3-110] Method of evaluating survival motor neuron protein as an outcome measure of SMA-modifying therapy
Background: Spinal muscular atrophy (SMA) is a severe genetic neurodegenerative disorder caused by survival motor neuron (SMN) protein deficiency in motor neurons, which leads to progressive muscle weakness. A major goal of SMA-modifying therapy is to increase SMN expression. We investigated whether imaging flow cytometry (IFC) can serve a viable source of quantitative information on the SMN protein as an outcome measure of SMA therapy.
Materials and methods: Fibroblasts, lymphoblasts and peripheral blood cells were collected from 14 SMA patients and 16 healthy control subjects. The cells were stained with a mouse monoclonal anti-SMN antibody and analyzed with IFC. IFC demonstrated accumulation, localization, and expression of SMN protein, detected by a digital microscope system and immunological technologies.
Results: SMN expression was significantly decreased in fibroblasts, lymphoblasts and peripheral blood cells from patients relative to those from healthy control subjects (p<0.05). Moreover, SMN expression correlated with the clinical severity of SMA according to SMN2 copy number in lymphoblasts and peripheral blood cells. After sorting blood cell populations by surface antigens, IFC identified differences in SMN protein expressions in the T cell, B cell, and monocyte fractions between patients and controls.
Conclusions: We developed a method of SMN protein evaluation using IFC. The data obtained with this method of analyzing SMN protein in peripheral blood cells can be applied as an outcome measure in multicenter cooperative and investigator-initiated clinical trial using valproic acid in childhood onset SMA in Japan.
Materials and methods: Fibroblasts, lymphoblasts and peripheral blood cells were collected from 14 SMA patients and 16 healthy control subjects. The cells were stained with a mouse monoclonal anti-SMN antibody and analyzed with IFC. IFC demonstrated accumulation, localization, and expression of SMN protein, detected by a digital microscope system and immunological technologies.
Results: SMN expression was significantly decreased in fibroblasts, lymphoblasts and peripheral blood cells from patients relative to those from healthy control subjects (p<0.05). Moreover, SMN expression correlated with the clinical severity of SMA according to SMN2 copy number in lymphoblasts and peripheral blood cells. After sorting blood cell populations by surface antigens, IFC identified differences in SMN protein expressions in the T cell, B cell, and monocyte fractions between patients and controls.
Conclusions: We developed a method of SMN protein evaluation using IFC. The data obtained with this method of analyzing SMN protein in peripheral blood cells can be applied as an outcome measure in multicenter cooperative and investigator-initiated clinical trial using valproic acid in childhood onset SMA in Japan.