In principle, transplantation of mesenchymal progenitor cells would attenuate or possibly correct genetic disorders of bone, cartilage and muscle, but clinical support for this concept is lacking. Here we describe the initial results of allogeneic bone marrow transplantation in three children with osteogenesis imperfecta, a genetic disorder in which osteoblasts produce defective type I collagen, leading to osteopenia, multiple fractures, severe bony deformities and considerably shortened stature. Three months after osteoblast engraftment (1.5-2.0% donor cells), representative specimens of trabecular bone showed histologic changes indicative of new dense bone formation. All patients had increases in total body bone mineral content ranging from 21 to 29 grams (median, 28), compared with predicted values of 0 to 4 grams (median, 0) for healthy children with similar changes in weight. These improvements were associated with increases in growth velocity and reduced frequencies of bone fracture. Thus, allogeneic bone marrow transplantation can lead to engraftment of functional mesenchymal progenitor cells, indicating the feasibility of this strategy in the treatment of osteogenesis imperfecta and perhaps other mesenchymal stem cell disorders as well.

Abstract-Background:The Quality Standards Subcommittee of the American Academy of Neurology and the Practice Committee of the Child Neurology Society develop practice parameters as strategies for patient management based on analysis of evidence. Objective: To review available evidence on corticosteroid treatment of boys with Duchenne dystrophy. Methods: Relevant literature was reviewed, abstracted, and classified. Recommendations were based on a four-tiered scheme of evidence classification, and areas for future research are defined. Results: Seven class I studies and numerous less rigorous trials all demonstrated that corticosteroid treatment for 6 months with prednisone (0.75 or 1.5 mg/kg/day) increased muscle strength, performance, and pulmonary function and significantly slowed the progression of weakness. Two class I trials examined the effect of lower dosage of prednisone (0.30 and 0.35 mg/kg/day), demonstrated lesser but similar benefits, and showed a lower frequency of side effects (e.g., weight gain). The only significant side effects in all class I trials were weight gain and development of a cushingoid facial appearance. One longer-term trial of daily prednisone (0.3 to 0.7 mg/kg/day), a class III study, showed prolongation of functional ability and slower progression of weakness in patients during 3 years of treatment. One class IV, open trial of alternate-day prednisone (2 mg/kg for 2 months, then two-thirds dose every other day) extended ambulation by approximately 2 years in treated compared with untreated patients. Deflazacort, a corticosteroid similar in structure to prednisone, produced similar improvement in muscle strength and function with a similar side effect profile. Conclusions: Prednisone has been demonstrated to have a beneficial effect on muscle strength and function in boys with Duchenne dystrophy and should be offered (at a dose of 0.75 mg/kg/day) as treatment. If side effects require a decrease in prednisone, tapering to dosages as low as 0.3 mg/kg/day gives less robust but significant improvement. Deflazacort (0.9 mg/kg/day) can also be used for the treatment of Duchenne dystrophy in countries in which it is available. Benefits and side effects of corticosteroid therapy need to be monitored. The offer of treatment with corticosteroids should include a balanced discussion of potential risks. NEUROLOGY 2005;64:13-20 Duchenne dystrophy (DD), an X-linked, recessive disorder, with onset before age 5 years, is the most common and severe form of childhood muscular dystrophy.1-3 The specific molecular defect is an absence or marked deficiency of dystrophin, a large membrane-associated protein that is part of the dystrophin-glycoprotein complex.1 Affected boys develop neck flexor, anterior abdominal, hip, and shoulder girdle muscle weakness in early childhood, with loss of ambulation between ages 7 and 12. 4,5 Additional material related to this article can be found on the Neurology Web site. Go to www.neurology.org and scroll down the Death usually occurs in the 20s, with the chance of...

Adult stem cells offer the potential to treat many diseases through a combination of ex vivo genetic manipulation and autologous transplantation. Mesenchymal stem cells (MSCs, also referred to as marrow stromal cells) are adult stem cells that can be isolated as proliferating, adherent cells from bones. MSCs can differentiate into multiple cell types present in several tissues, including bone, fat, cartilage, and muscle, making them ideal candidates for a variety of cell-based therapies. Here, we have used adeno-associated virus vectors to disrupt dominant-negative mutant COL1A1 collagen genes in MSCs from individuals with the brittle bone disorder osteogenesis imperfecta, demonstrating successful gene targeting in adult human stem cells.

Although biallelic mutations in non-collagen genes account for <10% of individuals with osteogenesis imperfecta, the characterization of these genes has identified new pathways and potential interventions that could benefit even those with mutations in type I collagen genes. We identified mutations in FKBP10, which encodes the 65 kDa prolyl cis-trans isomerase, FKBP65, in 38 members of 21 families with OI. These include 10 families from the Samoan Islands who share a founder mutation. Of the mutations, three are missense; the remainder either introduce premature termination codons or create frameshifts both of which result in mRNA instability. In four families missense mutations result in loss of most of the protein. The clinical effects of these mutations are short stature, a high incidence of joint contractures at birth and progressive scoliosis and fractures, but there is remarkable variability in phenotype even within families. The loss of the activity of FKBP65 has several effects: type I procollagen secretion is slightly delayed, the stabilization of the intact trimer is incomplete and there is diminished hydroxylation of the telopeptide lysyl residues involved in intermolecular cross-link formation in bone. The phenotype overlaps with that seen with mutations in PLOD2 (Bruck syndrome II), which encodes LH2, the enzyme that hydroxylates the telopeptide lysyl residues. These findings define a set of genes, FKBP10, PLOD2 and SERPINH1, that act during procollagen maturation to contribute to molecular stability and post-translational modification of type I procollagen, without which bone mass and quality are abnormal and fractures and contractures result.

Manifesting carriers of DMD gene mutations may present diagnostic challenges, particularly in the absence of a family history of dystrophinopathy. We review the clinical and genetic features in fifteen manifesting carriers identified among 860 subjects within the United Dystrophinopathy Project, a large clinical dystrophinopathy cohort whose members undergo comprehensive DMD mutation analysis. We defined manifesting carriers as females with significant weakness, excluding those with only myalgias/cramps. DNA extracted from peripheral blood was used to study X chromosome inactivation patterns. Among these manifesting carriers, age at symptom onset ranged from 2 to 47 years. Seven had no family history and eight had male relatives with Duchene muscular dystrophy (DMD). Clinical severity among the manifesting carriers varied from a DMD-like progression to a very mild Becker muscular dystrophy-like phenotype. Eight had exonic deletions or duplications and six had point mutations. One patient had two mutations (an exonic deletion and a splice site mutation), consistent with a heterozygous compound state. The X chromosome inactivation pattern was skewed toward nonrandom in four out of seven informative deletions or duplications but was random in all cases with nonsense mutations. We present the results of DMD mutation analysis in this manifesting carrier cohort, including the first example of a presumably compound heterozygous DMD mutation. Our results demonstrate that improved molecular diagnostic methods facilitate the identification of DMD mutations in manifesting carriers, and confirm the heterogeneity of mutational mechanisms as well as the wide spectrum of phenotypes.