Correction of metachromatic leukodystrophy in the mouse model by transplantation of genetically modified hematopoietic stem cells
Alessandra Biffi, Michele De Palma, Angelo Quattrini, Ubaldo Del Carro, Stefano Amadio, Ilaria Visigalli, Maria Sessa, Stefania Fasano, Riccardo Brambilla, Sergio Marchesini, Claudio Bordignon, Luigi Naldini
Alessandra Biffi, Michele De Palma, Angelo Quattrini, Ubaldo Del Carro, Stefano Amadio, Ilaria Visigalli, Maria Sessa, Stefania Fasano, Riccardo Brambilla, Sergio Marchesini, Claudio Bordignon, Luigi Naldini
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Article Genetics

Correction of metachromatic leukodystrophy in the mouse model by transplantation of genetically modified hematopoietic stem cells

Abstract

Gene-based delivery can establish a sustained supply of therapeutic proteins within the nervous system. For diseases characterized by extensive CNS and peripheral nervous system (PNS) involvement, widespread distribution of the exogenous gene may be required, a challenge to in vivo gene transfer strategies. Here, using lentiviral vectors (LVs), we efficiently transduced hematopoietic stem cells (HSCs) ex vivo and evaluated the potential of their progeny to target therapeutic genes to the CNS and PNS of transplanted mice and correct a neurodegenerative disorder, metachromatic leukodystrophy (MLD). We proved extensive repopulation of CNS microglia and PNS endoneurial macrophages by transgene-expressing cells. Intriguingly, recruitment of these HSC-derived cells was faster and more robust in MLD mice. By transplanting HSCs transduced with the arylsulfatase A gene, we fully reconstituted enzyme activity in the hematopoietic system of MLD mice and prevented the development of motor conduction impairment, learning and coordination deficits, and neuropathological abnormalities typical of the disease. Remarkably, ex vivo gene therapy had a significantly higher therapeutic impact than WT HSC transplantation, indicating a critical role for enzyme overexpression in the HSC progeny. These results indicate that transplantation of LV-transduced autologous HSCs represents a potentially efficacious therapeutic strategy for MLD and possibly other neurodegenerative disorders.

Authors

Alessandra Biffi, Michele De Palma, Angelo Quattrini, Ubaldo Del Carro, Stefano Amadio, Ilaria Visigalli, Maria Sessa, Stefania Fasano, Riccardo Brambilla, Sergio Marchesini, Claudio Bordignon, Luigi Naldini

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ARSA activity reconstitution and neurophysiological analysis of transpla...
ARSA activity reconstitution and neurophysiological analysis of transplanted MLD mice. (A) Sulfatide assay on PBMCs from mice transplanted with ARSA-transduced (ARSA-LV) or GFP-transduced (As2–/–) HSCs, 7 months after BMT, and from WT mice. Sulfatide metabolism in WT and reconstituted As2–/– mice is shown by LRh-sulfatide reduction and appearance of galactosylceramide (LRh-GalCer) (average and range of picomoles normalized for total protein content). (B) PNC assay on PBMCs as in A. ARSA activity is expressed relative to the value obtained from WT mice. Full ARSA activity reconstitution and overexpression above the WT level was observed in ARSA-transplanted mice. (C–E) Neurophysiological assessment of central and peripheral motor conduction in 8-month-old MLD mice transplanted with ARSA- or GFP-transduced HSCs, and WT mice with the same genetic background (n = 15 mice per group). Significantly lower CCTs (C) and F wave latency values (D), and significantly higher sciatic MCV values (E) were recorded in ARSA- transplanted mice compared with GFP controls. Comparison with WT shows nearly complete prevention of motor conduction impairments (P > 0.05 for all parameters). (F–H) Neurophysiological assessment in the same groups of ARSA- and mock-transplanted mice as in C–E, at 12 months of age, and in age-matched, WT HSC–transplanted mice (n = 10 mice per group). The analysis shows maintenance of the therapeutic effect in ARSA-transplanted mice and significantly faster motor conduction as compared with WT HSC–transplanted ones (*P < 0.01 between ARSA-LV and As2–/–; ***P < 0.05 between ARSA-LV and WT HSC–transplanted mice). Data are expressed as single recordings and means.