Adenovirus-mediated prenatal gene transfer to murine central nervous system.

In some lysosomal storage disorders pathological alterations in the central nervous system (CNS) occur as early as the prenatal period and the neuropathology progresses rapidly soon after birth. In these diseases, postnatal therapies alone are often insufficient. Therefore prenatal gene therapy to the CNS may be necessary. In order to investigate the feasibility of gene transfer to the CNS prenatally, we administered recombinant adenovirus carrying LacZ gene to rat embryos from embryonic day 9 to 12 (E9-E12). Results showed that efficient transduction of the reporter gene to the CNS was achieved when adenoviruses were injected at E12. The regions where the reporter gene was transduced mainly localized at the telencephalon and hypophysis of the embryo, and the gene expression persisted at least 1 week after birth. In addition, when adenoviruses were injected at E9, E10 and E11, no transgene expression was detected in the CNS, but was mainly observed in the liver, the heart and the skin, respectively.

In utero fetal liver cell transplantation without toxic irradiation alleviates lysosomal storage in mice with mucopolysaccharidosis type VII.

Lysosomal storage diseases, such as Mucopolysaccharidosis type VII (MPS VII), cause progressive loss of mobility and intellect and result in early death. Treatment of progressive diseases must occur before the blood-brain barrier closes. In MPS VII mice, normal donor hematopoietic cells secrete the missing enzyme beta-glucuronidase (GUSB) that reverses disease manifestations. Correction of lysosomal storage is limited to the visceral organs unless transplantation is preceded by high-dose irradiation. We hypothesize that irradiation opens the blood-brain barrier allowing passage of corrective cells. Here we transplanted genetically myeloablated MPS VII fetuses to determine whether earlier treatment without toxic irradiation is systemically corrective. Cells with a selective advantage in utero were identified. Donor fetal liver cells (FLC), a substitute for difficult to obtain murine cord blood cells, were increased 10-fold in the host peripheral blood over equivalent numbers of adult marrow cells injected simultaneously and were stable long term in both primary and secondary hosts. GUSB- MPS VII fetuses injected with GUSB+ FLC were assessed longitudinally after birth. Donor FLC replaced host stem cell descendants, prolonged life dramatically, and reduced bone dysplasia and lysosomal storage in all tissues long term. GUSB, donor leptomeningeal cells, and microglia were present in the brain at 11 months postinjection. Lysosomal storage in cortical neurons and glia, although not completely corrected, was reduced. We conclude that in utero intervention without toxic pretreatment in this model reduces the storage disease long term and improves the length and quality of life despite exerting only minor effects on the brain.