Identification of GLA gene deletions in Fabry patients by Multiplex Ligation-dependent Probe Amplification (MLPA)

Fabry disease is an under-recognized X-linked lysosomal disorder, due to α-galactosidase A deficiency. Most of the mutations in the GLA gene are detectable using genomic sequencing analysis. However, deletions of one or more exons or deletion encompassing the entire gene are undetectable, especially in heterozygous females. The Multiplex Ligation-dependent Probe Amplification (MLPA) is an efficient tool for discovering these rearrangements. In this study two novel different deletions were detected using MLPA assay on two Fabry patients, both resulted mutation negative by sequencing analysis. These data suggest that this screening should be systematically included in genetic testing surveys of patients with Fabry disease.     

Lentiviral-mediated gene therapy for murine mucopolysaccharidosis type IIIA

Mucopolysaccharidosis type IIIA (MPS IIIA) is a heritable glycosaminoglycan (GAG) storage disorder which is characterised by lysosomal accumulation of heparan sulphate, secondary to a deficiency of sulphamidase (heparan-N-sulphatase, N-sulphoglucosamine sulphohydrolase, EC No. 3.10.1.1.). There is currently no treatment for affected individuals who experience progressive CNS deterioration prior to an early death.As a first step towards developing gene therapy as a treatment for MPS IIIA, an MPS IIIA mouse model was used to examine the efficacy of intravenous lentiviral-mediated gene therapy. Five-week-old mice were injected with virus expressing murine sulphamidase and analysed 6 months after treatment. Transduction by the lentiviral vector was highest in the liver and spleen of treated animals, and sulphamidase activity in these tissues averaged 68% and 186% of normal, respectively.Storage was assessed using histochemical, chemical and mass spectrometric analyses. Storage in most somatic tissues was largely normalised, although chondrocytes were an obvious exception. Histologically, improvement of lysosomal storage within the brain was variable. However, β-hexosaminidase activity, which is abnormally elevated in MPS IIIA, was significantly reduced in every treated tissue, including the brain. Total uronic acid was also significantly reduced in the brains of treated mice. The level of a disaccharide marker (hexosamine-N-sulphate[α-1,4]hexuronic acid; HNS-UA) of heparan sulphate storage was also decreased in the brains of treated mice, albeit non-significantly.These results suggest that lentiviral-mediated somatic gene transfer may affect not only the somatic, but possibly also the CNS pathology, found in MPS IIIA.     

Specific T cell deletion by transfected human monocytes expressing fas ligand and antigen

The aim of our experiments was to determine whether deletion of antigen specific T helper cells could be accomplished by delivering the antigenic peptide to antigen presenting cells. Tetanus toxin peptide residues 830-843 was chosen for these experiments. Two mammalian expression vectors carrying the genes for human Fas ligand and a chimeric invariant chain-tetanus toxin peptide construct were designed. The T cell proliferative response to tetanus toxoid was inhibited when the antigen was presented by autologus monocytes transfected with Fas ligand. T cell mixture experiments using two syngeneic T cell lines specific either for tetanus toxoid or for pertussis toxin demonstrated that the killing effect elicited by the antigen pulsed/Fas ligand-transfected antigen presenting cells was antigen specific. Finally, we demonstrated that transient expression of antigen delivered by plasmid DNA can substitute for soluble antigen in the induction of antigen-specific T cell responses. Antigen presenting cells transfected with the vector carrying Fas ligand and the vector carrying the chimeric invariant chain-peptide antigen gene were shown to inhibit antigen specific T cell reactivity. This strategy may be useful for the induction of apoptosis in allopeptide reactive T cells driving chronic rejection.     

Recruitment of host's progenitor cells to sites of human amniotic fluid stem cells implantation

The amniotic fluid is a new source of multipotent stem cells with a therapeutic potential for human diseases. Cultured at low cell density, human amniotic fluid stem cells (hAFSCs) were still able to generate colony-forming unit-fibroblast (CFU-F) after 60 doublings, thus confirming their staminal nature. Moreover, after extensive in vitro cell expansion hAFSCs maintained a stable karyotype. The expression of genes, such as SSEA-4, SOX2 and OCT3/4 was confirmed at early and later culture stage. Also, hAFSCs showed bright expression of mesenchymal lineage markers and immunoregulatory properties. hAFSCs, seeded onto hydroxyapatite scaffolds and subcutaneously implanted in nude mice, played a pivotal role in mounting a response resulting in the recruitment of host's progenitor cells forming tissues of mesodermal origin such as fat, muscle, fibrous tissue and immature bone. Implanted hAFSCs migrated from the scaffold to the skin overlying implant site but not to other organs. Given their in vivo: (i) recruitment of host progenitor cells, (ii) homing towards injured sites and (iii) multipotentiality in tissue repair, hAFSCs are a very appealing reserve of stem cells potentially useful for clinical application in regenerative medicine.