Electrocardiographic and other cardiac anomalies in beta-glucuronidase-null mice corrected by nonablative neonatal marrow transplantation.

Cardiovascular manifestations of lysosomal storage disease (LSD) are a significant health problem for affected patients. Infantile-onset cardiac disease, because of its rapid progression, is usually treated symptomatically. Therapy in older patients includes valve replacement and bone marrow (BM) transplantation, both of which are life threatening in the already debilitated patients. Enzyme replacement therapy has potential benefit but has not yet been demonstrated to provide long-term relief for cardiac disease. Here, we demonstrate prevention of severe cardiac manifestations in beta-glucuronidase (GUSB) null mice BM-transplanted i.v. as neonates without myeloablative pretreatment. The mice, a model of mucopolysaccharidosis type VII (MPSVII, Sly syndrome), develop progressive LSD unless provided with GUSB early in life. The BM recipients retained GUSB+ donor cells in the peripheral blood and heart until necropsy at > or = 11 months of age. The enzyme beta-hexosamindase increased in tissues of GUSB null MPSVII mice was reduced significantly (P = 0.001) in treated MPSVII hearts. Electrocardiography demonstrated normalization of heart rate, PR, PQ, and QRS intervals in BM recipients. Storage was markedly reduced in the stroma of heart valves, adventitial cells of the aortic root, perivascular and interstitial cells of the myocardium, and interstitial cells of the conduction tissue. Heart/body weight ratio normalized. The aortic root was still grossly distended, and the conductive myocytes retained storage, suggesting neither plays a major role in ECG normalization. We conclude that transplantation of MPSVII neonates without toxic intervention can prevent many of the cardiovascular manifestations of LSD.

Donor cell replacement in mice transplanted in utero is limited by immune-independent mechanisms.

In utero transplantation (IUTx) therapy with allogeneic cells results in negligible peripheral blood (PBL) chimerism in nonablated humans with progressive diseases. IUTx has been successful only in immunocompromised fetuses. Because early treatment has great potential for halting disease progression, mechanisms preventing cell expansion must be identified and corrected. The hypothesis that factors in addition to allogenicity are responsible for low-level expansion is tested here by transplanting congenic cells into nonablated normal and mucopolycaccharidosis type VII (MPSVII) murine fetuses. MPSVII mice lack the enzyme beta-glucuronidase (GUSB-), accumulate glycosaminoglycans, and progressively develop severe storage disease. Low levels of enzyme can reverse storage. Evidence presented elsewhere showed that allogeneic donor cells overexpressing GUSB are negligible and their corrective effects are lost post-IUTx in MPSVII mice. We find that (1) congenic donor PBL cells, like allogeneic cells, are negligible in PBL of normal GUSB+ and MPSVII GUSB- hosts post-IUTx; (2) congenic, unlike allogeneic cells, are retained long term in both GUSB+ and GUSB- recipients; and (3) sufficient GUSB is produced to alleviate storage for up to 11.5 months in multiple tissues of GUSB- hosts. GUSB+ and GUSB- animals repopulate to a similar extent, indicating that donor GUSB enzyme does not initiate an immune response in the MPSVII null recipients. We conclude that the initial expansion of congenic and allogeneic cells is limited post-IUTx by non-immune-related mechanisms and the level of PBL cells is not necessarily indicative of graft failure following congenic IUTx. The mechanism limiting initial expansion may differ from that supporting long-term cell retention.

Prevention of systemic clinical disease in MPS VII mice following AAV-mediated neonatal gene transfer.

For many inborn errors of metabolism, early treatment is critical to prevent long-term developmental sequelae. We have previously shown that systemic treatment of neonatal mucopolysaccharidosis type VII (MPS VII) mice with recombinant adeno-associated virus (AAV) vectors results in relatively long-term expression of beta-glucuronidase (GUSB) in multiple tissues, and a reduction in lysosomal storage. Here, we demonstrate that therapeutic levels of enzyme persist for at least 1 year following a single intravenous injection of virus in neonatal MPS VII mice. The level and distribution of GUSB expression achieved is sufficient to prevent the development of many aspects of clinical disease over the life of the animal. Following treatment, bone lengths, weights and retinal function were maintained at nearly normal levels throughout the life of the animal. In addition, significant improvements in survival and auditory function were seen in AAV-treated MPS VII mice when compared with untreated mutant siblings. These data suggest that AAV-mediated gene transfer in the neonatal period can lead to prevention of many of the clinical symptoms associated with MPS VII in the murine model of this disease.

Biodistribution, kinetics, and efficacy of highly phosphorylated and non-phosphorylated beta-glucuronidase in the murine model of mucopolysaccharidosis VII.

Enzyme replacement therapy (ERT) has been shown to be effective at reducing the accumulation of undegraded substrates in lysosomal storage diseases. Most ERT studies have been performed with recombinant proteins that are mixtures of phosphorylated and non-phosphorylated enzyme. Because different cell types use different receptors to take up phosphorylated or non-phosphorylated enzyme, it is difficult to determine which form of enzyme contributed to the clinical response. Here we compare the uptake, distribution, and efficacy of highly phosphorylated and non-phosphorylated beta-glucuronidase (GUSB) in the MPS VII mouse. Highly phosphorylated murine GUSB was efficiently taken up by a wide range of tissues. In contrast, non-phosphorylated murine GUSB was taken up primarily by tissues of the reticuloendothelial (RE) system. Although the tissue distribution was different, the half-lives of both enzymes in any particular tissue were similar. Both preparations of enzyme were capable of preventing the accumulation of lysosomal storage in cell types they targeted. An important difference in clinical efficacy emerged in that phosphorylated GUSB was more efficient than non-phosphorylated enzyme at preventing the hearing loss associated with this disease. These data suggest that both forms of enzyme contribute to the clinical responses of ERT in MPS VII mice but that enzyme preparations containing phosphorylated GUSB are more broadly effective than non-phosphorylated enzyme.

Intracranial injection of recombinant adeno-associated virus improves cognitive function in a murine model of mucopolysaccharidosis type VII.

Mucopolysaccharidosis type VII (MPS VII) is a lysosomal storage disease caused by the lack of beta-glucuronidase (GUSB) activity. GUSB deficiency leads to the progressive accumulation of undegraded glycosaminoglycans (GAGs) in cells of most tissues, including the brain, and is associated with mental retardation. Reduction of lysosomal storage in the central nervous system and prevention of cognitive dysfunction may require intracranial delivery of a therapeutic agent during the newborn period that provides a continuous source of GUSB. Therefore, we injected recombinant adeno-associated virus encoding human GUSB into both the anterior cortex and the hippocampus of newborn MPS VII mice. Total GUSB activity in the brain approached normal levels by 18 weeks. Although GUSB activity was concentrated near the injection sites, lysosomal distension was reduced in most areas of the brain. In addition to histopathologic evidence of GAG reduction, the previously undescribed accumulation of GM2 and GM3 gangliosides in the brain was also prevented. Furthermore, GUSB expression and reduced lysosomal distension correlated with improvements in cognitive function as measured in the Morris Water Maze test. These findings indicate that localized overexpression of GUSB has positive effects on the pathology and cognitive function and does not have overt toxicity.

Nonablative neonatal marrow transplantation attenuates functional and physical defects of beta-glucuronidase deficiency.

The toxicity of preparative regimens render neonatal bone marrow transplantation (BMT) for progressive childhood diseases a controversial treatment. Ablative BMT in neonatal mice with or without the lysosomal storage disease mucopolysaccharidosis type VII (MPS VII) show high morbidity and developmental disruption of both brain and bone structure. In this investigation, BMT was performed with a high dose of congenic, normal bone marrow into nonablated newborn mice. Recipients had lifelong, multilineage, peripheral blood chimerism with the donor beta-glucuronidase-positive (GUS(+)) cells that was both well tolerated and therapeutic. Three daily injections of normal adult marrow increased the average life span by at least 6 months and corrected the functional breeding deficits typical of the MPS VII mice. Twelve months after injection, several structural features of femurs were more like that of normal mice than of untreated MPS VII mice. Periosteal circumference and bone cortical thickness were significantly improved in males and cortical density did not differ significantly from values in normal females. Significant reduction of lysosomal glycosaminoglycan storage corresponded directly with GUS enzyme activity and percentage of histochemically GUS(+) cells in visceral organs and hematopoietic tissues such as thymus, spleen, peripheral blood, and bone marrow. By all criteria tested, BMT into neonatal MPS VII mice in the absence of any preparative regimen is a successful therapy.

Morphology of liver repair following cholestatic liver injury: resolution of ductal hyperplasia, matrix deposition and regression of myofibroblasts.

BACKGROUND/AIMS: Myofibroblasts are the primary cells responsible for increased matrix deposition in hepatic fibrosis. Activation of hepatic stellate cells and portal fibroblasts to myofibroblasts during cholestatic liver injury is accompanied by increased expression of the activation marker, alpha-smooth muscle actin (SMA), and collagen genes. In contrast to our understanding of injury, the cellular mechanisms of liver repair are not well defined. This study was designed to examine the morphological relationship between bile duct hyperplasia, matrix deposition and myofibroblast phenotype in a model of chronic cholestatic liver injury and repair. METHODS: Reversible extrahepatic obstruction was accomplished in rats using a soft vessel loop suspended from the anterior abdominal wall: duct manipulation alone was performed in sham-operated controls. After 7 days, rats were either sacrificed or decompressed by release of the loop and subsequently sacrificed 2-10 days after reversal. Liver sections were obtained for in situ hybridization for procollagen alpha1(I) mRNA, immunohistochemical staining for SMA and cytokeratin 19, and histochemical staining for reticulin. RESULTS: Cholestatic livers demonstrated bile duct hyperplasia, which reversed to normal within 10 days after decompression. Fibrosis was also substantially reduced during this period. SMA-positive myofibroblasts were abundant and localized to regions adjacent to proliferating ducts and excess matrix in the obstructed animals. Decompressed livers showed a dramatic time-dependent reduction in the number of SMA-positive cells and in the expression of procollagen I mRNA. CONCLUSIONS: Our results show that the disappearance of bile duct hyperplasia after biliary decompression is accompanied by a similarly rapid loss of SMA-positive myofibroblasts. Both cellular events may abrogate enhanced matrix synthesis and allow repair to occur.

Retinal function is improved in a murine model of a lysosomal storage disease following bone marrow transplantation.

Mucopolysaccharidoses are heritable lysosomal storage diseases caused by deficiencies in acid hydrolases involved in the sequential degradation of complex glycosaminoglycans (GAGs). In many mucopolysaccharidoses, GAGs accumulate in the retinal pigment epithelial (RPE) cells of the eye resulting in pronounced lysosomal distension. It is not clear how the progressive accumulation of GAGs affects retinal function. Bone marrow transplantation (BMT) is a relatively effective therapy for many lysosomal storage diseases and can result in a dramatic reduction in lysosomal distention in the RPE. Although effective at reducing lysosomal storage, it is not clear how effective syngeneic BMT is at treating retinal dysfunction. Here we show that there is a progressive decrease in the amplitudes of both the dark-adapted (rod-cone) and light-adapted (cone-dominated) flash electroretinograms (ERG) between 8 and 20 weeks of age in a murine model of mucopolysaccharidosis type VII (MPS VII). By 20 weeks, the average dark-adapted b-wave amplitude was 118 microV in MPS VII mice as compared to 469 microV in normal mice of the same strain. MPS VII mice receiving syngeneic BMT at 4 weeks of age have reduced lysosomal storage in retinal pigment epithelial cells and normal ERG amplitudes at 20 weeks of age. Retinal function is impaired in untreated 8 week old MPS VII mice. Following BMT at 8 weeks, rod-cone- and cone-dominated responses recovered to within the normal range by 20 weeks of age. These data demonstrate the temporal pattern of retinal dysfunction in the MPS VII mouse and indicate that BMT can reduce the lysosomal storage and improve retinal function.

A genetically myeloablated MPS VII model detects the expansion and curative properties of as few as 100 enriched murine stem cells.

Causes of transplantation failures are often difficult to assess due to our inability to monitor hematopoietic stem cell (HSC) homing, distribution, and amplification in situ. We have developed a mouse model that permits histochemical localization of 1000-fold enriched HSC and quantification of their long-term expanded progeny in situ. The mice are genetically myeloablated (c-kit receptor mutated, W41/W41) and are beta-glucuronidase null (GUSB ; gus(mps)/gus(mps)). The GUSB- mice with mucopolysaccharidosis type VII (MPS VII), like a large number of human patients with similar diseases, have systemic lysosomal storage disease that leads to premature death. Congenic GUSB+, Lineage(lo), Sca-1(hi), c-Kit(hi), Hoechst(lo) HSC, at doses of 30, 100, 250, and 425 cells, implanted and amplified in adult W41/W41, gus(mps)/gus(mps) recipients in a dose-dependent manner. At autopsy, primary recipients of 100 and 425 donor cells had histologically identifiable donor GUSB+ cells in multiple sites and showed both myeloid and lymphoid expansion in bone marrow. Donor cells were rare in the liver and spleen of 100-cell recipients, but lysosomal storage was significantly reduced. The life span was significantly extended in engrafted recipients of 250 (36.7 +/- 3.84 weeks,p = 0.0316) and 425 (40.7 +/-1.53 weeks,p = 0.0033) cells compared to untreated mice (26.4 +/- 1.53 weeks). Secondary hosts of marrow from the recipients of 425 cells demonstrated continued expansion of the GUSB+ cells. Results indicate the genetically myeloablated MPS VII mice can be used to trace and enumerate donor cells long-term and to follow early engraftment events in situ.

Behavior and therapeutic efficacy of beta-glucuronidase-positive mononuclear phagocytes in a murine model of mucopolysaccharidosis type VII.

Bone marrow transplantation (BMT) is relatively effective for the treatment of lysosomal storage diseases. To better understand the contribution of specific hematopoietic lineages to the efficacy of BMT, we transplanted beta-glucuronidase-positive mononuclear phagocytes derived from either the peritoneum or from bone marrow in vitro into syngeneic recipients with mucopolysaccharidosis type VII (MPS VII). Cell surface marking studies indicate that the bone marrow-derived cells are less mature than the peritoneal macrophages. However, both cell types retain the ability to home to tissues rich in cells of the reticuloendothelial system after intravenous injection into MPS VII mice. The half-life of both types of donor macrophages is approximately 7 days, and some cells persist for at least 30 days. In several tissues, therapeutic levels of beta-glucuronidase are present, and histopathologic analysis demonstrates that lysosomal storage is dramatically reduced in the liver and spleen. Macrophages intravenously injected into newborn MPS VII mice localize to the same tissues as adult mice but are also observed in the meninges and parenchyma of the brain. These data suggest that macrophages play a significant role in the therapeutic efficacy of BMT for lysosomal storage diseases and may have implications for treatments such as gene therapy.

Enzyme replacement therapy improves reproductive performance in mucopolysaccharidosis type VII mice but does not prevent postnatal losses.

Mice with mucopolysaccharidosis type VII (MPS VII) are devoid of beta-glucuronidase and accumulate glycosaminoglycans in lysosomes resulting in bone dysplasia, learning disabilities, and decreased mobility. MPS VII males do not breed and, while MPS VII females occasionally mate with heterozygous males, they do not maintain their young postnatally. Heterozygous matings produce less than 25% MPS VII offspring, but until now it was unclear whether this results from prenatal or postnatal losses. The administration of recombinant beta-glucuronidase from birth significantly reduces glycosaminoglycan storage in most tissues, increases life span, and improves the animal's cognitive ability and mobility. To determine whether reproductive failure is corrected by such therapy, male and female MPS VII mice were injected with enzyme at weekly intervals from birth to 5 wk of age (6xinj). Enzyme-replaced MPS VII mice bred when mated together. The 6xinj MPS VII males mated repeatedly until they were killed 135 d postinjection. All mated 6xinj MPS VII females gave birth to two litters, but maintained few of their young. Selective loss of MPS VII offspring was observed in matings between heterozygotes. Analysis of 379 preterm fetuses from heterozygous matings showed a frequency of 24.6% MPS VII pups, indicating that the decreased number of MPS VII pups produced by mating heterozygotes results from postnatal losses. The ovaries of young adult MPS VII mice have follicles and corpora lutea, and the testes generate sperm. Results suggest that the reproductive failure in MPS VII mice is related to impaired mobility and/or impaired cognitive function, and enzyme replacement restores mating capacity.

Enzyme replacement therapy for murine mucopolysaccharidosis type VII leads to improvements in behavior and auditory function.

Mucopolysaccharidosis type VII (MPS VII; Sly syndrome) is one of a group of lysosomal storage diseases that share many clinical features, including mental retardation and hearing loss. Lysosomal storage in neurons of the brain and the associated behavioral abnormalities characteristic of a murine model of MPS VII have not been shown to be corrected by either bone marrow transplantation or gene therapy. However, intravenous injections of recombinant beta-glucuronidase initiated at birth reduce the pathological evidence of disease in MPS VII mice. In this study we present evidence that enzyme replacement initiated at birth improved the behavioral performance and reduced hearing loss in MPS VII mice. Enzyme-treated MPS VII mice performed similarly to normal mice and significantly better than mock- treated MPS VII mice in every phase of the Morris Water Maze test. In addition, the auditory function of treated MPS VII mice was dramatically improved, and was indistinguishable from normal mice. These data indicate that some of the learning, memory, and hearing deficits can be prevented in MPS VII mice if enzyme replacement therapy is initiated early in life. These data also provide functional correlates to the biochemical and histopathological improvements observed after enzyme replacement therapy.

Toxoplasmic polymyositis revisited: case report and review of literature.

Toxoplasmosis can cause polymyositis either by reactivation or by recent infection. Inconsistent response to antiprotozoal therapy has been the strongest argument against toxoplasmic polymyositis as a separate entity. We report a biopsy-proven case of toxoplasmic polymyositis in a cardiac transplant patient presenting with a severe proximal weakness, myopathic, electromyographic changes and ten-fold increase of anti-Toxoplasma antibodies. An early antiprotozoal therapy and plasmapheresis led to recovery. A review of previously reported cases of toxoplasmic polymyositis suggests that an early antiprotozoal therapy is the most important variable affecting the outcome of this disease. We propose that toxoplasmic polymyositis has two phases: acute, responsive to antiprotozoal therapy, and chronic, manifested by altered immune response requiring steroids. We suggest that all patients presenting with polymyositis should have serological tests for toxoplasmosis as a part of their initial evaluation and an early trial of antiprotozoal therapy in case of positive findings.

Implantation and expansion of split-thickness skin grafts: a new source of prefabricated pedicle flaps and grafts.

The objective of this study was to determine whether a split-thickness skin graft can be implanted deep to the skin and whether it can be expanded. We also wanted to find out whether this implanted and expanded split-thickness skin graft can be used as a new source of skin grafts and as a pedicle flap. A tissue expander mounted on a Dacron sheet backing was specially designed for this experiment. Six female Hanford minipigs weighing 20 to 25 kg were operated on in three stages. In stage one, a split-thickness skin graft 0.03 in thick was harvested from the back, placed dermal side out over the expander, and sutured to the Dacron backing. The expander with the overlying split-thickness skin graft was then implanted deep to the panniculus carnosus muscle. Daily expansion was started 2 weeks after implantation to obtain a total volume of 1300 to 2500 cc. In the second stage, performed 4 to 6 weeks after implantation, the skin over the expander was elevated superficial to the panniculus carnosus muscle as a ventrally based flap, and the panniculus carnosus muscle was next elevated as a dorsally based flap lined on its deep surface with the implanted/expanded skin. Full-thickness skin grafts obtained from this implanted/expanded skin and from normal skin were transplanted to two 3 x 3 cm skin defects. The panniculus carnosus muscle implanted/expanded skin flap was then turned 180 degrees and sutured to a dorsally created skin defect. In the third stage, 4 weeks later, we noted the quality, texture, and appearance and obtained punch biopsies from normal skin, normal skin graft, implanted/expanded skin graft, and panniculus carnosus muscle implanted/expanded flap for histopathologic examination. All skin grafts "took" well, survived implantation, and were expanded successfully. The initial surface area of implanted split-thickness skin graft showed a net increase of 8 to 193 percent (mean percentage net increase 90 percent). This implanted/expanded skin also was retransplanted successfully to a skin defect. In all six minipigs, a skin-lined panniculus carnosus muscle implanted/expanded skin flap was constructed and survived transfer to an adjacent skin defect. The smallest flap of panniculus carnosus muscle implanted/expanded skin measured 10 x 12 cm and the largest 12 x 28 cm (mean surface area 228 cm2).

A clinical-pathological study of nonsurvivors of newborn ECMO.

Extracorporeal membrane oxygenation (ECMO) is an important means of supporting newborns with respiratory failure. While short- and long-term follow-up of ECMO survivors has been thoroughly addressed, there is no systematic study of nonsurvivors. Nineteen nonsurvivors of newborn ECMO with autopsy results are divided into two groups: group 1: 12 patients who had intracranial lesions as the primary cause of death (hemorrhage 8, encephalomalacia 2, infarct 2); and group 2: 7 patients with nonintracranial primary causes of death. Patients in group 1 were significantly more acidotic, hypotensive, and smaller in age and birth weight pre-ECMO. Among group 2 patients, two with diaphragmatic hernia died of primary pulmonary disease (diffuse alveolar damage, pulmonary hypoplasia and necrosis, bronchopneumonia). One of 2 patients with persistent fetal circulation (PFC) was treated with massive doses of tolazoline and suffered fatal gastrointestinal hemorrhage and ischemic necrosis of heart, spleen, testes, and adrenals. The other PFC patient had severe pulmonary interstitial fibrosis. Two patients with meconium aspiration and a patient with streptococcal sepsis had diffuse pulmonary damage and multiple organ failure (renal medullary necrosis, and infarcts of adrenal, spleen, liver). In this series, intracranial pathology was the most common cause of death in ECMO patients, related to gestational age, acidosis, hypoxia, and size, but probably unrelated to carotid ligation.

Reversal of pathology in murine mucopolysaccharidosis type VII by somatic cell gene transfer.

An inherited deficiency of beta-glucuronidase in humans, mice and dogs causes mucopolysaccharidosis VII (Sly syndrome), a progressive degenerative disease that reduces lifespan (to an average of 5 months in mice) and results from lysosomal storage of undegraded glycosaminoglycans in the spleen, liver, kidney, cornea, brain and skeletal system. Bone marrow transplantation in mutant mice provides a source of normal enzyme ('cross-correction'), which substantially improves the clinical condition and extends the average lifespan to 18 months. Gene therapy by transfer of a beta-glucuronidase gene into mutant haematopoietic stem cells is an alternative approach, but it is not known whether the low expression of vector-transferred genes in vivo would be sufficiently effective. Here we show that retroviral vector-mediated transfer of the gene to mutant stem cells results in long-term expression of low levels of beta-glucuronidase which partially corrects the disease by reducing lysosomal storage in liver and spleen.

Valproate use associated with persistent hyperammonemia and mitochondrial injury in a child with Down's syndrome.

Valproate is a commonly prescribed anticonvulsant drug that may cause potentially fatal hepatotoxicity, bone-marrow toxicity, and pancreatitis. Toxicity usually resolves, though, after discontinuation of the medication. We report a 9-year-old boy who had Down's syndrome and who developed valproate-associated bone marrow toxicity, and hepatotoxicity that persisted greater than 2 years after discontinuation of valproate therapy. Three years after starting valproate, he developed erythrocyte aplasia with a severe, normochromic, macrocytic anemia requiring several blood transfusions. Several months later while still receiving valproate, he developed progressive hyperammonemia and decreased hepatic synthetic function. The macrocytic anemia resolved and hepatic synthetic function improved after discontinuation of valproate therapy. However, hyperammonemia, steatosis, mitochondrial injury, and marked hepatic iron accumulation persisted greater than 2 years after the valproate was discontinued. The persistent hyperammonemia was responsive to lactulose therapy. A decrease in hepatic iron content by serial phlebotomies did not result in any improvement in the hyperammonemia or hepatic synthetic function. This is the first report of persistent hyperammonemia and hepatic mitochondrial injury after valproic acid therapy.

Increased life span and correction of metabolic defects in murine mucopolysaccharidosis type VII after syngeneic bone marrow transplantation.

The gusmps/gusmps mouse has no beta-glucuronidase activity and develops murine mucopolysaccharidosis type VII (MPS VII). The clinical and pathologic abnormalities are similar to those found in humans with severe MPS VII. Mutant mice are dysmorphic, dwarfed, and have a shortened life span. Pathologic findings include widespread lysosomal storage. To determine whether bone marrow transplantation (BMT) corrects these abnormalities, genetically identical mutant animals were given syngeneic bone marrow transplants using cells from +/+ mice. Initial experiments showed that levels of beta-glucuronidase activity in recipient tissues correlated with the amount of radiation administered before BMT. Two groups of mice given BMT therapy were observed for periods of 1 and 2 years, respectively. These mice were evaluated using a combination of clinical, biochemical, histochemical, and pathologic analyses. Spleen, liver, cornea, and glomerular mesangial cells showed essentially complete correction at all radiation doses. Storage was partially corrected in meninges and perivascular cells in brain, and in renal tubular epithelial cells at the higher radiation doses. Life span in BMT-treated animals was increased approximately three-fold, approaching that seen in normal mice after BMT. These results support the position that BMT has a place in the therapeutic regimen for MPS VII.