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During brain maturation, cation-independent mannose-6-phosphate receptor (CI-MPR), a key transporter for lysosomal hydrolases, decreases significantly on the blood-brain barrier (BBB). Such a phenomenon leads to poor brain penetration of therapeutic enzymes and subsequent failure in reversing neurological complications in patients with neuropathic lysosomal storage diseases (nLSDs), such as Hurler syndrome (severe form of mucopolysaccharidosis type I [MPS I]). In this study, we discover that upregulation of microRNA-143 (miR-143) contributes to the decline of CI-MPR on the BBB during development. Gain- and loss-of-function studies showed that miR-143 inhibits CI-MPR expression and its transport function in human endothelial cells in vitro. Genetic removal of miR-143 in MPS I mice enhances CI-MPR expression and improves enzyme transport across the BBB, leading to brain metabolic correction, pathology normalization, and correction of neurological functional deficits 5 months after peripheral protein delivery at clinically relevant levels that derived from erythroid/megakaryocytic cells via hematopoietic stem cell-mediated gene therapy, when otherwise no improvement was observed in MPS I mice at a parallel setting. These studies not only uncover a novel role of miR-143 as an important modulator for the developmental decline of CI-MPR on the BBB, but they also demonstrate the functional significance of depleting miR-143 for “rescuing” BBB-anchored CI-MPR on advancing CNS treatment for nLSDs.

Intraosseous (IO) infusion of lentiviral vectors (LVs) for in situ gene transfer into bone marrow may avoid specific challenges posed by ex vivo gene delivery, including, in particular, the requirement of preconditioning. We utilized IO delivery of LVs encoding a GFP or factor VIII (FVIII) transgene directed by ubiquitous promoters (a MND or EF-1α-short element; M-GFP-LV, E-F8-LV) or a platelet-specific, glycoprotein-1bα promoter (G-GFP-LV, G-F8-LV). A single IO infusion of M-GFP-LV or G-GFP-LV achieved long-term and efficient GFP expression in Lineage-Sca1+c-Kit+ hematopoietic stem cells and platelets, respectively. While E-F8-LV produced initially high-level FVIII expression, robust anti-FVIII immune responses eliminated functional FVIII in circulation. In contrast, IO delivery of G-F8-LV achieved long-term platelet-specific expression of FVIII, resulting in partial correction of hemophilia A. Furthermore, similar clinical benefit with G-F8-LV was achieved in animals with pre-existing anti-FVIII inhibitors. These findings further support platelets as an ideal FVIII delivery vehicle, as FVIII, stored in α-granules, is protected from neutralizing antibodies and, during bleeding, activated platelets locally excrete FVIII to promote clot formation. Overall, a single IO infusion of G-F8-LV was sufficient to correct hemophilia phenotype for long term, indicating that this approach may provide an effective means to permanently treat FVIII deficiency.

Mucopolysaccharidosis type I (MPS I) is a progressive lysosomal storage disorder with systemic and central nervous system (CNS) involvement due to deficiency of α-l-iduronidase (IDUA). We previously identified a receptor-binding peptide from apolipoprotein E (e) that facilitated a widespread delivery of IDUAe fusion protein into CNS. In this study, we evaluated the long-term CNS biodistribution, dose-correlation, and therapeutic benefits of IDUAe after systemic, sustained delivery via hematopoietic stem cell (HSC)-mediated gene therapy with expression restricted to erythroid/megakaryocyte lineages. Compared to the highest dosage group treated by nontargeted control IDUAc (165 U/ml), physiological levels of IDUAe in the circulation (12 U/ml) led to better CNS benefits in MPS I mice as demonstrated in glycosaminoglycan accumulation, histopathology analysis, and neurological behavior. Long-term brain metabolic correction and normalization of exploratory behavior deficits in MPS I mice were observed by peripheral enzyme therapy with physiological levels of IDUAe derived from clinically attainable levels of HSC transduction efficiency (0.1). Importantly, these levels of IDUAe proved to be more beneficial on correction of cerebrum pathology and behavioral deficits in MPS I mice than wild-type HSCs fully engrafted in MPS I chimeras. These results provide compelling evidence for CNS efficacy of IDUAe and its prospective translation to clinical application.

Murine models of lysosomal storage diseases provide an opportunity to evaluate the potential for gene therapy to prevent systemic manifestations of the disease. To determine the potential for treatment of mucopolysaccharidosis type I using a gene delivery approach, a recombinant adeno-associated virus (AAV) vector, vTRCA1, transducing the human iduronidase (IDUA) gene was constructed and 1 x 10(10) particles were injected intravenously into 1-day-old Idua(-/-) mice. High levels of IDUA activity were present in the plasma of vTRCA1-treated animals that persisted for the 5-month duration of the study, with heart and lung of this group demonstrating the highest tissue levels of gene transfer and enzyme activity overall. vTRCA1-treated Idua(-/-) animals with measurable plasma IDUA activity exhibited histopathological evidence of reduced lysosomal storage in a number of tissues and were normalized with respect to urinary GAG excretion, craniofacial bony parameters, and body weight. In an open field test, vTRCA1-treated Idua(-/-) animals exhibited a significant reduction in total squares covered and a trend toward normalization in rearing events and grooming time compared to control-treated Idua(-/-) animals. We conclude that AAV-mediated transduction of the IDUA gene in newborn Idua(-/-) mice was sufficient to have a major curative impact on several of the most important parameters of the disease.

Lentiviral vectors can confer high levels of gene transfer and transgene expression in a variety of cell types. However, the biodistribution and toxicity after intravenous administration have not been reported. To address these issues of biodistribution and toxicity, an HIV-1-based vector, HR'cmvGFP, was administered to normal BALB/c mice by tail-vein injection. Nine different organs and bone marrow were evaluated by real-time quantitative PCR (QPCR) assay capable of a broad range of quantitation (5-log fold) to detect as few as one copy of the green fluorescent protein gene (GFP) per 10(5) cells. Four days after vector administration, high levels of transgene and gene expression were observed in liver, spleen, and bone marrow in all animals. By 40 days after injection, GFP levels had decreased in liver and spleen, but bone marrow exhibited a consistently high level of transgene. This finding was consistent with the increase in both GFP frequency and expression levels observed in peripheral blood by fluorescence-activated cell-sorting (FACS) analysis. Between 0 and 1% transgene was detected in all other organs. No significant pathologic lesions were found attributable to vector in any of the tissues examined. The observation of bone marrow transduction after intravenous vector administration suggests the possibility of an in vivo approach to stem cell gene therapy.

There has no effective treatment for neuronopathic Gaucher Disease (nGD) due to the difficulty of therapeutics to cross the blood-brain-barrier. Platelets are blood elements that contain cytoplasmic secretory vesicles containing proteins involved in hemostasis, inflammation and angiogenesis. We have recently shown that platelets/megakaryocytes could serve as efficient and protective depots for lysosomal enzyme generation and distribution. In this study the potential therapeutic benefits of platelet transfusion in treating neuronopathic GD (nGD) was evaluated using a murine model of acute nGD (4L;C), which resembles types 2 and 3 Gaucher disease. Platelets containing significant amounts of wild type acid s-glucosidase enzyme (GCase) were isolated from GFP mice and transfused weekly into 4L;C mice for four times beginning at 21 days of age, resulting in an average 10-13% of donor-derived GFP+ platelets in circulation with half-life of 52 hr. Importantly, moderate platelet transfusion led to significantly increase of life-span in 4L;C mice from 47 days to 55 days with reduction of splenomegaly. The accumulation of glycosylsphingosin was significantly reduced in spleen, liver and brain. Moreover, the abnormal walk patterns with splaying of hindlimbs exhibited in 4L;C mice were improved significantly in platelet-treated mice, indicating amelioration of motor neuron dysfunction and hindlimb paresis. The improvement of short-term memory deficit in treated 4L;C mice was evidenced in repeated open-field test. Immunohistochemistry analysis showed that the elevated brain CD68+ signals, a marker for activated microglia cells, were normalized in cerebellum folium and middle brain regions, and partially corrected in the cortex, cerebellum DCN, brainstem, thalamus and spinal cord of treated 4L;C mice, indicating the reduction of pro-inflammation by platelet transfusion. Notably, RIPK3-positive signals within Purkinje neurons in cerebellum of nGD mice were significantly reduced, suggesting therapeutic benefit of platelet transfusion on neuronal necroptosis. This study reveals an under-appreciated, unexpected role for platelets in treating CNS diseases. These results provide proof of concept that platelet transfusion can achieve CNS benefits with brain substrate reduction and improvement in neurological function, as well as reducing pro-inflammation and neuronal necroptosis. The findings will open a door for new clinical approaches with platelet transfusion in treating nGD and potentially other brain diseases.

strategy is hampered by low efficiency of gene transfer and expression in repopulating HSC. To overcome this problem, we analyze the effect of overexpression of HoxB4, which can expand HSC, in mouse BM cells by transplantation of MLD mice. 5FU treated GFP mouse BM cells were transduced with retroviral vector expressing HoxB4 (B4) or control retroviral vector expressing GFP (MIG). After expansion of these transduced cells in vitro for five days transplantation was performed into irradiated MLD mice. High level of engraftment was observed in B4 transplanted MLD mice (B4MLD) compared to MIG transplanted MLD mice (MIGMLD)(92.4 vs. 36.5 %). ASA enzyme activity in serum was also increased in B4MLD compared to MIGMLD (19.8 vs. 10.3 nm/mg/hr). To evaluate the contribution of bone marrow cells as carriers for gene therapy of neurological disorders, we studied the fate of transplanted BM cells in the adult mouse brain. Efficient GFP positive neuronal cells were detected in B4MLD brain compared to MIGMLD brain. Immunohistochemical staining showed that most of the GFP positive cells ware IbaI positive microglia cells as we and others reported. In addition, O4 positive oligodendocyte like cells were identified only in the B4MLD brain but not in the MIGMLD brain (O4 positive/GFP positive: 6/326 vs. 0/312). This is the first demonstration indicating that systemically infused HSCc could differentiate to oligodendrocytes in adult mouse brain. It was recently suggested that HoxB4 could play a role in oligodendrocyte maturation. Our data strongly support that HSCs transduced with HoxB4 expression vector are useful for ex vivo gene therapy of CNS disorders as carriers of production of therapeutic protein and for regeneration of oligodendrocytes to treat demyelinating disorders such as MLD, Krabbe disease, and multiple sclerosis.

The potential of in vivo bone marrow stem cell gene transfer by bone cavity injection has not been explored. This approach could take full advantage of any source of stem cells present in bone cavity and avoid many of the difficulties encountered by ex vivo hematopoietic stem cell (HSC) gene transfer. To determine if efficient gene transfer can be achieved in HSC and mesenchymal stem cells (MSC) by in situ delivery of a HIV-based lent virus vector (LV), we intrafemorally injected into adult normal mice (Ly5.1) with a self-inactivating GFP-containing LV (at 2|[times]|106 IU/mouse). GFP-expressing peripheral blood leukocytes (PBL) were observed in both myeloid (up to 4%) and lymphoid subpopulations (up to 2%) 3-month post injection. The colony-forming cell (CFC) assay resulted in 4|[ndash]|5% of GFP-expressing CFUs with multilineage potentials 4-months after injection, which was consistent with 4-color FACS analysis data demonstrating up to 3.7% of GFP+ HSC/progenitors (Lin-c-kit+Sca1+). Higher frequencies of GFP-containing CFUs (up to 15.9%) were revealed by a colony-direct duplex PCR. To further evaluate HSC gene transfer, bone marrow from injected mice was transplanted into lethally irradiated adult C57BL/6 (Ly5.2) mice with successful engraftment demonstrated by 97.5-98.5% donor-derived PBL in all recipients 3-months post BMT. Four months after transplantation, we observed 8.4 to 17.7 % GFP-expressing CFUs, as well as 16 to 24% GFP-containing CFUs in all recipients. Vector integrants and their multi-clonality were further confirmed by linear-amplification mediated PCR (LAM-PCR) in both primary injected and secondary transplanted mice. We also demonstrated that GFP-expressing MSC retained multiple differentiation potential. Our data provide the first evidence that adult stem cells in bone marrow could be efficiently transduced in vivo by |[ldquo]|in situ|[rdquo]| vector administration. This may potentially open a door to a novel approach for treatment of human diseases.