Producing hiPS cells for disease modeling of NLSD-M

NLSD-M (Neutral Lipid Storage Disease with Myopathy) is a rare autosomal recessive disorder characterized by an abnormal intracellular accumulation of triacylglycerol into cytoplasmic lipid droplets (LDs). In most tissues the lipid droplets (LDs) are cellular organelles for the triacylglycerol storage. LDs metabolic functions are mediated by proteins bound to their surface. In particular, the lipase that catalyzes the removal of the first acyl chain from triacylglycerol is the patatin-like phospholipase domain-containing protein 2 (PNPLA2). This protein is coded by the PNPLA2 gene whose mutations cause the onset of Neutral Lipid Storage Disease with Myopathy. NLSD-M patients are affected by progressive myopathy, cardiomyopathy and hepatomegaly. Other clinical symptoms may include diabetes, chronic pancreatitis and short stature. NLSD-M has, at present, no specific therapy. We have previously reported clinical and genetic findings of some NLSD-M patients obtaining dermal biopsies from them. Here we report the development of hiPSc (human induced pluripotent stem cell) from patients’ fibroblasts harboring different PNPLA2 mutations. Initial hiPSc colony selection was based on morphologic evaluation and on detection of pluripotency surface markers (SSEA-4 and TRA-1-81). HiPSc also expressed undifferentiated ES cell markers (NANOG, SOX2 and OCT4). Karyotypic analysis of hiPSc lines indicated a normal complement of chromosomes. Immunohystochemical evaluations of LDs on hiPSc revealed that they recapitulate pathological hallmark of the disease. We propose use of differentiated cells derived from hiPSc to study the pathogenetic mechanisms leading to NLSD-M and as a cellular model for therapeutic evaluation.