Lentiviral-mediated correction of MPS VI cells and gene transfer to joint tissues

Mucopolysaccharidosis Type VI, an Updated Overview of the Disease

Mucopolysaccharidosis type VI, or Maroteaux-Lamy syndrome, is a rare, autosomal recessive genetic disease, mainly affecting the pediatric age group. The disease is due to pathogenic variants of the ARSB gene, coding for the lysosomal hydrolase N-acetylgalactosamine 4-sulfatase (arylsulfatase B, ASB). The enzyme deficit causes a pathological accumulation of the undegraded glycosaminoglycans dermatan-sulphate and chondroitin-sulphate, natural substrates of ASB activity. Intracellular and extracellular deposits progressively take to a pathological scenario, often severe, involving most organ-systems and generally starting from the osteoarticular apparatus. Neurocognitive and behavioral abilities, commonly described as maintained, have been actually investigated by few studies. The disease, first described in 1963, has a reported prevalence between 0.36 and 1.3 per 100,000 live births across the continents. With this paper, we wish to contribute an updated overview of the disease from the clinical, diagnostic, and therapeutic sides. The numerous in vitro and in vivo preclinical studies conducted in the last 10-15 years to dissect the disease pathogenesis, the efficacy of the available therapeutic treatment (enzyme replacement therapy), as well as new therapies under study are here described. This review also highlights the need to identify new disease biomarkers, potentially speeding up the diagnostic process and the monitoring of therapeutic efficacy.

Optimization of Meniscus Cell Transduction Using Lentivirus and Adeno-Associated Virus for Gene Editing and Tissue Engineering Applications

OBJECTIVES

The utilization of viral vectors to deliver genes of interest directly to meniscus cells and promote long-term modulation of gene expression may prove useful to enhance meniscus repair and regeneration. The objective of this study was to optimize and compare the potential of lentivirus (LV) and adeno-associated virus (AAV) to deliver transgenes to meniscus cells in both intact meniscus tissue and isolated primary cells in monolayer.

DESIGN

Porcine meniscus tissue explants and primary meniscus cells in monolayer were transduced with LV or self-complementary AAV2 (scAAV2) encoding green fluorescent protein (GFP). Following transduction, explants were enzymatically digested to isolate meniscus cells, and monolayer cells were trypsinized. Isolated cells were analyzed by flow cytometry to determine percent transduction.

RESULTS

LV and scAAV2 showed a high transduction efficiency in monolayer meniscus cells. scAAV2 was most effective at transducing cells within intact meniscus tissue but the efficiency was less than 20%. Outer zone meniscus cells were more readily transduced by both LV and scAAV2 than the inner zone cells. Higher virus titers and higher cell density resulted in improved transduction efficiency. Polybrene was necessary for the highest transduction efficiency with LV, but it reduced scAAV2 transduction.

CONCLUSIONS

Both LV and scAAV2 efficiently transduce primary meniscus cells but only scAAV2 can modestly transduce cells embedded in meniscus tissue. This work lays the foundation for viral gene transfer to be utilized to deliver bioactive transgenes or gene editing machinery, which can induce long-term and tunable expression of therapeutic proteins from tissue-engineered constructs for meniscus repair and regeneration.

Gene Delivery to Joints by Intra-Articular Injection

Most forms of arthritis are incurable, difficult to treat, and a major cause of disability in Western countries. Better local treatment of arthritis is impaired by the pharmacokinetics of the joint that make it very difficult to deliver drugs to joints at sustained, therapeutic concentrations. This is especially true of biologic drugs, such as proteins and RNA, many of which show great promise in preclinical studies. Gene transfer provides a strategy for overcoming this limitation. The basic concept is to deliver cDNAs encoding therapeutic products by direct intra-articular injection, leading to sustained, endogenous synthesis of the gene products within the joint. Proof of concept has been achieved for both in vivo and ex vivo gene delivery using a variety of vectors, genes, and cells in several different animal models. There have been a small number of clinical trials for rheumatoid arthritis (RA) and osteoarthritis (OA) using retrovirus vectors for ex vivo gene delivery and adeno-associated virus (AAV) for in vivo delivery. AAV is of particular interest because, unlike other viral vectors, it is able to penetrate deep within articular cartilage and transduce chondrocytes in situ. This property is of particular importance in OA, where changes in chondrocyte metabolism are thought to be fundamental to the pathophysiology of the disease. Authorities in Korea have recently approved the world's first arthritis gene therapy. This targets OA by the injection of allogeneic chondrocytes that have been transduced with a retrovirus carrying transforming growth factor-β₁ cDNA. Phase III studies are scheduled to start in the United States soon. Meanwhile, two additional Phase I trials are listed on Clinicaltrials.gov , both using AAV. One targets RA by transferring interferon-β, and the other targets OA by transferring interleukin-1 receptor antagonist. The field is thus gaining momentum and promises to improve the treatment of these common and debilitating diseases.

Reversal of established bone pathology in MPS VII mice following lentiviral-mediated gene therapy

Severe, progressive skeletal dysplasia is a major symptom of multiple mucopolysaccharidoses (MPS) types. While a gene therapy approach initiated at birth has been shown to prevent the development of bone pathology in different animal models of MPS, the capacity to correct developed bone disease is unknown. In this study, ex vivo micro-computed tomography was used to demonstrate that bone mass and architecture of murine MPS VII L5 vertebrae were within the normal range at 1month of age but by 2months of age were significantly different to normal. The difference between normal and MPS VII BV/TV increased with age reaching a maximal difference at approximately 4months of age. In mature MPS VII bone BV/TV is increased (51.5% versus 21.5% in normal mice) due to an increase in trabecular number (6.2permm versus 3.8permm in normal mice). The total number of osteoclasts in the metaphysis of MPS VII mice was decreased, as was the percentage of osteoclasts attached to bone. MPS VII osteoblasts produced significantly more osteoprotegerin (OPG) than normal osteoblasts and supported the production of fewer osteoclasts from spleen precursor cells than normal osteoblasts in a co-culture system. In contrast, the formation of osteoclasts from MPS VII spleen monocytes was similar to normal in vitro, when exogenous RANKL and m-CSF was added to the culture medium. Administration of murine β-glucuronidase to MPS VII mice at 4months of age, when bone disease was fully manifested, using lentiviral gene delivery resulted in a doubling of osteoclast numbers and a significant increase in attachment capacity (68% versus 29.4% in untreated MPS VII animals). Bone mineral volume rapidly decreased by 39% after gene therapy and fell within the normal range by 6months of age. Collectively, these results indicate that lentiviral-mediated gene therapy is effective in reversing established skeletal pathology in murine MPS VII.

Therapies of mucopolysaccharidosis IVA (Morquio A syndrome)

INTRODUCTION

Morquio A syndrome (mucopolysaccharidosis type IVA, MPS IVA) is one of the lysosomal storage diseases and is caused by the deficiency of N-acetylgalactosamine-6-sulfate sulfatase (GALNS). Deficiency of this enzyme leads to accumulation of glycosaminoglycans (GAGs), keratan sulfate (KS) and chondroitin-6-sulfate (C6S). The majority of KS is produced by chondrocytes, and therefore, the undegraded substrates accumulate mainly in cells and extracelluar matrix (ECM) of cartilage. This has a direct impact on cartilage and bone development, leading to systemic skeletal dysplasia. In patients with Morquio A, cartilage cells are vacuolated, and this results in abnormal chondrogenesis and/or endochondral ossification.

AREAS COVERED

This article describes the advanced therapies of Morquio A, focused on enzyme replacement therapy (ERT) and gene therapy to deliver the drug to avascular bone lesions. ERT and gene therapies for other types of MPS are also discussed, which provide therapeutic efficacy to bone lesions.

EXPERT OPINION

ERT, gene therapy and hematopietic stem therapy are clinically and/or experimentally conducted. However, there is no effective curative therapy for bone lesion to date. One of the limitations for Morquio A therapy is that targeting avascular cartilage tissues remains an unmet challenge. ERT or gene therapy with bone-targeting system will improve the bone pathology and skeletal manifestations more efficiently.

Optimization of scAAVIL-1ra In Vitro and In Vivo to Deliver High Levels of Therapeutic Protein for Treatment of Osteoarthritis

Osteoarthritis (OA) affects over 40 million people annually. We evaluated interleukin-1 receptor antagonist (IL-1ra) gene transfer in an equine model based on IL-1ra protein therapy which inhibits inflammation through blocking IL-1. Using the self-complementary adeno-associated virus (scAAV)IL-1ra equine gene as a starting construct, we optimized the transgene cassette by analyzing promoters (cytomegalovirus (CMV) versus chicken β-actin hybrid (CBh)), coding sequences (optimized versus unoptimized), vector capsid (serotype 2 versus chimeric capsid), and biological activity in vitro. AAV serotypes 2 and 2.5 CMV scAAVoptIL-1ra were tested in equine joints. We evaluated two doses of scAAVIL-1ra, scAAVGFP, and saline. We developed a novel endoscopy procedure and confirmed vector-derived transgene expression (GFP) in chondrocytes 6 months post-injection. AAVIL-1ra therapeutic protein levels were 200-800 ng/ml of synovial fluid over 23 and 186 days, respectively. No evidence of intra-articular toxicity was detected and no vector genomes were found in contralateral joints based on GFP fluorescence microscopy and quantitative PCR. Finally, we assayed vector-derived IL-1ra activity based on functional assays which supported anti-inflammatory activity of our protein. These studies represent the first large animal intra-articular gene transfer approach with a therapeutic gene using scAAV and demonstrate high levels of protein production over extended time supporting further clinical investigation using scAAV gene therapy for OA.Molecular Therapy - Nucleic Acids (2013) 2, e70; doi:10.1038/mtna.2012.61; published online 5 February 2013.

Gene therapy approaches for lysosomal storage disorders, a good model for the treatment of mendelian diseases

This review describes the different gene therapy technologies applied to approach lysosomal storage disorders, monogenic conditions, with known genetic and biochemical defects, for many of which animal models are available. Both viral and nonviral procedures are described, underlying the specific needs that the treatment of genetic disorders requires.

CONCLUSIONS

Lysosomal storage disorders represent a good model of study of gene therapeutic procedures that are, or could be, relevant to the treatment of several other mendelian diseases.

Rhodamine B and 2-acetamido-1,3,6-tri-O-acetyl-4-deoxy-4-fluoro-D-glucopyranose (F-GlcNAc) inhibit chondroitin/dermatan and keratan sulphate synthesis by different mechanisms in bovine chondrocytes

MPS disorders result from a deficiency or absence of glycosaminoglycan (GAG) degrading enzymes leading to an imbalance between the synthesis and degradation of GAGs and their subsequent accumulation in a range of cells. The inhibition of GAG synthesis using small chemical inhibitors has been proposed as a novel therapeutic approach to treatment. Several inhibitors have been shown to decrease heparan sulphate GAG synthesis and in this study we evaluated a novel fluorinated analog of N-acetylglucosamine (2-acetamido-1,3,6-tri-O-acetyl-4-deoxy-4-fluoro-D-glucopyranose (F-GlcNAc)) and rhodamine B for their ability to also inhibit the synthesis of chondroitin/dermatan and keratan sulphate GAGs present in bovine cartilage. Both inhibitors decreased GAG synthesis in chondrocyte monolayer culture and in cartilage chip explant culture in a dose dependent manner. Both inhibitors decreased the size of newly synthesised proteoglycans and in the case of F-GlcNAc this was due to a decrease in newly synthesised GAG chain size. Rhodamine B, however, did not affect GAG chain size, while both inhibitors decreased the amount of chondroitin/dermatan and keratan sulphate GAG equally. The expression of genes responsible for the initiation and elongation of chondroitin/dermatan sulphate and keratan sulphate GAGs were downregulated in the presence of rhodamine B but not in the presence of F-GlcNAc. Thus the 2 inhibitors appear to have differing effects on GAG synthesis, with F-GlcNAc inhibiting the epimerisation of UDP-GlcNAc to UDP-GalNAc thus decreasing the availability of monosaccharides for addition to the growing GAG chain, whereas rhodamine B is more likely to reduce the number of GAG chains. Together with previous data these 2 inhibitors are capable of non-specific inhibition of GAG synthesis, reducing the production of chondroitin/dermatan sulphate, keratan sulphate and heparan sulphate GAGs. As such they would be applicable to therapy in a range of MPS disorders.

Orthopedic gene therapy--lost in translation?

Orthopedic gene therapy has been the topic of considerable research for two decades. The preclinical data are impressive and many orthopedic conditions are well suited to genetic therapies. But there have been few clinical trials and no FDA-approved product exists. This paper examines why this is so. The reasons are multifactorial. Clinical translation is expensive and difficult to fund by traditional academic routes. Because gene therapy is viewed as unsafe and risky, it does not attract major funding from the pharmaceutical industry. Start-up companies are burdened by the complex intellectual property environment and difficulties in dealing with the technology transfer offices of major universities. Successful translation requires close interactions between scientists, clinicians and experts in regulatory and compliance issues. It is difficult to create such a favorable translational environment. Other promising fields of biological therapy have contemplated similar frustrations approximately 20 years after their founding, so there seem to be more general constraints on translation that are difficult to define. Gene therapy has noted some major clinical successes in recent years, and a sense of optimism is returning to the field. We hope that orthopedic applications will benefit collaterally from this upswing and move expeditiously into advanced clinical trials.

Glycosaminoglycan storage disorders: a review

Impaired degradation of glycosaminoglycans (GAGs) with consequent intralysosomal accumulation of undegraded products causes a group of lysosomal storage disorders known as mucopolysaccharidoses (MPSs). Characteristically, MPSs are recognized by increased excretion in urine of partially degraded GAGs which ultimately result in progressive cell, tissue, and organ dysfunction. There are eleven different enzymes involved in the stepwise degradation of GAGs. Deficiencies in each of those enzymes result in seven different MPSs, all sharing a series of clinical features, though in variable degrees. Usually MPS are characterized by a chronic and progressive course, with different degrees of severity. Typical symptoms include organomegaly, dysostosis multiplex, and coarse facies. Central nervous system, hearing, vision, and cardiovascular function may also be affected. Here, we provide an overview of the molecular basis, enzymatic defects, clinical manifestations, and diagnosis of each MPS, focusing also on the available animal models and describing potential perspectives of therapy for each one.

Getting arthritis gene therapy into the clinic

Gene transfer technologies enable the controlled, targeted and sustained expression of gene products at precise anatomical locations, such as the joint. In this way, they offer the potential for more-effective, less-expensive treatments of joint diseases with fewer extra-articular adverse effects. A large body of preclinical data confirms the utility of intra-articular gene therapy in animal models of rheumatoid arthritis and osteoarthritis. However, relatively few clinical trials have been conducted, only one of which has completed phase II. This article summarizes the status in 2010 of the clinical development of gene therapy for arthritis, identifies certain constraints to progress and suggests possible solutions.

Impact of biological agents and tissue engineering approaches on the treatment of rheumatic diseases

The treatment of rheumatic diseases has been the focus of many clinical studies aiming to achieve the best combination of drugs for symptom reduction. Although improved understanding of the pathophysiology of rheumatic diseases has led to the identification of effective therapeutic strategies, its cure remains unknown. Biological agents are a breakthrough in the treatment of these diseases. They proved to be more effective than the other conventional therapies in refractory inflammatory rheumatic diseases. Among them, tumor necrosis factor inhibitors are widely used, namely Etanercept, Infliximab, or Adalimumab, alone or in combination with disease-modifying antirheumatic drugs. Nevertheless, severe adverse effects have been detected in patients with history of recurrent infections, including cardiac failure or malignancy. Currently, most of the available therapies for rheumatic diseases do not have sufficient tissue specificity. Consequently, high drug doses must be administrated systemically, leading to adverse side effects associated with its possible toxicity. Drug delivery systems, by its targeted nature, are excellent solutions to overcome this problem. In this review, we will describe the state-of-the-art in clinical studies on the treatment of rheumatic diseases, emphasizing the use of biological agents and target drug delivery systems. Some alternative novel strategies of regenerative medicine and its implications for rheumatic diseases will also be discussed.

Orthopedic gene therapy in 2008

Orthopedic disorders, although rarely fatal, are the leading cause of morbidity and impose a huge socioeconomic burden. Their prevalence will increase dramatically as populations age and gain weight. Many orthopedic conditions are difficult to treat by conventional means; however, they are good candidates for gene therapy. Clinical trials have already been initiated for arthritis and the aseptic loosening of prosthetic joints, and the development of bone-healing applications is at an advanced, preclinical stage. Other potential uses include the treatment of Mendelian diseases and orthopedic tumors, as well as the repair and regeneration of cartilage, ligaments, and tendons. Many of these goals should be achievable with existing technologies. The main barriers to clinical application are funding and regulatory issues, which in turn reflect major safety concerns and the opinion, in some quarters, that gene therapy should not be applied to nonlethal, nongenetic diseases. For some indications, advances in nongenetic treatments have also diminished enthusiasm. Nevertheless, the preclinical and early clinical data are impressive and provide considerable optimism that gene therapy will provide straightforward, effective solutions to the clinical management of several common debilitating disorders that are otherwise difficult and expensive to treat.