Amyotrophic Lateral Sclerosis (ALS) is a fatal motor neuron (MN) disease with astrocytes implicated as a significant contributor to MN death in familial ALS (fALS)1–5. However, these conclusions, in part, derive from rodent models of fALS based upon dominant mutations within the superoxide dismutase 1 (SOD1) gene which account for less than 2% of all ALS cases2, 4, 5. Here, we generated astrocytes from post-mortem tissue from both fALS and sporadic ALS (sALS) patients, and show that astrocytes derived from both patient groups are similarly toxic to MNs. In addition, we show that SOD1 is a viable target for sALS, as its knockdown significantly attenuates astrocyte-mediated toxicity towards MNs. Our data highlight astrocytes as a non-cell autonomous component in sALS and provide the first in vitro model system to investigate common disease mechanisms and evaluate potential therapies for sALS and fALS.

Respiratory viruses evolve to maintain infectivity levels that permit spread yet prevent host and virus extinction, resulting in surprisingly low infection rates. Respiratory viruses harnessed as gene therapy vectors have illustrated this limitation. We used directed evolution in an organotypic human airway model to generate a highly infectious adeno-associated virus. This virus mediated gene transfer more than 100-fold better than parental strains and corrected the cystic fibrosis epithelial Cl ؊ transport defect. Thus, under appropriate selective pressures, viruses can evolve to be more infectious than observed in nature, a finding that holds significant implications for designing vectors for gene therapy and for understanding emerging pathogens.

De novo mutations in the X-linked gene encoding the transcription factor methyl-CpG binding protein 2 (MECP2) are the most frequent cause of the neurological disorder Rett syndrome (RTT). Hemizygous males usually die of neonatal encephalopathy. Heterozygous females survive into adulthood but exhibit severe symptoms including microcephaly, loss of purposeful hand motions and speech, and motor abnormalities,whichappearafteraperiodofapparentlynormaldevelopment.Moststudieshavefocusedonmalemousemodelsbecauseoftheshorter latency to and severity in symptoms, yet how well these mice mimic the disease in affected females is not clear. Very few therapeutic treatments have been proposed for females, the more gender-appropriate model. Here, we show that self-complementary AAV9, bearing MeCP2 cDNA under control of a fragment of its own promoter (scAAV9/MeCP2), is capable of significantly stabilizing or reversing symptoms when administered systemically into female RTT mice. To our knowledge, this is the first potential gene therapy for females afflicted with RTT.

Stem cell-derived motor neurons (MNs) are increasingly utilized for modeling disease in vitro and for developing cellular replacement strategies for spinal cord injury and diseases such as spinal muscular atrophy (SMA) and amyotrophic lateral sclerosis (ALS). Human embryonic stem cell (hESC) differentiation into MNs, which involves retinoic acid (RA) and activation of the sonic hedgehog (SHH) pathway is inefficient and requires up to 60 days to develop MNs with electrophysiological properties. This prolonged differentiation process has hampered the use of hESCs, in particular for high-throughput screening. We evaluated the MN gene expression profile of RA/SHH-differentiated hESCs to identify rate-limiting factors involved in MN development. Based on this analysis, we developed an adenoviral gene delivery system encoding for MN inducing transcription factors: neurogenin 2 (Ngn2), islet-1 (Isl-1), and LIM/homeobox protein 3 (Lhx3). Strikingly, delivery of these factors induced functional MNs with mature electrophysiological properties, 11-days after gene delivery, with >60-70% efficiency from hESCs and human induced pluripotent stem cells (hiPSCs). This directed programming approach significantly reduces the time required to generate electrophysiologically-active MNs by approximately 30 days in comparison to conventional differentiation techniques. Our results further exemplify the potential to use transcriptional coding for rapid and efficient production of defined cell types from hESCs and hiPSCs.