Treatment algorithm for infants diagnosed with spinal muscular atrophy through newborn screening

Spinal muscular atrophy (SMA) is an autosomal recessive disease characterized by the degeneration of alpha motor neurons in the spinal cord, leading to muscular atrophy. SMA is caused by deletions or mutations in the survival motor neuron 1 gene (SMN1). In humans, a nearly identical copy gene, SMN2, is present. Because SMN2 has been shown to decrease disease severity in a dose-dependent manner, SMN2 copy number is predictive of disease severity. To develop a treatment algorithm for SMA-positive infants identified through newborn screening based upon SMN2 copy number. A working group comprised of 15 SMA experts participated in a modified Delphi process, moderated by a neutral third-party expert, to develop treatment guidelines. The overarching recommendation is that all infants with two or three copies of SMN2 should receive immediate treatment (n = 13). For those infants in which immediate treatment is not recommended, guidelines were developed that outline the timing and appropriate screens and tests to be used to determine the timing of treatment initiation. The identification SMA affected infants via newborn screening presents an unprecedented opportunity for achievement of maximal therapeutic benefit through the administration of treatment pre-symptomatically. The recommendations provided here are intended to help formulate treatment guidelines for infants who test positive during the newborn screening process

Generation of GFAP::GFP astrocyte reporter lines from human adult fibroblast-derived iPS cells using zinc-finger nuclease technology

Astrocytes are instrumental to major brain functions, including metabolic support, extracellular ion regulation, the shaping of excitatory signaling events and maintenance of synaptic glutamate homeostasis. Astrocyte dysfunction contributes to numerous developmental, psychiatric and neurodegenerative disorders. The generation of adult human fibroblast-derived induced pluripotent stem cells (iPSCs) has provided novel opportunities to study mechanisms of astrocyte dysfunction in human-derived cells. To overcome the difficulties of cell type heterogeneity during the differentiation process from iPSCs to astroglial cells (iPS astrocytes), we generated homogenous populations of iPS astrocytes using zinc-finger nuclease (ZFN) technology. Enhanced green fluorescent protein (eGFP) driven by the astrocyte-specific glial fibrillary acidic protein (GFAP) promoter was inserted into the safe harbor adeno-associated virus integration site 1 (AAVS1) locus in disease and control-derived iPSCs. Astrocyte populations were enriched using Fluorescence Activated Cell Sorting (FACS) and after enrichment more than 99% of iPS astrocytes expressed mature astrocyte markers including GFAP, S100β, NFIA and ALDH1L1. In addition, mature pure GFP-iPS astrocytes exhibited a well-described functional astrocytic activity in vitro characterized by neuron-dependent regulation of glutamate transporters to regulate extracellular glutamate concentrations. Engraftment of GFP-iPS astrocytes into rat spinal cord grey matter confirmed in vivo cell survival and continued astrocytic maturation. In conclusion, the generation of GFAP::GFP-iPS astrocytes provides a powerful in vitro and in vivo tool for studying astrocyte biology and astrocyte-driven disease pathogenesis and therapy

Gene Profiling of Human Induced Pluripotent Stem Cell-Derived Astrocyte Progenitors Following Spinal Cord Engraftment.

The generation of human induced pluripotent stem cells (hiPSCs) represents an exciting advancement with promise for stem cell transplantation therapies as well as for neurological disease modeling. Based on the emerging roles for astrocytes in neurological disorders, we investigated whether hiPSC-derived astrocyte progenitors could be engrafted to the rodent spinal cord and how the characteristics of these cells changed between in vitro culture and after transplantation to the in vivo spinal cord environment. Our results show that human embryonic stem cell- and hiPSC-derived astrocyte progenitors survive long-term after spinal cord engraftment and differentiate to astrocytes in vivo with few cells from other lineages present. Gene profiling of the transplanted cells demonstrates the astrocyte progenitors continue to mature in vivo and upregulate a variety of astrocyte-specific genes. Given this mature astrocyte gene profile, this work highlights hiPSCs as a tool to investigate disease-related astrocyte biology using in vivo disease modeling with significant implications for human neurological diseases currently lacking animal models

Maximizing the Benefit of Life-Saving Treatments for Pompe Disease, Spinal Muscular Atrophy, and Duchenne Muscular Dystrophy Through Newborn Screening: Essential Steps

Newborn screening (NBS) identifies infants with specific congenital disorders for which earlier intervention cannot only prevent a lifetime of chronic disability but also, most importantly, save lives. In this article, we discuss complexities associated with NBS processes in the United States, with a focus on challenges in neuromuscular disorders. As new interventions for neuromuscular disorders become available, the clinical community must prepare to overcome the challenges of adding new diseases to screening panels and understand the rigorous evidence review at the federal level and the complex process of state-level implementation. In this regard, NBS programs for Pompe disease and spinal muscular atrophy can guide the path of Duchenne muscular dystrophy and other neuromuscular disorders as future candidates for NBS. The availability of advanced screening methods, the emergence of effective treatment, and the support of professional organizations may facilitate the expansion of NBS, such that an increasing number of infants can be identified in the newborn period who will benefit from life-saving interventions