Coronary artery patency following long-term successful engraftment 14 years after bone marrow transplantation in the Hurler syndrome

Persistent bone and joint disease despite current treatments for mucopolysaccharidosis types I, II, and VI: Data from a 10-year prospective study

The mucopolysaccharidosis (MPS) disorders have many potential new therapies on the horizon. Thus, historic control data on disease progression and variability are urgently needed. We conducted a 10-year prospective observational study of 55 children with MPS IH (N = 23), MPS IA (N = 10), non-neuronopathic MPS II (N = 13), and MPS VI (N = 9) to systematically evaluate bone and joint disease. Annual measurements included height, weight, and goniometry. Mixed effects modeling was used to evaluate changes over time. All participants had been treated with hematopoietic cell transplantation and/or enzyme replacement therapy. Height z-score decreased over time in MPS IH, MPS II, and MPS VI, but not MPS IA. Adult heights were 136 ± 10 cm in MPS IH, 161 ± 11 cm in MPS IA, 161 ± 14 cm in MPS II, and 128 ± 15 cm in MPS VI. Adult average BMI percentiles were high: 75 ± 30%ile in MPS IH, 71 ± 37%ile in MPS IA, 71 ± 25%ile in MPS II, and 60 ± 42%ile in MPS VI. Every participant had joint contractures of the shoulders, elbows, hips, and/or knees. Joint contractures remained stable over time. In conclusion, despite current treatments for MPS I, II, and VI, short stature and joint contractures persist. The elevation in average BMI may be related, in part, to physical inactivity due to the ongoing bone and joint disease. Data from this longitudinal historical control study may be used to expedite testing of experimental bone and joint directed therapies and to highlight the need for weight management as part of routine clinical care for patients with MPS.

Identification of a novel fusion Iduronidase with improved activity in the cardiovascular system

Background

Lysosomal diseases are a group of over 70 rare genetic conditions in which a protein deficiency (most often an enzyme deficiency) leads to multi-system disease. Current therapies for lysosomal diseases are limited in their ability to treat certain tissues that are major contributors to morbidity and mortality, such as the central nervous system (CNS) and cardiac valves. For this study, the lysosomal disease mucopolysaccharidosis type I (MPS I) was selected as the disease model. In MPS I, mutations in the IDUA gene cause a deficiency of the α-L-iduronidase (IDUA) enzyme activity, leading to disease pathology in tissues throughout the body, including the CNS and cardiac valves. Current therapies have been unable to prevent neurodevelopmental deficits and cardiac valvular disease in patients with MPS I. This study aimed to evaluate the delivery of IDUA enzyme, via a novel gene therapy construct, to target tissues.

Methods

MPS I mice were hydrodynamically injected through the tail vein with plasmids containing either a codon-optimized cDNA encoding the wild-type IDUA protein or one of four modified IDUAs under the control of the liver-specific human α1-antitrypsin (hAAT) promoter. Two modified IDUAs contained a ligand for the CB1 receptor, which is a highly expressed receptor in the CNS. Iduronidase activity levels were measured in the tissues and plasma using an enzyme activity assay.

Results

The modified IDUAs did not appear to have improved activity levels in the brain compared with the unmodified IDUA. However, one modified IDUA exhibited higher activity levels than the unmodified IDUA in the heart (p = 0.0211). This modified iduronidase (LT-IDUA) contained a sequence for a six amino acid peptide termed LT. LT-IDUA was further characterized using a noncompartmental pharmacokinetic approach that directly analyzed enzyme activity levels after gene delivery. LT-IDUA had a 2-fold higher area under the curve (AUC) than the unmodified IDUA (p = 0.0034) when AUC was estimated using enzyme activity levels in the plasma.

Conclusion

The addition of a six amino acid peptide improved iduronidase's activity levels in the heart and plasma. The short length of this LT peptide facilitates its use as fusion enzymes encoded as gene therapy or administered as enzyme replacement therapy. More broadly, the LT peptide may aid in developing therapies for numerous lysosomal diseases.

Mucopolysaccharidosis Type I: Current Treatments, Limitations, and Prospects for Improvement

Mucopolysaccharidosis type I (MPS I) is a lysosomal disease, caused by a deficiency of the enzyme alpha-L-iduronidase (IDUA). IDUA catalyzes the degradation of the glycosaminoglycans dermatan and heparan sulfate (DS and HS, respectively). Lack of the enzyme leads to pathologic accumulation of undegraded HS and DS with subsequent disease manifestations in multiple organs. The disease can be divided into severe (Hurler syndrome) and attenuated (Hurler-Scheie, Scheie) forms. Currently approved treatments consist of enzyme replacement therapy (ERT) and/or hematopoietic stem cell transplantation (HSCT). Patients with attenuated disease are often treated with ERT alone, while the recommended therapy for patients with Hurler syndrome consists of HSCT. While these treatments significantly improve disease manifestations and prolong life, a considerable burden of disease remains. Notably, treatment can partially prevent, but not significantly improve, clinical manifestations, necessitating early diagnosis of disease and commencement of treatment. This review discusses these standard therapies and their impact on common disease manifestations in patients with MPS I. Where relevant, results of animal models of MPS I will be included. Finally, we highlight alternative and emerging treatments for the most common disease manifestations.

An online survey on burden of illness among families with post-stem cell transplant mucopolysaccharidosis type I children in the United States

Background

Severe mucopolysaccharidosis type I (also known as Hurler syndrome) is a rare devasting recessive genetic disease caused by the deficiency of an enzyme. Hematopoietic stem cell transplant is the standard of care in the United States, usually conducted before the child is 3 years of age, but little is known about the continued medical and educational needs of the child after transplant. A greater understanding of the burden of illness on the primary caregiver is also needed. Therefore, this online survey sought to gather information on the burden of severe MPS I in the United States at least 1 year after transplant.

Results

Thirty-two respondents reported that children with severe MPS I have significant medical and educational needs after transplant. Healthcare resource use was frequent, especially in the outpatient setting specifically for bone, cardiac, and vision complications that were not relieved by HSCT. Twenty-five percent of the children had been hospitalized at least once in the last year and two had been hospitalized twice. The most common reasons for overnight hospitalizations included orthopedic surgeries and respiratory infections. Among children ages 5 and older, only 3 of 28 (11%) were able to attend school with no special support. While caregivers were generally satisfied with the healthcare services their child receives, 69% of working caregivers reported negative impact on their ability to conduct work tasks, and 54% of caregivers did not work so that they could care for the child.

Conclusions

Results suggest that severe MPS I children continue to  require medical care and special support for education. Future research on the burden of illness on families affected by severe MPS I is needed to better understand total cost of care, and to identify therapies and interventions that reduce burden of illness. Future studies that compare cost of and access to health care in different countries may provide a more global view of the burden of MPS I.

The factors affecting lipid profile in adult patients with Mucopolysaccharidosis

Background

Mucopolysaccharidoses (MPS) are a group of rare inherited disorders characterized by abnormal accumulation of glycosaminoglycans (GAGs) within the myocytes and coronary arteries. Little is known about hyperlipidaemia as a potential cardiovascular risk factor in these patients. Baseline cholesterol data in adults are scarce. Therefore, the aim of this study was to analyse factors affecting lipid profile in different types of MPSs to determine if abnormalities in lipid profile contribute to the overall risk of cardiovascular disease.

Methods

Adult patients (above the age of 16) with MPS type I, II, III, IV and VI attending clinics in two Inherited Metabolic Disorders centres were included. Their lipid profile, lipoprotein (a), HbA1c, Glucose Tolerance Test (GTT), BMI and treatment type were extracted. Analysis included descriptive statistics and Student t-test.

Results

Eighty two patients with five MPS types (I, II, III, IV and VI) were included in the study; 29 were females (35%) and 53 were males (65%). BMI above 25 kg/m² in all MPS types indicated that some patients were overweight for their height. Only one patient post-HSCT had diabetes. In 3 cases insulin was analysed during GTT and showed no insulin resistance despite raised BMI. Mean total cholesterol and LDL-cholesterol were below 5 mmol/L and 3 mmol/L, respectively, in five individual MPS types. Lipoprotein (a) was available for 6 MPS IV patients and was not significantly raised.

Conclusions

MPS disorders are not associated with significant hypercholesterolaemia or diabetes mellitus despite increased BMI. Total cholesterol and LDL-cholesterol were within the targets for primary prevention for non-MPS population. Lipoprotein (a) is not a useful marker of cardiovascular disease in a small group of adult MPS IV patients irrespectively of treatment option. Whether long-term cardiovascular risk is dependent on lipid profile, diabetes, obesity or GAGs deposition within the organ system remains unanswered.

Elevated TNF-α is associated with pain and physical disability in mucopolysaccharidosis types I, II, and VI

BACKGROUND

Children and adults with the lysosomal storage diseases mucopolysaccharidosis (MPS) types I, II and VI live shortened lives permeated by chronic pain and physical disability. Current treatments do not alleviate these problems. Thus there is a critical need to understand the mechanism of chronic pain and disability in MPS in order to improve the way we treat patients. A potential target is inflammation.

HYPOTHESIS

We hypothesized that excessive inflammation mediated by the tumor necrosis factor-α (TNF-α) inflammatory pathway is the fundamental cause of much of the chronic pain and physical disability in MPS.

METHODS

55 patients with MPS I, II, or VI were enrolled over the course of a 5-year prospective longitudinal natural history study and evaluated annually for 2-5years. 51 healthy controls were enrolled in a separate cross-sectional study of bone and energy metabolism. TNF-α was measured by ELISA. Pain and physical disability were measured by the Children's Health Questionnaire - Parent Form 50 (CHQ-PF50). Differences in log-transformed TNF-α levels and associations with CHQ domains were evaluated using a linear mixed effects model with random intercept.

RESULTS

TNF-α levels were measured in 48 MPS (age: 5-17years; 35% female) and 51 controls (age: 8-17years; 53% female). Among MPS, 22 (46%) were treated with hematopoietic cell transplantation (HCT) alone, 24 (50%) with enzyme replacement therapy (ERT) alone, and 2 (4%) with both HCT and ERT. TNF-α levels are higher in MPS compared to healthy controls (p<0.001). Higher TNF-α levels are associated with increased pain and decreased physical function, social limitations due to physical health, and physical summary score (all p<0.05). TNF-α levels were not significantly associated with the general health score. TNF-α levels did not change significantly over time in MPS.

CONCLUSIONS

Higher TNF-α levels are implicated in the pain and decreased physical function present in individuals with MPS despite treatment with ERT and/or HCT, suggesting that TNF-a inhibition could potentially be a useful adjunctive therapy. Further investigation into the role of TNF-α inhibition in MPS to decrease pain and improve physical function is indicated.

Carotid intima-media thickness is increased in patients with treated mucopolysaccharidosis types I and II, and correlates with arterial stiffness

BACKGROUND

Treatments for mucopolysaccharidoses (MPSs) have increased longevity, but coronary artery disease (CAD) and cardiovascular complications cause mortality in a high percentage of patients. Non-invasive measures of sub-clinical atherosclerosis, such as carotid intima-media thickness (cIMT) and arterial stiffness, may be useful for prediction of CAD outcomes in MPS patients.

OBJECTIVES

The aim of the study was to determine if cIMT and arterial stiffness are abnormal in MPS I and II patients compared to healthy controls.

METHODS

MPS patients underwent carotid artery ultrasonography, and electronic wall-tracking software was used to measure cIMT, carotid artery cross-sectional compliance (cCSC), cross-sectional distensibility (cCSD), and incremental elastic modulus (cIEM). Control data from healthy subjects were obtained from a different study that utilized identical testing within the same laboratory.

RESULTS

A total of 406 healthy controls and 25 MPS patients (16 MPS I, 9 MPS II) were studied. All MPS patients had or were receiving treatment: 15 patients (6 MPS I, 9 MPS II) were receiving enzyme replacement therapy (ERT), 9 patients (all MPS I) had received hematopoietic stem cell transplant (HSCT), and 1 patient with MPS I had received HSCT and was receiving enzyme replacement therapy (ERT). MPS patients had significantly higher mean (± SD) cIMT (0.56 ± 0.05 mm) compared to controls (0.44 ± 0.04 mm; adjusted p<0.001). MPS patients also had increased stiffness compared to controls, showing significantly lower cCSC (0.14 ± 0.09 mm(2)/mmHg versus 0.16 ± 0.05 mm(2)/mmHg; adjusted p=0.019), and higher cIEM (1362 ± 877 mmHg versus 942 ± 396 mmHg; adjusted p<0.001). cCSD in MPS patients was lower than that of controls (29.7 ± 16.4% versus 32.0 ± 8.2%) but was not statistically significant; p=0.12. Among MPS patients, cCSD showed a significant association with cIMT (p=0.047), while the association between cIEM and cIMT approached significance (p=0.077). No significant differences were observed in cIMT, cCSD, cCSC, and cIEM between MPS I and MPS II patients.

CONCLUSIONS

Despite treatment, MPS patients had higher cIMT compared to healthy controls, indicating this marker of sub-clinical atherosclerosis may be a useful predictor of CAD outcomes. The association of arterial stiffness measures with cIMT suggests that mechanical and structural changes may occur in concert among MPS patients. Although yet to be confirmed, increased cIMT and arterial stiffness in MPS I and II patients may be a consequence of inflammatory signaling pathways triggered by heparan or dermatan sulfate-derived oligosaccharides. Prospective, longitudinal studies will need to be performed in order to evaluate the usefulness of these carotid measurements as predictors of adverse CAD outcomes in MPS patients.

Unexpected coronary artery findings in mucopolysaccharidosis. Report of four cases and literature review

INTRODUCTION

The mucopolysaccharidosis syndromes are a group of lethal inherited disorders affecting multiple organ systems by the progressive deposition of glycosaminoglycan. Advances in treatment such as enzyme replacement and hematopoietic stem cell transplantation have significantly improved the outcome of these disorders. An in-depth understanding of the pathophysiology of heart disease in these disorders is essential since death from cardiac causes continues to be common. Epicardial coronary artery luminal narrowing from myointimal proliferation and glycosaminoglycan deposition is well described in severe mucopolysaccharidosis type I [Hurler syndrome, mucopolysaccharide IH] but poorly understood in other "non-Hurler" phenotypes of these disorders. Given the rarity of these conditions, autopsy specimens are uncommon.

METHODS

Tissue from epicardial coronary arteries from autopsies of four patients with non-Hurler mucopolysaccharidosis (attenuated type I, type IIIA, type IIIC, and type VI) who had died after hematopoietic cell transplantation (within 1 month in three cases; after 5 years in the fourth) was examined by light microscopy.

RESULTS

Unexpectedly, near-normal coronary arteries were observed in the patient with attenuated mucopolysaccharidosis type I, while the coronaries from patients with type IIIA, IIIC, and VI demonstrated classic histologic features of glycosaminoglycan deposition. The most severe findings were found in the MPS IIIC patient who had 5 years of full donor engraftment after transplantation.

CONCLUSIONS

Our current understanding of the cardiac manifestations of the mucopolysaccharidoses fails to explain why near-normal coronary arteries may be observed when abnormalities would be most likely to be expected and, conversely, why significant histopathology is present when it would be least expected. Identification of downstream effects of glycosaminoglycan deposition may identify other metabolites or metabolic pathways that are important in the clinicopathologic manifestations of these diseases.

SUMMARY

The mucopolysaccharidosis diseases are a group of inherited disorders affecting multiple organ systems by the progressive deposition of glycosaminoglycan. Severe coronary artery disease is well recognized in severe type I mucopolysaccharidosis (Hurler syndrome), but unexpected coronary artery disease occurs in other, "non-Hurler" mucopolysaccharidoses. Factors responsible for the development of coronary pathology in the mucopolysaccharidoses remain elusive.

Endothelial function in children and adolescents with mucopolysaccharidosis

BACKGROUND

Although coronary artery pathology is a prominent feature of mucopolysaccharidosis (MPS), it may be underestimated by coronary angiography because of its diffuse nature. It is also generally assumed that cardiovascular risk is increased in MPS and reduced following hematopoietic stem cell transplantation (HSCT) or enzyme replacement therapy (ERT), but this has never been formally evaluated. Non-invasive methods of assessing vascular endothelial function may provide a measure of cardiovascular risk in MPS. We evaluated endothelial function, using digital reactive hyperemia, in youth with MPS and in healthy controls.

METHODS

Digital reactive hyperemic index (RHI) was measured in 12 children and adolescents (age 10.3 ± 3.9 years old; 11 boys) with treated MPS and nine age- and gender-matched (11.4 ± 4.0; 8 boys) healthy controls. An independent t-test was used to compare RHI between individuals with MPS and controls.

RESULTS

Children and adolescents with MPS (MPS type II: N = 5; type I: N = 4; type VI: N = 3) whether treated by HSCT (N = 4) or ERT (N = 8) had significantly lower RHI compared to controls (MPS 1.22 ± 0.19 vs. controls 1.46 ± 0.32, p < 0.05).

CONCLUSION

These preliminary findings suggest that children and adolescents with treated MPS have significantly poorer endothelial function when compared to healthy controls. Further investigation into the utility of endothelial function for risk stratification and the long term implications of reduced endothelial function in MPS is warranted.

Carotid intima-media thickness is increased in patients with mucopolysaccharidoses

BACKGROUND

The feasibility of carotid artery intima-media thickness (C-IMT), an established cardiovascular disease marker, as a cardiac risk marker in mucopolysaccharidosis (MPS) patients was explored.

OBJECTIVES

To determine if C-IMT is abnormal in MPS versus unaffected controls, and if C-IMT correlates with coronary artery diameter in MPS.

MATERIAL AND METHODS

Measurements of C-IMT via neck ultrasound and echocardiographic parameters, including coronary artery diameters, were obtained from MPS and control patients, and compared.

RESULTS

Sixteen MPS subjects (6 MPS I, 6 MPS II, 2 MPS III, 1 MPS VI, 1 MPS VII) and sixteen age, ethnicity, and gender-matched controls were enrolled. Median MPS and control subject ages were 8.3±4.5 and 8.6±4.3 years, respectively (p=0.73). Mean MPS and control C-IMTs were 0.54±0.070 and 0.48±0.034 mm (p=0.0029). No differences in left main, left anterior descending, or right coronary artery diameters were seen between MPS and controls. A significant proportion of MPS subjects had mitral insufficiency (14/16; p=0.0002), aortic insufficiency (10/16; p=0.0021), and left ventricular dilatation (7/16, p=0.037) versus controls. C-IMT did not correlate significantly with age, height, weight, coronary measurements, or duration of treatment.

CONCLUSION

C-IMT in MPS patients is increased compared to matched controls, likely reflective of arterial intima-medial glycosaminoglycan accumulation. MPS subjects demonstrated a high percentage of left-sided valvular insufficiency and ventricular dilatation. Additional studies should be performed in MPS patients to determine if C-IMT correlates with arterial elasticity, biomarkers of vascular dysfunction, and higher risk of cardiovascular events.

Cardiac disease in patients with mucopolysaccharidosis: presentation, diagnosis and management

The mucopolysaccharidoses (MPSs) are inherited lysosomal storage disorders caused by the absence of functional enzymes that contribute to the degradation of glycosaminoglycans (GAGs). The progressive systemic deposition of GAGs results in multi-organ system dysfunction that varies with the particular GAG deposited and the specific enzyme mutation(s) present. Cardiac involvement has been reported in all MPS syndromes and is a common and early feature, particularly for those with MPS I, II, and VI. Cardiac valve thickening, dysfunction (more severe for left-sided than for right-sided valves), and hypertrophy are commonly present; conduction abnormalities, coronary artery and other vascular involvement may also occur. Cardiac disease emerges silently and contributes significantly to early mortality.The clinical examination of individuals with MPS is often difficult due to physical and, sometimes, intellectual patient limitations. The absence of precordial murmurs does not exclude the presence of cardiac disease. Echocardiography and electrocardiography are key diagnostic techniques for evaluation of valves, ventricular dimensions and function, which are recommended on a regular basis. The optimal technique for evaluation of coronary artery involvement remains unsettled.Standard medical and surgical techniques can be modified for MPS patients, and systemic therapies such as hematopoietic stem cell transplantation and enzyme replacement therapy (ERT) may alter overall disease progression with regression of ventricular hypertrophy and maintenance of ventricular function. Cardiac valve disease is usually unresponsive or, at best, stabilized, although ERT within the first few months of life may prevent valve involvement, a fact that emphasizes the importance of early diagnosis and treatment in MPS.

Fatal coronary artery disease in an infant with severe mucopolysaccharidosis type I

A previously healthy 10-month-old boy was referred to our hospital because of coarse facial features that were suggestive of lysosomal storage disease. Apart from noisy respiration, there was no medical history. Elevated levels of urinary glycosaminoglycans and complete deficiency of leukocyte α-l-iduronidase indicated severe mucopolysaccharidosis type I. A chest radiograph revealed a markedly enlarged heart, and echocardiography revealed hypertrophic cardiomyopathy. While hematopoietic stem cell transplantation was being planned, progressive cardiac failure developed with a striking hypokinesia of the left-ventricle free wall. In combination with ischemic changes on the electrocardiogram, this was suggestive of coronary artery disease. Results of coronary echo Doppler interrogation were inconclusive, and intravascular ultrasound in this little infant was not feasible. Despite the patient's small size, a successful selective coronary angiography was performed and revealed diffuse narrowing of the left coronary artery with collateral flow from the right coronary artery. Enzyme-replacement therapy was started immediately in an attempt to improve myocardial performance. Evaluation after 3 months, however, revealed complete obliteration of the left coronary main stem with diffuse hypokinesia/akinesia of the left ventricle. At the age of 13 months the boy died of terminal cardiac failure. This case report illustrates the importance of considering early development of coronary artery disease in children with severe mucopolysaccharidosis type I and cardiomyopathy.

Growth patterns and the use of growth hormone in the mucopolysaccharidoses

Short stature is characteristic of patients with mucopolysaccharidosis (MPS) diseases. For children with skeletal dysplasias, such as MPS, it is important to know the natural history of growth. An understanding of the natural growth pattern in each MPS disease provides a measurement to which treatments can be compared, as well as data which can help families and providers make individualized decisions about growth promoting treatments. Multiple advancements have been made in the treatment of MPS with both hematopoietic cell transplantation (HCT) and enzyme replacement therapy (ERT). The long term benefit of these treatments on growth is unknown. This article will review the published data on growth in children with MPS, and describe preliminary data on the use of human growth hormone (hGH) in children with MPS.

Scheie syndrome: enzyme replacement therapy does not prevent progression of cervical myelopathy due to spinal cord compression

Hurler-Scheie syndrome is caused by alpha-l-iduronidase deficiency. Enzyme replacement therapy (ERT) can improve physical capacity and reduces organomegaly. However, the effect on bradytrophic connective tissue is limited. As intravenously administered enzyme cannot cross the blood-brain barrier, the therapy of choice for the more severe Hurler syndrome is haematopoietic stem cell transplantation (HCT). In the more attenuated Scheie syndrome, neurological impairment is less severe; therefore, ERT may be appropriate to treat these patients. Information on long-term outcome in Scheie patients undergoing ERT is scarce. We report a 38-year-old female Scheie patient who has been on ERT for 8 years. While non-neurological symptoms improved, she developed paresthesias in her hands and feet and progressive pain in her legs. Somatosensory evoked potentials were abnormal, suggesting dysfunction of the dorsal funiculus and lemniscus medialis. After 6 years of ERT, a spinal MRI showed dural thickening at the upper cervical spine. These soft-tissue deposits are presumably due to the accumulation of mucopolysaccharides. Intramedullary hyperintensities at the level of C1/2 revealed cervical myelopathy. An MRI before the start of ERT had shown milder spinal lesions. Cystic lesions in the white matter of the centrum semiovale due to dilated Virchow-Robin spaces were essentially unchanged compared with the MRI scan before ERT. Decompression of the spinal cord resulted in clinical improvement. In an adult patient with Scheie syndrome, ERT failed to prevent progression of cervical myelopathy. Clinical significance of cerebral changes is unclear. Whether early HCT or intrathecal ERT could have prevented these lesions remains speculative.

Successful treatment of the murine model of cystinosis using bone marrow cell transplantation

Cystinosis is an autosomal recessive metabolic disease that belongs to the family of lysosomal storage disorders. The defective gene is CTNS encoding the lysosomal cystine transporter, cystinosin. Cystine accumulates in every organ in the body and leads to organ damage and dysfunction, including renal defects. Using the murine model for cystinosis, Ctns(-/-) mice, we performed syngeneic bone marrow cell (BMC), hematopoietic stem cell (HSC), and mesenchymal stem cell transplantation. Organ-specific cystine content was reduced by 57% to 94% in all organs tested in the BMC-treated mice. Confocal microscopy and quantitative polymerase chain reaction revealed a large quantity of transplanted BMC in all organs tested, from 5% to 19% of the total cells. Most of these cells were not from the lymphoid lineage but part of the intrinsic structure of the organ. The natural progression of renal dysfunction was prevented, and deposition of corneal cystine crystals was significantly improved in the BMC-treated mice. HSC had the same therapeutic effect as whole BMC. In contrast, mesenchymal stem cell did not integrate efficiently in any organ. This work is a proof of concept for using HSC transplantation as a therapy for cystinosis and highlights the efficiency of this strategy for a chronic, progressive degenerative disease.

The natural course and the impact of therapies of cardiac involvement in the mucopolysaccharidoses

OBJECTIVE

To analyze cardiac involvement and its progression in mucopolysaccharidoses, and to assess the short term impact of new therapeutic strategies.

PATIENTS AND METHODS

We studied echocardiographically 57 patients with various types of mucopolysaccharidoses, specifically types I, II, III, IV and VI, with a median age at the diagnosis of cardiac involvement of 5 years, following them for a median of 4.6 years, with a range from 0.9 to 21.2 years. We used a scoring system, along with the so-called delta score, to quantify the severity of involvement at baseline and at last examination, and to chart their progression over time.

RESULTS

Cases with cardiac involvement increased from 59.6% to 87.3% at the last examination. The scores increased with age, and were significantly different according to the specific type of mucopolysaccharidosis. Involvement of the mitral valve was most common, often associated with an aortic valvar anomaly and/or left ventricular hypertrophy. Patients with the first and second types had more severe involvement than those with the third or fourth types. Patients undergoing transplantation of haematopoietic stem cells seem to stabilize after an initial worsening while, in contrast, we were unable to demonstrate an effect of enzyme replacement therapy on the progression of the cardiac disease, possibly because those receiving such treatment had a higher median age, more severe cardiac disease and shorter follow-up.

CONCLUSIONS

Cardiac involvement was present early in more than a half of the patients identified as having mucopolysaccharidosis, and generally progressed, being more frequent and severe in the first and second types of the disease. Longer follow-up is needed to demonstrate any significant improvement induced by new therapies.

Mucopolysaccharidosis I: management and treatment guidelines

OBJECTIVE

Disease management for mucopolysaccharidosis type I has been inconsistent because of disease rarity (approximately 1 case per 100,000 live births), phenotypic heterogeneity, and limited therapeutic options. The availability of hematopoietic stem cell transplantation and the recent introduction of enzyme replacement therapy for mucopolysaccharidosis I necessitate the establishment of system-specific management guidelines for this condition.

METHODS

Twelve international experts on mucopolysaccharidosis I met in January 2003 to draft management and treatment guidelines for mucopolysaccharidosis I. Initial guidelines were revised and updated in 2008, on the basis of additional clinical data and therapeutic advances. Recommendations are based on our extensive clinical experience and a review of the literature.

RESULTS

All patients with mucopolysaccharidosis I should receive a comprehensive baseline evaluation, including neurologic, ophthalmologic, auditory, cardiac, respiratory, gastrointestinal, and musculoskeletal assessments, and should be monitored every 6 to 12 months with individualized specialty assessments, to monitor disease progression and effects of intervention. Patients are best treated by a multidisciplinary team. Treatments consist of palliative/supportive care, hematopoietic stem cell transplantation, and enzyme replacement therapy. The patient's age (>2 years or < or =2 years), predicted phenotype, and developmental quotient help define the risk/benefit profile for hematopoietic stem cell transplantation (higher risk but can preserve central nervous system function) versus enzyme replacement therapy (low risk but cannot cross the blood-brain barrier).

CONCLUSION

We anticipate that provision of a standard of care for the treatment of patients with mucopolysaccharidosis I will optimize clinical outcomes and patients' quality of life.

Outcomes of hematopoietic stem cell transplantation for Hurler's syndrome in Europe: a risk factor analysis for graft failure

Hurler's syndrome (HS), the most severe form of mucopolysaccharidosis type-I, causes progressive deterioration of the central nervous system and death in childhood. Allogeneic stem cell transplantation (SCT) before the age of 2 years halts disease progression. Graft failure limits the success of SCT. We analyzed data on HS patients transplanted in Europe to identify the risk factors for graft failure. We compared outcomes in 146 HS patients transplanted with various conditioning regimens and grafts. Patients were transplanted between 1994 and 2004 and registered to the European Blood and Marrow Transplantation database. Risk factor analysis was performed using logistic regression. ‘Survival’ and ‘alive and engrafted’-rate after first SCT was 85 and 56%, respectively. In multivariable analysis, T-cell depletion (odds ratio (OR) 0.18; 95% confidence interval (CI) 0.04–0.71; P=0.02) and reduced-intensity conditioning (OR 0.08; 95% CI 0.02–0.39; P=0.002) were the risk factors for graft failure. Busulfan targeting protected against graft failure (OR 5.76; 95% CI 1.20–27.54; P=0.028). No difference was noted between cell sources used (bone marrow, peripheral blood stem cells or cord blood (CB)); however, significantly more patients who received CB transplants had full-donor chimerism (OR 9.31; 95% CI 1.06–82.03; P=0.044). These outcomes may impact the safety/efficacy of SCT for ‘inborn-errors of metabolism’ at large. CB increased the likelihood of sustained engraftment associated with normal enzyme levels and could therefore be considered as a preferential cell source in SCT for ‘inborn errors of metabolism’.

Cardiac findings after enzyme replacement therapy for mucopolysaccharidosis type I

Mucopolysaccharidosis type I is a lethal autosomal recessive storage disease caused by a deficiency of lysosomal alpha-L-iduronidase and the consequent systemic accumulation of glycosaminoglycan. Cardiomyopathy and valvar insufficiency occur as glycosaminoglycan accumulates in the myocardium, expands the spongiosa of cardiac valves, and proliferates within the myointima of the epicardial coronary arteries. Congestive heart failure and death occur within the first decade of life in the most severe cases. Allogeneic hematopoietic stem cell transplantation, used in severe forms of the disease, markedly prolongs survival, alleviates ventricular hypertrophy, and preserves cardiac function, but cardiac valves continue to thicken and valvular insufficiency progresses. Enzyme replacement therapy with human recombinant alpha-L-iduronidase has been proposed as an alternativee therapy for patients with mucopolysaccharidosis type I in whom the risk/benefit ratio of hematopoietic stem cell transplantation seems unfavorable. The investigators report the cardiac findings in a small series of 5 children with mucopolysaccharidosis type I who received enzyme replacement therapy for as long as 7 years. No deaths occurred during treatment. Left ventricular hypertrophy, which was present before therapy, resolved in all cases, and myocardial function remained normal. In contrast, the mitral and aortic valves remained thickened and, in some instances, developed progressive thickening and regurgitation. In conclusion, long-term enzyme replacement therapy has some clear benefits for the myocardium, but the cardiac valves appear unresponsive, and the ultimate effect on the coronary vasculature is unknown.

Bone marrow transplantation for lysosomal storage disorders

Bone marrow transplantation for lysosomal storage disorders has been used for the past 25 years. The early allure of a promising new therapy has given way to more realistic expectations, as it has become clear that bone marrow transplantation is not a cure, but merely ameliorates the clinical phenotype. The results in some disorders are more acceptable than in others. Significant challenges have emerged, particularly the poor mesenchymal and neurological responses. Important recent advances in lysosomal biology, both in health and disease, have helped us to better understand the results of bone marrow transplantation, and to rationalize its role in the treatment of lysosomal storage disorders alongside newer therapies. At the same time, they have helped researchers to explore new therapeutic applications of bone marrow cells, such as gene and stem cell therapy.

Trends in haematopoietic cell transplantation for inborn errors of metabolism

For the last 25 years, haematopoietic cell transplantation (HCT) has been used as effective therapy for selected inborn errors of metabolism (IEMs), mainly lysosomal storage diseases and peroxisomal disorders. The main rational for HCT in IEMs is based on the provision of correcting enzymes by donor cells within and outside the blood compartment. The ultimate goal of HCT is to achieve a normal or near-normal life and normal neurodevelopment. HCT has been performed for more than 20 diseases. Only for Hurler syndrome, X-ALD and infantile Krabbe disease, are detailed studies available suggesting that HCT is indicated for carefully selected cases. Improvement of transplantation techniques and alternative therapies may change the recommended (contra-)indications for IEM. A recent example of emerging transplantation techniques is the fast availability of unrelated cord blood (UCB). UCB makes HCT feasible in patients with rapidly progressive neurological diseases. Because of the fast availability of UCB and therefore the ability to transplant shortly after diagnosis, there is no indication for patients in a moderate/good clinical condition to receive enzyme replacement therapy (ERT; in Hurler syndrome) prior to or during HCT and can ERT only be considered in patients with poor clinical condition. Mesenchymal stem cell infusions with HCT is an emerging technique, and might be interesting in halting the remaining defects after successful HCT. Improvement in HCT techniques and novel stem cell sources will significantly impact the safety and efficacy of this therapy as well as expand the list of candidate disorders. A good functioning worldwide registry would be necessary to measure the effects of the procedures performed in more detail.

Results of the Cord Blood Transplantation Study (COBLT): Outcomes of Unrelated Donor Umbilical Cord Blood Transplantation in Pediatric Patients with Lysosomal and Peroxisomal Storage Diseases

The Cord Blood Transplantation Study (COBLT), sponsored by the National Heart, Lung, and Blood Institute, is a phase II multicenter study designed to evaluate the use of cord blood in allogeneic transplantation. In this report, we evaluated the outcomes of cord blood transplantation in 69 patients with lysosomal and peroxisomal storage diseases. Patients with mucopolysaccharidoses I to III, mucolipidoses (ML) II (n = 36), adrenoleukodystrophy (n = 8), metachromatic leukodystrophy (n = 6), Krabbe disease (n = 16), and Tay-Sachs disease (n = 3) were enrolled between August 1999 and June 2004. All patients received the same preparative regimen, graft-versus-host disease (GVHD) prophylaxis, and supportive care. End points included survival, engraftment, GVHD, and toxicity. Sixty-nine patients (64% men; 81% white) with a median age of 1.8 years underwent transplantation with a median cell dose of 8.7 x 10(7)/kg. One-year survival was 72% (95% confidence interval, 61%-83%). The cumulative incidence of neutrophil engraftment by day 42 was 78% (95% confidence interval, 67%-87%) at a median of 25 days. Grade II to IV acute GVHD occurred in 36% of patients. Cord blood donors are readily available for rapid transplantation. Cord blood transplantation should be considered as frontline therapy for young patients with lysosomal and peroxisomal storage diseases.

Correction of metabolic, craniofacial, and neurologic abnormalities in MPS I mice treated at birth with adeno-associated virus vector transducing the human alpha-L-iduronidase gene

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.

Allogeneic stem cell transplantation for the treatment of lysosomal and peroxisomal metabolic diseases

This is a review of the clinical responses and prospectus of new therapies following use of allogeneic hematopoietic stem cell transplantation for the treatment of the following disorders: Hurlers syndrome (MPS 1-H), globoid cell leukodystrophy (GLD; Krabbes disease), adrenoleukodystrophy, metachromatic leukodystrophy, Wolmans disease, I-cell disease (mucolipidosis II; MLS-II), alpha-mannosidosis, fucosidosis, Niemann-Pick B/A disease, Slys disease (MPS VII), Gauchers disease (Gaucher-II-III), Battens disease, Farbers disease, Sanfilippo syndrome (MPS-III), Hunters disease (MPS-II), Maroteaux-Lamy syndrome (MPS-VI), and aspartylglucosaminuria (AGU). Over 500 patients with lysosomal and peroxisomal metabolic storage diseases due to deficiency of primary enzymes have been treated with hematopoietic stem cell transplantation since the initial patient was treated a quarter of century ago. Normal enzymatic activity has been robust and continuous over these years without the need for any medication. Proof of principle has been reported for multiple positive effects including that of the reconstruction of the central nervous system. Furthermore, the excellent engraftment rate along with significantly diminished graft-vs-host-disease needs to be emphasized. The genetic diseases enumerated above have remarkable differences from those discussed elsewhere in this issue of Seminars in Immunopathology. Each has a greater genetic heterogeneity. Misdiagnosis resulting in delay of treatment and further decline of function and ultimate quality of life occurs almost all the time. Neonatal screening of these diseases will be mandatory to vastly improve outcomes. Plans are being implemented to use dried blood spots on filter paper, as is commonly done for many other genetic diseases. Many new therapies are being adopted which should enhance positivity and acceptance of treatment by hematopoietic stem cell transplantation.

Cord-blood transplants from unrelated donors in patients with Hurler's syndrome

BACKGROUND

Hurler's syndrome (the most severe form of mucopolysaccharidosis type I) causes progressive deterioration of the central nervous system and death in childhood. Allogeneic bone marrow transplantation before the age of two years halts disease progression and prolongs life, but many children lack a bone marrow donor. We investigated the feasibility of using cord-blood transplants from unrelated donors and a myeloablative preparative regimen that did not involve total-body irradiation in young children with Hurler's syndrome.

METHODS

Between December 1995 and October 2002, 20 consecutive children with Hurler's syndrome received busulfan, cyclophosphamide, and antithymocyte globulin before receiving cord-blood transplants from unrelated donors. The children were subsequently evaluated for engraftment, adverse effects, and effects on disease symptoms.

RESULTS

Cord-blood donors had normal alpha-L-iduronidase activity (mean number of cells, 10.53x10(7) per kilogram of body weight) and were discordant for up to three of six HLA markers. Neutrophil engraftment occurred a median of 24 days after transplantation. Five patients had grade II or grade III acute graft-versus-host disease; none had extensive chronic graft-versus-host disease. Seventeen of the 20 children were alive a median of 905 days after transplantation, with complete donor chimerism and normal peripheral-blood alpha-L-iduronidase activity (event-free survival rate, 85 percent). Transplantation improved neurocognitive performance and decreased somatic features of Hurler's syndrome.

CONCLUSIONS

Cord blood from unrelated donors appears to be an excellent source of stem cells for transplantation in patients with Hurler's syndrome. Sustained engraftment can be achieved without total-body irradiation. Cord-blood transplantation favorably altered the natural history of Hurler's syndrome and thus may be important to consider in young children with this form of the disease.

Usefulness of bone marrow transplantation in the Hurler syndrome

The Hurler syndrome, an autosomal recessive storage disease of childhood, leads to death within the first decade of life from progressive deposition of glycosaminoglycans within the myointima of the coronary arteries and airways. Cardiac ultrasound findings of patients with this syndrome >10 years after successful bone marrow transplantation are described.

Hematopoietic cell transplantation for inherited metabolic diseases: an overview of outcomes and practice guidelines

For the past two decades, hematopoietic cell transplantation (HCT) has been used as effective therapy for selected inherited metabolic diseases (IMD) including Hurler (MPS IH) and Maroteaux-Lamy (MPS VI) syndromes, childhood-onset cerebral X-linked adrenoleukodystrophy (X-ALD), globoid-cell leukodystrophy (GLD), metachromatic leukodystrophy (MLD), alpha-mannosidosis, osteopetrosis, and others. Careful pre-HCT evaluation is critical and coordinated, multidisciplinary follow-up is essential in this field of transplantation. The primary goals of HCT for these disorders have been to promote long-term survival with donor-derived engraftment and to optimize the quality of life. Guidelines for HCT and monitoring are provided; a brief overview of long-term results is also presented.