Synthesis of Lipophilic Core-Shell Fe3O4@SiO2@Au Nanoparticles and Polymeric Entrapment into Nanomicelles: A Novel Nanosystem for in Vivo Active Targeting and Magnetic Resonance-Photoacoustic Dual Imaging.

In this work, iron/silica/gold core-shell nanoparticles (Fe3O4@SiO2@Au NPs) characterized by magnetic and optical properties have been synthesized to obtain a promising theranostic platform. To improve their biocompatibility, the obtained multilayer nanoparticles have been entrapped in polymeric micelles, decorated with folic acid moieties, and tested in vivo for photoacoustic and magnetic resonance imaging detection of ovarian cancer.

A semi-nested real-time PCR method to detect low chimerism percentage in small quantity of hematopoietic stem cell transplant DNA samples.

Chimerism status evaluation of post-allogeneic hematopoietic stem cell transplantation samples is essential to predict post-transplant relapse. The most commonly used technique capable of detecting small increments of chimerism is quantitative real-time PCR. Although this method is already used in several laboratories, previously described protocols often lack sensitivity and the amount of the DNA required for each chimerism analysis is too high. In the present study, we compared a novel semi-nested allele-specific real-time PCR (sNAS-qPCR) protocol with our in-house standard allele-specific real-time PCR (gAS-qPCR) protocol. We selected two genetic markers and analyzed technical parameters (slope, y-intercept, R2, and standard deviation) useful to determine the performances of the two protocols. The sNAS-qPCR protocol showed better sensitivity and precision. Moreover, the sNAS-qPCR protocol requires, as input, only 10 ng of DNA, which is at least 10-fold less than the gAS-qPCR protocols described in the literature. Finally, the proposed sNAS-qPCR protocol could prove very useful for performing chimerism analysis with a small amount of DNA, as in the case of blood cell subsets.

Use of Polylactide-Co-Glycolide-Nanoparticles for Lysosomal Delivery of a Therapeutic Enzyme in Glycogenosis Type II Fibroblasts.

Glycogenosis type II, or Pompe Disease, is a lysosomal storage disease caused by the deficiency of acid alpha-glucosidase (GAA), leading to glycogen accumulation in muscles. A recombinant human GAA (rhGAA, Myozyme®) is currently used for enzyme replacement therapy. Despite its efficacy in most of patients, some of them show a diminished response to the treatment with rapidly progressive clinical deterioration, due to immuno-mediated enzyme inactivation. To demonstrate that Nanoparticles (NPs) could be profitably exploited to carry macromolecules, PLGA NPs loaded with rhGAA (GAA-NPs) were prepared by double emulsion solvent evaporation. Their surface morphology, particle size, zeta-potential and biochemical activity were assessed. "Pulse and chase" experiments were made by administrating GAA-NPs on patients' fibroblasts. Biochemical activity tests showed a more efficient cellular uptake of rhGAA loaded to NPs and a more significant stability of the enzyme (up to 7 days) in vitro, if compared to the same amount of rhGAA free enzyme. This data allows to envision in vivo experiments, in significant animal models, to further characterize lysosomal enzyme loaded-NPs' efficacy and toxicity.

Impact of DCM-Causing Genetic Background on Long-Term Response to Cardiac Resynchronization Therapy.

BACKGROUND: Patients with nonischemic dilated cardiomyopathy (DCM), severe left ventricular (LV) dysfunction, and complete left bundle branch block benefit from cardiac resynchronization therapy (CRT). However, a large heterogeneity of response to CRT is described. Several predictors of response to CRT have been identified, but the role of the underlying genetic background is still poorly explored. OBJECTIVES: In the present study, the authors sought to define differences in LV remodeling and outcome prediction after CRT when stratifying patients according to the presence or absence of DCM-causing genetic background. METHODS: From our center, 74 patients with DCM subjected to CRT and available genetic testing were retrospectively enrolled. Carriers of causative monogenic variants in validated DCM-causing genes, and/or with documented family history of DCM, were classified as affected by genetically determined disease (GEN+DCM) (n = 25). Alternatively, by idiopathic dilated cardiomyopathy (idDCM) (n = 49). The primary outcome was long-term LV remodeling and prevalence of super response to CRT (evaluated at 24-48 months after CRT); the secondary outcome was heart failure-related death/heart transplant/LV assist device. RESULTS: GEN+DCM and idDCM patients were homogeneous at baseline with the exception of QRS duration, longer in idDCM. The median follow-up was 55 months. Long-term LV reverse remodeling and the prevalence of super response were significantly higher in the idDCM group (27% in idDCM vs 5% in GEN+DCM; P = 0.025). The heart failure-related death/heart transplant/LV assist device outcome occurred more frequently in patients with GEN+DCM (53% vs 24% in idDCM; P = 0.028). CONCLUSIONS: Genotyping contributes to the risk stratification of patients with DCM undergoing CRT implantation in terms of LV remodeling and outcomes.

Inborn Errors of Immunity in Children with Autoimmune and Allergic Complaints: A Single Center Experience from Diagnosis to Treatment.

Inborn errors of immunity (IEI) associated with immune dysregulation are not sufficiently addressed in shared recommendation, resulting in delayed diagnosis and high morbidity. The availability of precision medicine for some of these immune defects makes it urgent to evaluate effective strategies to diagnose and treat such defects before the occurrence of severe complications. A diagnosis of an IEI in these patients enabled the use of a more specific treatment in most cases, and these have the potential to prevent further disease progression. We studied immune dysregulation diseases in 30 patients with autoimmune or allergic phenotypes, exploiting data from clinics and immunophenotype, genetic and transcriptome investigations, and 6 of them were diagnosed with a monogenic disorder. Our results confirm that a non-negligible number of children with IEIs may present with signs and symptoms of immune dysregulation and share many features with common multifactorial immune conditions. Reaching a genetic diagnosis becomes more likely in the presence of multiple clinical manifestations, especially when in association with abnormalities of lymphocytes subsets and/or immunoglobulins levels. Moreover, 5 of 6 patients that obtained a diagnosis of monogenic disorder received precision therapy, in four cases with a good or moderate response.

Erythropoietic protoporphyria: case reports for clinical and therapeutic hints.

BACKGROUND: Erythropoietic protoporphyria is a rare disorder which represents an important health problem in children, causing painful photosensitivity. Little is known on the correlation between genetic profile and clinical manifestations. The standard of care for Erythropoietic protoporphyria is based on avoiding sun and using sun protections, but recent literature has suggested that cimetidine may have a role in improving sun sensitivity. Herein we report our case series describing the successful use of cimetidine and analyzing potential phenotype-genotype correlations. CASE PRESENTATION: This case series describes five patients presented to our Rheumatology Service complaining sun sensitivity. Blood exams and genetic analysis were consistent with the diagnosis of erythropoietic protoporphyria. Four of 5 patients received cimetidine in addition to standard therapies and the effect of treatment was evaluated by Erythropoietic Protoporphyria - Quality of Life questionnaire. CONCLUSIONS: Erythropoietic protoporphyria usually manifests in early childhood after a short sun exposure. Skin manifestations are the main reason for investigations, although sometimes they can be more subtle, leading to a significant diagnostic delay. Skin diseases in children can have profound effects on their family and social relationships. A treatment with cimetidine appears to be an excellent therapeutic option in children with Erythropoietic protoporphyria.

Β-hexosaminidase over-expression affects lysosomal glycohydrolases expression and glycosphingolipid metabolism in mammalian cells.

Lysosomes are not only degrading organelles but also involved in other critical cellular processes. In addition, active lysosomal glycohydrolases have been detected in an extra-lysosomal compartment: the presence of glycohydrolases on the plasma membrane (PM) has been widely demonstrated, and a possible role on the modification of the cell surface glycosphingolipids (GSL) participating in the modulation of cell functions such as cell-to-cell interactions and signal transduction pathways has been proposed. On this basis, the coordinated expression of lysosomal glycohydrolases and their translocation to the PM appear to be crucial for many cellular events. In this paper, we report evidence for the existence of a coordinated mechanism regulating the expression/activity of both lysosomal and PM-associated glycohydrolases. We show that the over-expression of the acidic glycohydrolase ß-hexosaminidase α-subunit in mouse NIH/3T3 fibroblasts induces the increased expression of the Hex ß-subunit necessary to form the active isoenzyme dimers as well as of other glycohydrolases participating in the GSL catabolism, such as ß-galactosidase and ß-glucocerebrosidase. More interestingly, this regulatory effect was also extended to the PM-associated hydrolases. In addition, transfected cells displayed a rearrangement of the GSL expression pattern that cannot be simply explained by the increased activity of a single enzyme. These observations clearly indicate that the expression level of metabolically related glycohydrolases is regulated in a coordinated manner and this regulation mechanism also involves the PM-associated isoforms.

Prognostic Prediction of Genotype vs Phenotype in Genetic Cardiomyopathies.

BACKGROUND: Diverse genetic backgrounds often lead to phenotypic heterogeneity in cardiomyopathies (CMPs). Previous genotype-phenotype studies have primarily focused on the analysis of a single phenotype, and the diagnostic and prognostic features of the CMP genotype across different phenotypic expressions remain poorly understood. OBJECTIVES: We sought to define differences in outcome prediction when stratifying patients based on phenotype at presentation compared with genotype in a large cohort of patients with CMPs and positive genetic testing. METHODS: Dilated cardiomyopathy (DCM), arrhythmogenic right ventricular cardiomyopathy, left-dominant arrhythmogenic cardiomyopathy, and biventricular arrhythmogenic cardiomyopathy were examined in this study. A total of 281 patients (80% DCM) with pathogenic or likely pathogenic variants were included. The primary and secondary outcomes were: 1) all-cause mortality (D)/heart transplant (HT); 2) sudden cardiac death/major ventricular arrhythmias (SCD/MVA); and 3) heart failure-related death (DHF)/HT/left ventricular assist device implantation (LVAD). RESULTS: Survival analysis revealed that SCD/MVA events occurred more frequently in patients without a DCM phenotype and in carriers of DSP, PKP2, LMNA, and FLNC variants. However, after adjustment for age and sex, genotype-based classification, but not phenotype-based classification, was predictive of SCD/MVA. LMNA showed the worst trends in terms of D/HT and DHF/HT/LVAD. CONCLUSIONS: Genotypes were associated with significant phenotypic heterogeneity in genetic cardiomyopathies. Nevertheless, in our study, genotypic-based classification showed higher precision in predicting the outcome of patients with CMP than phenotype-based classification. These findings add to our current understanding of inherited CMPs and contribute to the risk stratification of patients with positive genetic testing.

Immunity and Genetics at the Revolving Doors of Diagnostics in Primary Immunodeficiencies.

Primary immunodeficiencies (PIDs) are a large and growing group of disorders commonly associated with recurrent infections. However, nowadays, we know that PIDs often carry with them consequences related to organ or hematologic autoimmunity, autoinflammation, and lymphoproliferation in addition to simple susceptibility to pathogens. Alongside this conceptual development, there has been technical advancement, given by the new but already established diagnostic possibilities offered by new genetic testing (e.g., next-generation sequencing). Nevertheless, there is also the need to understand the large number of gene variants detected with these powerful methods. That means advancing beyond genetic results and resorting to the clinical phenotype and to immunological or alternative molecular tests that allow us to prove the causative role of a genetic variant of uncertain significance and/or better define the underlying pathophysiological mechanism. Furthermore, because of the rapid availability of results, laboratory immunoassays are still critical to diagnosing many PIDs, even in screening settings. Fundamental is the integration between different specialties and the development of multidisciplinary and flexible diagnostic workflows. This paper aims to tell these evolving aspects of immunodeficiencies, which are summarized in five key messages, through introducing and exemplifying five clinical cases, focusing on diseases that could benefit targeted therapy.

Genetic and immunologic findings in children with recurrent aphthous stomatitis with systemic inflammation.

BACKGROUND: Recurrent aphthous stomatitis with systemic signs of inflammation can be encountered in inflammatory bowel disease, Behçet's disease (BD), Systemic Lupus Erythematosus (SLE). In addition, it has been proposed that cases with very early onset in childhood can be underpinned by rare monogenic defects of immunity, which may require targeted treatments. Thus, subjects with early onset recurrent aphthous stomatitis receiving a clinical diagnosis of BD-like or SLE-like disease may deserve a further diagnostic workout, including immunologic and genetic investigations. OBJECTIVE: To investigate how an immunologic, genetic and transcriptomics assessment of interferon inflammation may improve diagnosis and care in children with recurrent aphthous stomatitis with systemic inflammation. METHODS: Subjects referred to the pediatric rheumatologist for recurrent aphthous stomatitis associated with signs of systemic inflammation from January 2015 to January 2020 were enrolled in the study and underwent analysis of peripheral lymphocyte subsets, sequencing of a 17-genes panel and measure of interferon score. RESULTS: We enrolled 15 subjects (12 females, median age at disease onset 4 years). The clinical diagnosis was BD in 8, incomplete BD in 5, BD/SLE overlap in 1, SLE in 1. Pathogenic genetic variants were detected in 3 patients, respectively 2 STAT1 gain of function variants in two patients classified as BD/SLE overlap and SLE, and 1 TNFAIP3 mutation (A20 haploinsufficiency) in patients with BD. Moreover 2 likely pathogenic variants were identified in DNASE1L3 and PTPN22, both in patients with incomplete BD. Interferon score was high in the two patients with STAT1 GOF mutations, in the patient with TNFAIP3 mutation, and in 3 genetic-negative subjects. In two patients, the treatment was modified based on genetic results. CONCLUSIONS: Although recurrent aphthous stomatitis associated with systemic inflammation may lead to a clinical diagnosis of BD or SLE, subjects with early disease onset in childhood deserve genetic investigation for rare monogenic disorders. A wider genetic panel may help disclosing the genetic background in the subset of children with increased interferon score, who tested negative in this study.

Nanotechnology-Based Cisplatin Intracellular Delivery to Enhance Chemo-Sensitivity of Ovarian Cancer.

BACKGROUND: Platinum resistance is a major challenge in the management of ovarian cancer. Even low levels of acquired resistance at the cellular level lead to impaired response to cisplatin. In ovarian cancer intraperitoneal therapy, nanoparticle formulation can improve the cisplatin's pharmacokinetics and safety profile. PURPOSE: This work aimed to investigate the chemo-sensitivity of ovarian cancer SKOV3 cells upon short-term (72h) single treatment of cisplatin and cisplatin-loaded biodegradable nanoparticles (Cis-NP). The aim was then to determine the therapeutic properties of Cis-NP in vivo using a SKOV3-luc cells' xenograft model in mice. METHODS: Cell cytotoxicity was assessed after the exposure of the cell culture to cisplatin or Cis-NP. The effect of treatments on EMT and CSC-like phenotype was studied by analyzing a panel of markers by flow cytometry. Intracellular platinum concentration was determined by inductively coupled plasma mass spectrometry (ICS-MS), and gene expression was evaluated by RNAseq analysis. The efficacy of intraperitoneal chemotherapy was evaluated in a SKOV3-luc cells' xenograft model in mice, through a combination of bioluminescence imaging, histological, and immunohistochemical analyses. RESULTS: We observed in vitro that short-term treatment of cisplatin has a critical role in determining the potential induction of chemoresistance, and a nanotechnology-based drug delivery system can modulate it. The RNAseq analysis underlines a protective effect of nanoparticle system according to their ability to down-regulate several genes involved in chemoresistance, cell proliferation, and apoptosis. The highest intracellular platinum concentration obtained with Cis-NP treatment significantly improved the efficacy. Consistent with in vitro results, we found that Cis-NP treatment in vivo can significantly reduce tumor burden and aggressiveness compared to the free drug. CONCLUSION: Nanoparticle-mediated cisplatin delivery may serve as an intracellular depot impacting the cisplatin pharmacodynamic performance at cellular levels. These features may contribute to improving the drawbacks of conventional intraperitoneal therapy, and therefore will require further investigations in vivo.

[Diagnostic work-up and clinical management of cardiomyopathies: the operative protocol from the Cardiothoracovascular Department of Trieste, Italy]. / Inquadramento e gestione delle cardiomiopatie: il protocollo della Cardiologia di Trieste.

Cardiomyopathies are primary myocardial disorders, genetically determined, with clinical onset between the third and the fifth decade of life. They represent the main causes of sudden cardiac death and heart failure in the youth. The more common myocardial diseases in clinical practice are dilated cardiomyopathy, arrhythmogenic cardiomyopathy and hypertrophic cardiomyopathy. Next generation sequencing techniques, recently available for genetics researches, together with the diffusion of advanced imaging techniques, permitted in the last years a deeper knowledge of these pathologies. Nevertheless, diagnosis, etiology and several aspects of patients' clinical management remain complex and controversial. This review paper aims to propose some operative flow-charts, derived from scientific evidences and the internal protocol of the Cardiothoracovascular Department of Trieste Hospital, Italian referral Center for cardiomyopathies and heart failure, with more than 30 years of experience in diagnosis and management of patients who suffer from primary myocardial disorders.

In vitro treatment of congenital disorder of glycosylation type Ia using PLGA nanoparticles loaded with GDP­Man.

Congenital disorder of glycosylation (CDG) type Ia is a multisystem disorder that occurs due to mutations in the phosphomannomutase 2 (PMM2) gene, which encodes for an enzyme involved in the N­glycosylation pathway. Mutated PMM2 leads to the reduced conversion of mannose­6­P to mannose­1­P, which results in low concentration levels of guanosine 5'­diphospho­D­mannose (GDP­Man), a nucleotide­activated sugar essential for the construction of protein oligosaccharide chains. In the present study, an in vitro therapeutic approach was used, based on GDP­Man­loaded poly (D,L­lactide­co­glycolide) (PLGA) nanoparticles (NPs), which were used to treat CDG­Ia fibroblast cultures, thus bypassing the glycosylation pathway reaction catalysed by PMM2. To assess the degree of hypoglycosylation in vitro, the present study examined the activities of α­mannosidase, ß­glucoronidase and ß­galactosidase in defective and normal fibroblasts. GDP­Man (30 µg/ml GDP­Man PLGA NPs) was incubated for 48 h with the cells and the specific activities of α­mannosidase and ß­galactosidase were estimated at 69 and 92% compared with healthy controls. The residual activity of ß­glucoronidase increased from 6.5 to 32.5% and was significantly higher compared with that noted in the untreated CDG­Ia fibroblasts. The glycosylation process of fibroblasts was also analysed by two­dimensional electrophoresis. The results demonstrated that treatment caused the reappearance of several glycosylated proteins. The data in vitro showed that GDP­Man PLGA NPs have desirable efficacy and warrant further evaluation in a preclinical validation animal model.

Could a chimeric condition be responsible for unexpected genetic syndromes? The role of the single nucleotide polymorphism-array analysis.

In this paper, is reported the identification of two chimeric patients, a rare finding if sexual abnormalities are absent. However, their chimeric condition is responsible at least for the Silver-Russell phenotype observed in one of the two patients. By single nucleotide polymorphism-array analyses, it was possible to clearly define the mechanism responsible for this unusual finding, underlining the importance of this technique in bringing out the perhaps submerged world of chimeras.

Imaging and therapy of ovarian cancer: clinical application of nanoparticles and future perspectives.

Despite significant advances in cancer diagnostics and treatment, ovarian cancers (OC) continue to kill more than 150,000 women every year worldwide. Due to the relatively asymptomatic nature and the advanced stage of the disease at the time of diagnosis, OC is the most lethal gynecologic malignancy. The current treatment for advanced OC relies on the synergistic effect of combining surgical cytoreduction and chemotherapy; however, beside the fact that chemotherapy resistance is a major challenge in OC management, new imaging strategies are needed to target microscopic lesions and improve both cytoreductive surgery and patient outcomes. In this context, nanostructured probes are emerging as a new class of medical tool that can simultaneously provide imaging contrast, target tumor cells, and carry a wide range of medicines resulting in better diagnosis and therapeutic precision. Herein we summarize several exemplary efforts in nanomedicine for addressing unmet clinical needs.

Neither hereditary periodic fever nor periodic fever, aphthae, pharingitis, adenitis: Undifferentiated periodic fever in a tertiary pediatric center.

AIM: To describe the frequency and clinical characteristics of patients with undifferentiated periodic fever (UPF) and to investigate whether a clinical classification of UPF based on the PRINTO-Eurofever score can help predicting the response to treatment and the outcome at follow-up. METHODS: Clinical and therapeutic information of patients with recurrent fever who presented at a single pediatric rheumatology center from January 2006 through April 2016 were retrospectively collected. Patients with a clinical suspicion of hereditary periodic fever (HPF) syndrome and patients with clinical picture of periodic fever, aphthae, pharingitis, adenitis (PFAPA) who were refractory to tonsillectomy underwent molecular analysis of five HPF-related genes: MEFV (NM_000243.2), MVK (NM_000431.3), TNFRSF1A (NM_001065.3), NLRP3 (NM_001079821.2), NLRP12 (NM_001277126.1). All patients who had a negative genetic result were defined as UPF and further investigated. PRINTO-Eurofever score for clinical diagnosis of HPF was calculated in all cases. RESULTS: Of the 221 patients evaluated for periodic fever, twelve subjects with a clinical picture of PFAPA who were refractory to tonsillectomy and 22 subjects with a clinical suspicion of HPF underwent genetic analysis. Twenty-three patients (10.4%) resulted negative and were classified as UPF. The median age at presentation of patients with UPF was 9.5 mo (IQR 4-24). Patients with UPF had a higher frequency of aphthae (52.2% vs 0%, P = 0.0026) and musculoskeletal pain (65.2% vs 18.2%, P = 0.0255) than patients with genetic confirmed HPF. Also, patients with UPF had a higher frequency of aphthous stomatitis (52.2% vs 10.7%, P < 0.0001), musculoskeletal pain (65.2% vs 8,0%, P < 0.0001), and abdominal pain (52.2% vs 4.8%, P < 0.0001) and a lower frequency of pharyngitis (56.6% vs 81.3%, P = 0.0127) compared with typical PFAPA in the same cohort. Twenty-one of 23 patients with UPF (91.3%) received steroids, being effective in 16; 13 (56.2%) were given colchicine, which was effective in 6. Symptoms resolution occurred in 2 patients with UPF at last follow-up. Classification according to the PRINTO-Eurofever score did not correlate with treatment response and prognosis. CONCLUSION: UPF is not a rare diagnosis among patients with periodic fever. Clinical presentation place UPF half way on a clinical spectrum between PFAPA and HPF. The PRINTO-Eurofever score is not useful to predict clinical outcome and treatment response in these patients.

Carbohydrate-deficient transferrin (CDT) as a biochemical tool for the screening of congenital disorders of glycosylation (CDGs).

OBJECTIVE: The aim of this study was to provide a tool based on CDT measurements for a diagnostic approach to identify patients affected by congenital disorders of glycosylation (CDG) in a selected population. DESIGN AND METHODS: Serum carbohydrate-deficient transferrin (CDT) of pediatric and adult patients (a total of 168 individuals) with neurological symptoms was analyzed. Abnormal results were confirmed by HPLC analysis and by enzymatic and molecular studies. RESULTS: We found 6 patients (3.8%) with abnormal serum CDT; only two of them (1.9%) showed increased amounts of disialo and asialo with HPLC analysis and were classified as CDG-Ia, the most frequent form of CDG, due to a deficiency of the phosphomannomutase enzyme. CONCLUSIONS: The CDT quantitative immunoturbidimetric procedure is a useful tool for CDG screening. HPLC analysis, however, permitted the correct identification of asialo and disialo transferrin concentrations.

A technical application of quantitative next generation sequencing for chimerism evaluation.

At present, the most common genetic diagnostic method for chimerism evaluation following hematopoietic stem cell transplantation is microsatellite analysis by capillary electrophoresis. The main objective was to establish, through repeated analysis over time, if a complete chimerism was present, or if the mixed chimerism was stable, increasing or decreasing over time. Considering the recent introduction of next generation sequencing (NGS) in clinical diagnostics, a detailed study evaluating an NGS protocol was conducted, coupled with a custom bioinformatics pipeline, for chimerism quantification. Based on the technology of Ion AmpliSeq, a 44­amplicon custom chimerism panel was designed, and a custom bioinformatics pipeline dedicated to the genotyping and quantification of NGS data was coded. The custom chimerism panel allowed identification of an average of 16 informative recipient alleles. The limit of detection of the protocol was fixed at 1% due to the NGS background (<1%). The protocol followed the standard Ion AmpliSeq library preparation and Ion Torrent Personal Genome Machine guidelines. Overall, the present study added to the scientific literature, identifying novel technical details for a possible future application of NGS for chimerism quantification.

Expression and purification of a human, soluble Arylsulfatase A for Metachromatic Leukodystrophy enzyme replacement therapy.

The production of active Arylsulfatase A is a key step in the development of enzyme replacement therapy for Metachromatic Leukodystrophy. To obtain large amounts of purified Arylsulfatase A for therapeutic use, we combined a retroviral expression system with a versatile and rapid purification protocol that can easily and reliably be adapted to high-throughput applications. The purification method consists of an initial ion-exchange DEAE-cellulose chromatography step followed by immuno-affinity purification using a polyclonal antibody against a 29-mer peptide of the Arylsulfatase A sequence. Immuno-adsorbed protein was eluted with a combination of acidic pH and an optimal concentration of the 29-mer peptide. This protocol reproducibly yielded approximately 100 microg of >99% pure human Arylsulfatase A, corresponding to 152 mU of enzyme activity, per liter of culture medium with properties similar to those of human non-recombinant protein.