M. Valadares

Ringo, a Golden Retriever Muscular Dystrophy (GRMD) dog with absent dystrophin but normal strength

The closest model to human Duchenne Muscular Dystrophy (DMD) is the Golden Retriever Muscular Dystrophy (GRMD) dog, which carries a point mutation in the splice acceptor site in intron 6 of the orthologe X-linked dystrophin gene, leading to the absence of protein in the muscles. These dogs present clinical signs within the first weeks of life involving the limbs as well as masticatory muscles. Diaphragmatic and intercostal muscles impairment leads to progressive respiratory failure. Death occurs from bronchopneumonia and cardiac arrest, usually before 2 years of age. Here, we report the case of Ringo, an exceptional GRMD dog showing an unusually mild course. Currently, at age 4 years and 10 months he is able to run, jump and open doors while standing on his rear paws. He was also able to breed naturally, which apparently has never been reported before. Ringo is descendant of Beth, a GRMD female carrier donated by Dr. Joe Kornegay (University of North Carolina, USA), and all affected descendants carry the same original mutation. The diagnosis in all dogs was established right after birth through DNA genotyping and elevated serum creatine kinase (CK). At birth, Ringo’s serum CK level was increased 10-fold as compared to his three normal sibs. One affected brother had a comparable serum CK while the other had a 20-fold increase. At 15 days serum CK in the affected dogs was 4to 5-fold higher than in normal siblings. Pedigree analysis (Fig. 1) revealed that Ringo had two affected brothers from the same litter. One of them died at 2 weeks of age. The other one is still alive but with a

Ringo: Discordance between the molecular and clinical manifestation in a Golden Retriever Muscular Dystrophy dog

Of the various genetic homologues to Duchenne Muscular Dystrophy (DMD), the Golden Retriever Muscular Dystrophy (GRMD) dog, which presents a variable but usually severe and progressive muscle weakness, has the closest relevance to DMD in both clinical severity and histopathological change. Among 77 GRMD dogs born in our colony in Brazil, we have identified a very mildly affected dog, Ringo, born July 2003. Among his descendants, at least one male, Suflair, is also showing a mild course. In an attempt to better characterize these two dogs, we studied the pattern of muscle proteins expression in Ringo and Suflair, as compared to severely affected and normal control dogs. Dystrophin was absent in both and utrophin was overexpressed in a pattern similar to the observed in severely affected dogs. Understanding the mechanism that is protecting Ringo and Suflair from the deleterious effect of the dystrophin gene mutation is of utmost interest. In addition it points out that the clinical impact of therapeutic trials should be interpreted with caution.

Human adipose-derived mesenchymal stromal cells injected systemically into GRMD dogs without immunosuppression are able to reach the host muscle and express human dystrophin.

Duchenne muscular dystrophy (DMD), a lethal X-linked disorder, is the most common and severe form of muscular dystrophies, affecting 1 in 3,500 male births. Mutations in the DMD gene lead to the absence of muscle dystrophin and a progressive degeneration of skeletal muscle. The possibility to treat DMD through cell therapy has been widely investigated. We have previously shown that human adipose-derived stromal cells (hASCs) injected systemically in SJL mice are able to reach and engraft in the host muscle, express human muscle proteins, and ameliorate the functional performance of injected animals without any immunosuppression. However, before starting clinical trials in humans many questions still need to be addressed in preclinical studies, in particular in larger animal models, when available. The best animal model to address these questions is the golden retriever muscular dystrophy (GRMD) dog that reproduces the full spectrum of human DMD. Affected animals carry a mutation that predicts a premature termination codon in exon 8 and a peptide that is 5% the size of normal dystrophin. These dogs present clinical signs within the first weeks and most of them do not survive beyond age two. Here we show the results of local and intravenous injections of hASCs into GRMD dogs, without immunosuppression. We observed that hASCs injected systemically into the dog cephalic vein are able to reach, engraft, and express human dystrophin in the host GRMD dystrophic muscle up to 6 months after transplantation. Most importantly, we demonstrated that injecting a huge quantity of human mesenchymal cells in a large-animal model, without immunosuppression, is a safe procedure, which may have important applications for future therapy in patients with different forms of muscular dystrophies.

A multi-exonic SPG4 duplication underlies sex-dependent penetrance of hereditary spastic paraplegia in a large Brazilian pedigree

SPG4 mutations are the most frequent cause of autosomal-dominant hereditary spastic paraplegia (HSP). SPG4 HSP is characterized by large inter- and intrafamilial variability in age at onset (AAO) and disease severity. The broad spectrum of SPG4 mutations has recently been further extended by the finding of large genomic deletions in SPG4-linked pedigrees negative for ‘small’ mutations. We had previously reported a very large pedigree, linked to the SPG4 locus with many affected members, which showed gender difference in clinical manifestation. Screening for copy number aberrations revealed the first case of a multi-exonic duplication (exon10_12dup) in the SPG4 gene. The mutation leads to a premature stop codon, suggesting that the protein product is not functional. The analysis of 30 individuals who carry the mutation showed that males have on average an earlier AAO and are more severely affected. The present family suggests that this HSP pathogenesis may be modulated by factors related to individual background and gender as observed for other autosomal dominant conditions, such as facio-scapulohumeral muscular dystrophy or amyloidosis. Understanding why some individuals, particularly women, are ‘partially protected’ from the effects of this and other pathogenic mutations is of utmost importance.

Preclinical Studies with Umbilical Cord Mesenchymal Stromal Cells in Different Animal Models for Muscular Dystrophy

Umbilical cord mesenchymal stromal cells (MSC) have been widely investigated for cell-based therapy studies as an alternative source to bone marrow transplantation. Umbilical cord tissue is a rich source of MSCs with potential to derivate at least muscle, cartilage, fat, and bone cells in vitro. The possibility to replace the defective muscle cells using cell therapy is a promising approach for the treatment of progressive muscular dystrophies (PMDs), independently of the specific gene mutation. Therefore, preclinical studies in different models of muscular dystrophies are of utmost importance. The main objective of the present study is to evaluate if umbilical cord MSCs have the potential to reach and differentiate into muscle cells in vivo in two animal models of PMDs. In order to address this question we injected (1) human umbilical cord tissue (hUCT) MSCs into the caudal vein of SJL mice; (2) hUCT and canine umbilical cord vein (cUCV) MSCs intra-arterially in GRMD dogs. Our results here reported support the safety of the procedure and indicate that the injected cells could engraft in the host muscle in both animal models but could not differentiate into muscle cells. These observations may provide important information aiming future therapy for muscular dystrophies.

Pericytes Extend Survival of ALS SOD1 Mice and Induce the Expression of Antioxidant Enzymes in the Murine Model and in IPSCs Derived Neuronal Cells from an ALS Patient

AbstractAmyotrophic Lateral Sclerosis (ALS) is one of the most common adult-onset motor neuron disease causing a progressive, rapid and irreversible degeneration of motor neurons in the cortex, brain stem and spinal cord. No effective treatment is available and cell therapy clinical trials are currently being tested in ALS affected patients. It is well known that in ALS patients, approximately 50% of pericytes from the spinal cord barrier are lost. In the central nervous system, pericytes act in the formation and maintenance of the blood-brain barrier, a natural defense that slows the progression of symptoms in neurodegenerative diseases. Here we evaluated, for the first time, the therapeutic effect of human pericytes in vivo in SOD1 mice and in vitro in motor neurons and other neuronal cells derived from one ALS patient. Pericytes and mesenchymal stromal cells (MSCs) were derived from the same adipose tissue sample and were administered to SOD1 mice intraperitoneally. The effect of the two treatments was compared. Treatment with pericytes extended significantly animals survival in SOD1 males, but not in females that usually have a milder phenotype with higher survival rates. No significant differences were observed in the survival of mice treated with MSCs. Gene expression analysis in brain and spinal cord of end-stage animals showed that treatment with pericytes can stimulate the host antioxidant system. Additionally, pericytes induced the expression of SOD1 and CAT in motor neurons and other neuronal cells derived from one ALS patient carrying a mutation in FUS. Overall, treatment with pericytes was more effective than treatment with MSCs. Our results encourage further investigations and suggest that pericytes may be a good option for ALS treatment in the future. Graphical Abstractᅟ

Different Donors Mesenchymal Stromal Cells Secretomes Reveal Heterogeneous Profile of Relevance for Therapeutic Use

Duchenne muscular dystrophy (DMD) is a lethal X-linked disorder caused by null mutations in the dystrophin gene. Although the primary defect is the deficiency of muscle dystrophin, secondary events, including chronic inflammation, fibrosis, and muscle regeneration failure are thought to actively contribute to disease progression. Despite several advances, there is still no effective therapy for DMD. Therefore, the potential regenerative capacities, and immune-privileged properties of mesenchymal stromal cells (MSCs), have been the focus of intense investigation in different animal models aiming the treatment of these disorders. However, these studies have shown different outcomes according to the sources from which MSCs were obtained, which raise the question whether stem cells from distinct sources have comparable clinical effects. Here, we analyzed the protein content of the secretome of MSCs, isolated from three different sources (adipose tissue, skeletal muscle, and uterine tubes), obtained from five donors and evaluated their in vitro properties when cocultured with DMD myoblasts. All MSC lineages showed pathways enrichment related to protein metabolic process, oxidation-reduction process, cell proliferation, and regulation of apoptosis. We found that MSCs secretome proteins and their effect in vitro vary significantly according to the tissue and donors, including opposite effects in apoptosis assay, indicating the importance of characterizing MSC secretome profile before its use in animal and clinical trials. Despite the individual differences a pool of conditioned media from all MSCs lineages was able to delay apoptosis and enhance migration when in contact with DMD myoblasts.

Phenotypes in golden retriever.

Sir, The commentary by Shelton and Engvall (Neuromusc. Disorders 2009;19:800–1) on Ambrosio et al. [1] are very pertinent and we agree with them. This paper was written and sent to publication without the knowledge of our group at the Human Genome Research Center. Our contribution to this paper was the genotyping of the dogs. The small sample of only 15 dogs included in this manuscript is indeed not representative of the 77 affected dogs born in this kennel to date. As far as we could observe, all dogs received comparable care during the postnatal period or afterwards and therefore the variable phenotype is probably not caused by differences in animal care. However, there are several other important errors in this report, regarding literature citation and interpretation, analysis of the data and even observation of the dogs, as pointed out in our subsequent letter to the Editor of the journal [2]. For example, it is stated in the paper that ‘‘no variation in phenotype is seen among affected females”, which is not what we observed. Although the number of affected females born in the kennel is relatively small (n = 13) they have a variable course, comparable to their male litter mates. It is also important to point out that the kennel was established after the donation of Beth, a female GRMD carrier, by the group of Joe Kornegay (University of North Carolina) and contrary to what is stated in the paper, it is not the only GRMD kennel in Latin America. There is another

Comments to the paper by Ambrósio CE, Fadel L, Gaiad TP, Martins DS, et al. [Identification of three distinguishable phenotypes in golden retriever muscular dystrophy (Genet. Mol. Res. 2009 Apr 7;8 (2): 389-396)].

Duchenne muscular dystrophy (DMD) is a human disease characterized by progressive and irreversible skeletal muscle degeneration caused by mutations in the dystrophin gene, which codifies the protein dystrophin (Francke et al., 1985; Kunkel et al., 1985; Ray et al., 1985; Hoffman et al., 1987), instead of “mutations in genes coding for important muscle proteins”; - Dogs had their disease status confirmed by genotyping, which means polymerase chain reaction (PCR) analysis followed by restriction fragment length polymorphism (RFLP), as described by Sharp et al. (1992) and Honeyman et al. (1999); - DMD patients DO NOT show significant inter- and intrafamiliar clinical variability comparable to the GRMD dog model. In DMD, the progression of the disease is always severe and predictable, and differently from the GRMD dogs there is no neonatal death in humans. In opposition, in Becker muscular dystrophy (BMD), allelic to DMD, we and others observe a wide variability (intra- and inter-familial) in the severity of the phenotype (Vainzof et al., 1993).