Project description:Pompe disease (glycogen storage disease type II, or acid maltase deficiency) is an autosomal-recessive disorder of metabolism caused by mutations in the lysosomal hydrolase, acid alpha-glucosidase gene (GAA), resulting in progressive muscle atrophy. The current standard of care treatment, enzyme replacement therapy, consists of delivering recombinant human GAA (rhGAA) to reduce muscle glycogen and improve patient quality of life. With the aim of developing in vitro systems to study human disease and test therapies, we applied RNA sequencing to 3D tissue-engineered human skeletal muscle to compare healthy, (infantile onset) Pompe disease, and rhGAA-treated Pompe engineered tissues.
Project description:Pompe disease is a genetic disorder resulting from a deficiency of lysosomal acid alpha-glucosidase (GAA) that manifests as a clinical spectrum with regard to symptom severity and rate of progression. In this study, we used microarrays to examine gene expression from the muscle of two cohorts of infantile-onset Pompe patients to identify transcriptional differences that may contribute to the disease phenotype. We found strong similarities among the gene expression profiles generated from biceps and quadriceps, and identified a number of signaling pathways altered in both cohorts. We also found that infantile-onset Pompe patient muscle had a gene expression pattern characteristic of immature or regenerating muscle, and exhibited many transcriptional markers of inflammation, despite having few overt signs of inflammatory infiltrate. Further, we identified genes exhibiting correlation between expression at baseline and response to therapy. This combined dataset can serve as a foundation for biological discovery and biomarker development to improve the treatment of Pompe disease.
Project description:Pompe disease (glycogen storage disease type II, or acid maltase deficiency) is an autosomal-recessive disorder of metabolism caused by mutations in the lysosomal hydrolase, acid alpha-glucosidase gene (GAA), resulting in progressive muscle atrophy. Gene therapy is a promising approach to treat genetic diseases, and liver-restricted expression of secretable GAA can produce immune tolerance and improve muscle GAA activity. To further understand the molecular mechanisms underlying Pompe disease and impact of gene therapy, we applied RNA sequencing.
Project description:Pompe disease is a neuromuscular disorder caused by mutations in the gene encoding for the lysosomal enzyme acid α-glucosidase (GAA). GAA converts lysosomal glycogen to glucose, and its deficiency leads to pathologic glycogen accumulation. Enzyme replacement therapy (ERT) is the only available treatment for Pompe disease at the moment with several shortcomings. We have shown that liver expression of secGAA has better therapeutic efficacy than non-engineered GAA after long-term treatment of four months old Gaa-/- mice with low vector doses. Based on those results, we have treated severely affected nine months old Gaa-/- mice with the AAV-secGAA vector and followed the animals for nine months thereafter. At the end of the study, AAV-treated Gaa-/- mice showed complete rescue of the Pompe phenotype. Transcriptomic profiling of skeletal muscle highlighted mitochondrial bioenergetics defects, supported by electron microscopy, western blotting and biochemical findings, which were partially corrected after AAV treatment. Together, these results provide insight into the reversibility of advanced Pompe disease in the Gaa-/- mouse model via liver gene transfer of secGAA.
Project description:<p>Infantile-onset Pompe disease is an inherited disorder that is normally diagnosed within the first months of life. It is caused by lack of or defect in an enzyme (a special protein that carries out normal chemical reactions within the body) called acid alpha-glucosidase (GAA). GAA normally breaks down glycogen (stored sugar) in lysosomes (the part of the cell that digests food and other chemicals). Pompe disease is one of many lysosomal storage diseases (LSDs). LSDs are diseases caused by the malfunction of the lysosome or one of their digestive enzymes. Patients with Pompe disease cannot break down lysosomal glycogen. This causes glycogen to build up and damage cells throughout the body, especially in the heart and muscles.</p> <p>Current treatment for Pompe disease involves enzyme replacement therapy (ERT). In this treatment, the drug alglucosidase alfa (Myozyme) is put into your blood. The drug provides a form of the GAA enzyme to replace the enzyme that is missing or not working properly in the patient's blood. This treatment has allowed babies to live longer and achieve developmental milestones.</p> <p>In this study, researchers will learn about the patient's ability to tolerate ERT. Cross-Reactive Immunological Material (CRIM) is a measurement of natural GAA production. A patient's CRIM status (either positive or negative) is an important factor that affects how he or she responds to ERT with Myozyme. Children who produce some natural GAA are classified as CRIM+, while children who do not produce any natural GAA are classified as CRIM-.</p> <p>Children who are CRIM+ generally tolerate ERT well. But, children who are CRIM-, and some children classified as CRIM+, have a poor response to ERT. Patients who have a poor response to ERT have complications because their body sees Myozyme as "foreign" and triggers an immune response to try to remove it from the body. Treatments are currently being developed to stop this immune response and prevent complications from ERT.</p> <p>We will enroll patients with Infantile Pompe disease in this longitudinal natural history (observational) study. The specific aims of this study are: <ol> <li>To determine and correlate Cross-Reactive Immunological Material (CRIM) status with the GAA gene mutations found on these patients</li> <li>To validate an approach for determining CRIM status from whole blood sample, with the gold standard determination of CRIM status by skin fibroblasts and mutation analysis</li> <li>To explore the clinical treatment response and natural history of CRIM-positive and CRIM-negative Pompe disease patients with and without immune modulation</li> <li>To investigate the role of immune response to treatment</li> </ol> </p>
Project description:Pompe disease is a Lysosomal glycogen storage disorder due to the deficiency of acid alpha glucosidase. The enzyme degrades glycogen to glucose and its deficiency results in progressive enlargement of glycogen-filled lysosomes in multiple tissues with skeletal and cardiac muscle most severely affected clinically. Clinical spectrum ranges from most severe infantile cardiomegally and skeletal muscle myopathy to milder late onset forms with only skeletal muscle pathology. The currently available enzyme replacement therapy has only limited effect in skeletal muscle. Here we use RNA sequencing of therapy-resistant skeletal muscle (white part of gastrocnemius muscle) to identify the differencies between the diseased and healthy muscle. Total RNA was obtained from gastrocnemius muscle (white part) of acid alpha glucosidase knock-out and wild-type mice.
Project description:While there are many human skeletal muscle disorders, very few therapies have been developed. It has not been possible to generate large amounts of purified skeletal muscle cells from pluripotent stem cells, and to test therapies quantitatively. We therefore devised conditions for generating and expanding purified human myogenic progenitors from induced pluripotent stem (iPS) cells. The progenitors retained the capacity to differentiate into multinucleated myotubes and showed a normal karyotype throughout the expansion phase. We applied this method to Pompe disease, a metabolic myopathy caused by deficiency of the lysosomal enzyme acid alpha-glucosidase (GAA). In a screen, we identified sequences that suppressed aberrant GAA exon 2 splicing caused by the frequent c.-32-13T>G (IVS1) GAA variant. Antisense oligonucleotides (AONs) that blocked these sequences promoted exon 2 inclusion in patient-derived myotubes. As this raised GAA enzymatic activity above the disease threshold, AON-mediated splicing correction may provide a treatment option for Pompe disease.
Project description:Pompe disease (PD) is a neuromuscular disorder caused by deficiency of acid-alpha-glucosidase (GAA), leading to motor and respiratory dysfunctions. Available Gaa knock-out (KO) mouse models do not accurately mimic PD, particularly the highly impaired respiratory phenotype. Methods. Here we developed a new mouse model of PD crossing Gaa KO B6;129 with DBA2/J mice. Findings. Male Gaa KODBA2/J presents most of the key features of the human disease, including early lethality, severe respiratory impairment, cardiac hypertrophy and muscle weakness. Transcriptome analyses of Gaa KODBA2/J, compared to the parental Gaa KOB6;129 mice, revealed a profoundly impaired gene signature in the spinal cord and a similarly deregulated gene expression in skeletal muscle. Muscle and spinal cord transcriptome changes in Gaa KODBA2/J, were significantly improved upon gene therapy with AAV vectors expressing a secreted GAA enzyme.