Denise Griffiths

Osteogenic protein-1 (bone morphogenetic protein-7) reduces severity of injury after ischemic acute renal failure in rat.

We have shown that osteogenic protein-1 (OP-1) (bone morphogenetic protein-7) is responsible for the induction of nephrogenic mesenchyme during embryonic kidney development. Gene knock-out studies showed that OP-1 null mutant mice die of renal failure within the first day of postnatal life. In the present study, we evaluated the effect of recombinant human OP-1 for the treatment of acute renal failure after 60 min bilateral renal artery occlusion in rats. Bioavailability studies in normal rats indicate that approximately 1.4 microg OP-1/ml is available in the circulation 1 min after intravenous administration of 250 microg/kg, which then declines steadily with a half life of 30 min. About 0.5% of the administered OP-1 dose/g tissue is targeted for OP-1 receptors in the kidney. We show that OP-1 preserves kidney function, as determined by reduced blood urea nitrogen and serum creatinine, and increased survival rate when administered 10 min before or 1 or 16 h after ischemia, and then at 24-h intervals up to 72 h after reperfusion. Histochemical and molecular analyses demonstrate that OP-1: (a) minimizes infarction and cell necrosis, and decreases the number of plugged tubules; (b) suppresses inflammation by downregulating the expression of intercellular adhesive molecule, and prevents the accumulation and activity of neutrophils; (c) maintains the expression of the vascular smooth muscle cell phenotype in pericellular capillaries; and (d) reduces programmed cell death during the recovery. Collectively, these data suggest that OP-1 prevents the loss of kidney function associated with ischemic injury and may provide a basis for the treatment of acute renal failure.

Delivery of AAV-IGF-1 to the CNS extends survival in ALS mice through modification of aberrant glial cell activity.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease of the motor system. Recent work in rodent models of ALS has shown that insulin-like growth factor-1 (IGF-1) slows disease progression when delivered at disease onset. However, IGF-1s mechanism of action along the neuromuscular axis remains unclear. In this study, symptomatic ALS mice received IGF-1 through stereotaxic injection of an IGF-1-expressing viral vector to the deep cerebellar nuclei (DCN), a region of the cerebellum with extensive brain stem and spinal cord connections. We found that delivery of IGF-1 to the central nervous system (CNS) reduced ALS neuropathology, improved muscle strength, and significantly extended life span in ALS mice. To explore the mechanism of action of IGF-1, we used a newly developed in vitro model of ALS. We demonstrate that IGF-1 is potently neuroprotective and attenuates glial cell-mediated release of tumor necrosis factor-alpha (TNF-alpha) and nitric oxide (NO). Our results show that delivering IGF-1 to the CNS is sufficient to delay disease progression in a mouse model of familial ALS and demonstrate for the first time that IGF-1 attenuates the pathological activity of non-neuronal cells that contribute to disease progression. Our findings highlight an innovative approach for delivering IGF-1 to the CNS.

Combination brain and systemic injections of AAV provide maximal functional and survival benefits in the Niemann-Pick mouse.

Niemann-Pick disease (NPD) is caused by the loss of acid sphingomyelinase (ASM) activity, which results in widespread accumulation of undegraded lipids in cells of the viscera and CNS. In this study, we tested the effect of combination brain and systemic injections of recombinant adeno-associated viral vectors encoding human ASM (hASM) in a mouse model of NPD. Animals treated by combination therapy exhibited high levels of hASM in the viscera and brain, which resulted in near-complete correction of storage throughout the body. This global reversal of pathology translated to normal weight gain and superior recovery of motor and cognitive functions compared to animals treated by either brain or systemic injection alone. Furthermore, animals in the combination group did not generate antibodies to hASM, demonstrating the first application of systemic-mediated tolerization to improve the efficacy of brain injections. All of the animals treated by combination therapy survived in good health to an investigator-selected 54 weeks, whereas the median lifespans of the systemic-alone, brain-alone, or untreated ASM knockout groups were 47, 48, and 34 weeks, respectively. These data demonstrate that combination therapy is a promising therapeutic modality for treating NPD and suggest a potential strategy for treating disease indications that cause both visceral and CNS pathologies.

Intracerebroventricular infusion of acid sphingomyelinase corrects CNS manifestations in a mouse model of Niemann-Pick A disease.

Niemann-Pick A (NPA) disease is a lysosomal storage disorder (LSD) caused by a deficiency in acid sphingomyelinase (ASM) activity. Previously, we showed that the storage pathology in the ASM knockout (ASMKO) mouse brain could be corrected by intracerebral injections of cell, gene and protein based therapies. However, except for instances where distal areas were targeted with viral vectors, correction of lysosomal storage pathology was typically limited to a region within a few millimeters from the injection site. As NPA is a global neurometabolic disease, the development of delivery strategies that maximize the distribution of the enzyme throughout the CNS is likely necessary to arrest or delay progression of the disease. To address this challenge, we evaluated the effectiveness of intracerebroventricular (ICV) delivery of recombinant human ASM into ASMKO mice. Our findings showed that ICV delivery of the enzyme led to widespread distribution of the hydrolase throughout the CNS. Moreover, a significant reduction in lysosomal accumulation of sphingomyelin was observed throughout the brain and also within the spinal cord and viscera. Importantly, we demonstrated that repeated ICV infusions of ASM were effective at improving the disease phenotype in the ASMKO mouse as indicated by a partial alleviation of the motor abnormalities. These findings support the continued exploration of ICV delivery of recombinant lysosomal enzymes as a therapeutic modality for LSDs such as NPA that manifests substrate accumulation within the CNS.

Intraparenchymal injections of acid sphingomyelinase results in regional correction of lysosomal storage pathology in the Niemann-Pick A mouse

Niemann-Pick A disease (NPD-A) is caused by a deficiency of acid sphingomyelinase (ASM) leading to the intracellular accumulation of sphingomyelin and cholesterol in lysosomes. We evaluated the effects of direct intraparenchymal brain injections of purified recombinant human ASM (hASM) at correcting the storage pathology in a mouse model of NPD-A (ASMKO). Different doses (0.1 ng to 10 mug of hASM) were injected into the right hemisphere of the hippocampus and thalamus of 12- to 14-week-old ASMKO mice. Immunohistochemical analysis after 1 week indicated that animals treated with greater than 1 mug hASM/site showed detectable levels of enzyme around the injected regions. However, localized clearance of sphingomyelin and cholesterol storage were observed in animals administered lower doses of enzyme, starting at 100 ng hASM/site. Areas of correction were also noted at distal sites such as in the contralateral hemispheres. Indications of storage re-accumulation were seen after 2 weeks post-injection. Injections of hASM did not cause any significant cell infiltration, astrogliosis, or microglial activation. These results indicate that intraparenchymal injection of hASM is associated with minimal toxicity and can lead to regional reductions in storage pathology in the ASMKO mouse.

Optimized Preservation of CNS Morphology for the Identification of Glycogen in the Pompe Mouse Model

Pompe disease (glycogenosis type II) is a rare lysosomal disorder caused by a mutational deficiency of acid α-glucosidase (GAA). This deficiency leads to glycogen accumulation in multiple tissues: heart, skeletal muscles, and the central nervous system. A knockout mouse model mimicking the human condition has been used for histological evaluation. Currently, the best method for preserving glycogen in Pompe samples uses epon–araldite resin. Although the preservation by this method is excellent, the size of the tissue is limited to 1 mm3. To accurately evaluate brain pathology in the Pompe mouse model, a modified glycol methacrylate (JB-4 Plus) method was developed. This approach allowed the production of larger tissue sections encompassing an entire mouse hemisphere (8 × 15 mm) while also providing a high level of morphological detail and preservation of glycogen. Application of the JB-4 Plus method is appropriate when a high level of cellular detail is desired. A modified paraffin method was also developed for use when rapid processing of multiple samples is a priority. Traditional paraffin processing results in glycogen loss. The modified paraffin method with periodic acid postfixation resulted in improved tissue morphology and glycogen preservation. Both techniques provide accurate anatomic evaluation of the glycogen distribution in Pompe mouse brain. (J Histochem Cytochem 55:991–998, 2007)

Optimization of a histopathological biomarker for sphingomyelin accumulation in acid sphingomyelinase deficiency.

Niemann-Pick disease (types A and B), or acid sphingomyelinase deficiency, is an inherited deficiency of acid sphingomyelinase, resulting in intralysosomal accumulation of sphingomyelin in cells throughout the body, particularly within those of the reticuloendothelial system. These cellular changes result in hepatosplenomegaly and pulmonary infiltrates in humans. A knockout mouse model mimics many elements of human ASMD and is useful for studying disease histopathology. However, traditional formalin-fixation and paraffin embedding of ASMD tissues dissolves sphingomyelin, resulting in tissues with a foamy cell appearance, making quantitative analysis of the substrate difficult. To optimize substrate fixation and staining, a modified osmium tetroxide and potassium dichromate postfixation method was developed to preserve sphingomyelin in epon-araldite embedded tissue and pulmonary cytology specimens. After processing, semi-thin sections were incubated with tannic acid solution followed by staining with toluidine blue/borax. This modified method provides excellent preservation and staining contrast of sphingomyelin with other cell structures. The resulting high-resolution light microscopy sections permit digital quantification of sphingomyelin in light microscopic fields. A lysenin affinity stain for sphingomyelin was also developed for use on these semi-thin epon sections. Finally, ultrathin serial sections can be cut from these same tissue blocks and stained for ultrastructural examination by electron microscopy.

110. Performance of Different AAV Serotype Vectors Following Injection into the Deep Cerebellar Nuclei of ASMKO Mouse Brain

Niemann-Pick A disease (NPA) is a lysosomal storage disorder caused by a deficiency in acid sphingomyelinase (ASM) activity. Consequent accumulation of sphingomyelin and other lipids in the CNS results in the development of a rapidly progressive neurodegenerative disease with death occurring by 2 to 3 years of age. Previously we have shown that the storage pathology in the ASM knockout (ASMKO) mouse brain is amenable to AAV2/2-mediated gene therapy. Interestingly, correction of storage pathology occurred not only at the injection site, but also in regions that send and/or receive input from the injection site|[ndash]|suggesting that AAV vector and/or expressed ASM protein underwent transport. The present experiment evaluated the relative ability of recombinant AAV2/1, AAV2/2, AAV2/5, AAV2/7 and AAV2/8 serotype vectors encoding human ASM to facilitate gene transduction, express ASM protein, correct cholesterol storage pathology, undergo transport, rescue Purkinje cells, and initiate functional recovery in the ASMKO mouse. Male ASMKO mice (|[sim]|7 weeks old) were unilaterally injected with the different AAV serotype vectors within the deep cerebellar nuclei of the cerebellum (DCN). The DCN was targeted because it is highly connected with the CNS; and therefore, may provide a means to achieve widespread ASM expression throughout the brain. Mice were sacrificed at 14 weeks of age after undergoing rotarod testing. Mice injected with AAV2/1 and AAV2/8 demonstrated significant functional improvement on the rotarod, whereas mice injected with AAV2/2, AAV2/5 and AAV2/7 did not. Consistent with the behavioral results, cerebellar ASM protein levels (as detected by ELISA) were significantly higher in mice injected with AAV2/1 and AAV2/8, than mice injected with AAV2/2, AAV2/5, AAV2/7 and control mice. Preservation of Purkinje cells based on calbindin immunostaining was greatest in mice injected with AAV2/1 and AAV2/8. In all AAV-ASM treated mice, expression of ASM led to widespread clearance of filipin/cholesterol staining in the cerebellum, brainstem, and midbrain|[ndash]|indicating that AAV vector and/or expressed ASM underwent transport from the DCN. Overall, a positive relationship between ASM protein levels, filipin clearance, Purkinje cell survival, and rotarod performance was observed. These results support the further evaluation of AAV2/1 and AAV2/8-based vectors for gene therapy of the CNS manifestations in Niemann-Pick A disease.