Alerta monitoramento do horizonte tecnológico: Etranacogene dezaparvovec para o tratamento de Hemofilia B / Alert monitoring of the technological horizon: Etranacogene dezaparvovec for the treatment of Hemophilia B

A TECNOLOGIA: Condição clínica: A hemofilia é um distúrbio hereditário da hemostasia causado por uma deficiência do fator VIII de coagulação (na hemofilia A) ou fator IX (na hemofilia B) como resultado de defeitos nos genes F8 e F9, respectivamente. Esta condição está associada ao sangramento prolongado e excessivo. Aproximadamente 70% dos casos surgem por herança recessiva ligada ao cromossomo X (por isso as manifestações clínicas são predominantes em indivíduos do sexo masculino), enquanto os outros 30% ocorrem sem história familiar conhecida (casos esporádicos). Segundo dados da Federação Mundial de Hemofilia (FMH), a hemofilia afeta cerca de 1.125.000 indivíduos mundialmente, dos quais 37,15% apresentam formas graves da doença. No que se refere ao Brasil, de acordo o relatório de 2021 da FMH, a população com hemofilia é de 13.337 indivíduos, ocupando a terceira posição global ­ atrás somente da Índia e dos Estados Unidos. Em relação à hemofilia B, estima-se uma prevalência média de 3,8 casos para 100.000 homens, sendo de 1,1/100.000 especificamente para casos graves. Quanto à prevalência ao nascer, são estimados cinco casos de hemofilia B por 100.000 nascimentos masculinos, sendo 1,5/100.000 correspondentes à forma grave. DESCRIÇÃO DA TECNOLOGIA: O etranacogene dezaparvovec (CSL-22, AMT-060, AMT-061, EtranaDez) é uma terapia gênica baseada em vírus adenoassociado tipo 5 (AAV5) transportando a variante Pádua do transgene Fator IX por meio da tecnologia de vetor NAV da RegenX Biosciences, para o tratamento potencial de hemofilia B grave e moderada em adultos que não apresentam inibidores do fator IX. O etranacogene dezaparvovec é produzido pela CSL Behring LLC e está disponível para comercialização nos Estados Unidos. Não há até então registro sanitário para comercialização no Brasil. INFORMAÇÕES REGULATÓRIAS: Informações sobre registro: O etranacogene dezaparvovec (Hemgenix ®) foi desenvolvido pela empresa CSL Behring LLC e aprovado pelo US Food and Drug Administration, nos Estados Unidos, em 22 novembro de 2022, com indicação inicial para o tratamento de adultos com hemofilia B (deficiência congênita do fator IX) que atualmente usam terapia profilática de fator IX, ou com histórico ou hemorragia grave atual com risco de morte, ou que apresentam episódios de sangramento espontâneos repetidos e graves. PANORAMA DE DESENVOLVIMENTO: Estratégia de busca: A busca por evidências foi composta por duas etapas. A primeira etapa objetivou identificar ensaios clínicos acerca do uso etranacogene dezaparvovec para tratamento da hemofilia B. As seguintes bases foram consultadas, em 21 de dezembro de 2022: ClinicalTrials.gov, International Clinical Trials Registry Platform, German Clinical Trials Register, European Union Clinical Trials Register, Australian New Zealand Clinical Trials Registry, Chinese Clinical Trial Registry e Registro Brasileiro de Ensaios Clínicos, conforme detalhado no Apêndice 2. Adicionalmente, a base Cortellis foi consultada em 01 de dezembro de 2022, pesquisando-se pelo termo "etranacogene dezaparvovec. A segunda etapa consistiu em buscas nas bases de dados gerais Medline via PubMed, Embase e Lilacs. As estratégias de buscas estruturadas (Apêndice 3) foram elaboradas utilizando vocabulário controlado, seus sinônimos e termos livres, de acordo com cada base de dados, a partir dos termos relacionados ao medicamento (etranacogene dezaparvovec) e à doença (hemofilia B). Além disso, foram realizadas buscas manuais nos repositórios de preprint medRxiv e Authorea e no Google Acadêmico. As buscas foram realizadas em 21 de dezembro de 2022. Não houve restrição quanto ao idioma. Os critérios de elegibilidade estabelecidos para a busca por evidências de estudos publicados ou não publicados foram: ensaios clínicos randomizados ou não, a partir da fase 2, em que o etranacogene dezaparvovec tenha sido utilizado para o tratamento da hemofilia B, em qualquer fase em andamento ou finalizados em até cinco anos. A seleção da evidência foi realizada por um revisor e verificada por um segundo. A evidência identificada nas etapas anteriores foi importada para o software EndNote®, para remoção das duplicatas e posteriormente para o Rayyan®, para a realização da seleção da evidência. Primeiramente, foi realizada a leitura de títulos e resumos e os estudos foram excluídos com base nos critérios estabelecidos. Após essa etapa, foi realizada a leitura dos textos completos para verificação da elegibilidade dos estudos. CONSIDERAÇÕES FINAIS: Diferentes alternativas terapêuticas, incluindo terapias gênicas, vêm sendo estudadas como potenciais tratamentos para o tratamento da hemofilia B. Dentre as terapias gênicas, está o etranacogene dezaparvovec, uma tecnologia baseada em vírus AAV5 projetada para entregar uma cópia de um gene que codifica a variante Pádua do Fator IX de coagulação humana. A infusão intravenosa única dessa terapia resulta em transdução celular e aumento na atividade do fator IX circulante em pacientes com hemofilia B. O maior potencial da terapia gênica é fornecer estabilidade de longo prazo da expressão da atividade do fator de coagulação endógeno com um tratamento de dose única. Ao todo, existem três ensaios clínicos (fase 1/2, fase 2b e fase 3) em andamento ou concluídos com o objetivo de avaliar a eficácia e segurança do etranacogene dezaparvovec no tratamento de pacientes adultos do sexo masculino com hemofilia B grave ou moderada. Esses ensaios clínicos multicêntricos não são randomizados nem cegos, as amostras são pequenas e têm seguimentos relativamente curtos. Todos os estudos foram financiados pela empresa produtora da tecnologia, CSL Behring. O estudo de fase 1/2 está completo e os resultados foram publicados. Em uma amostra de 10 participantes, verificou-se que uma única infusão de etranacogene dezaparvovec teve um perfil bem tolerado e resultou em estabilidade e aumento na atividade do fator IX, uma redução acentuada em sangramentos espontâneos e uso de concentrado do fator IX em todos os participantes. Os autores observaram uma melhor resposta à dose nos participantes que receberam a dose mais alta (2x10 gc/kg). O estudo fase 2b foi realizado para confirmar a eficácia e segurança do etranacogene dezaparvovec em dose única de 2x1013 gc/kg para posterior avaliação na fase 3, uma vez que houve uma mudança de desenho da tecnologia. Com base em duas publicações e um resumo de congresso, os resultados do estudo da fase 2b que incluíram três pacientes mostraram aumentos na atividade do fator IX, cessação de sangramentos e revogação da necessidade de substituição do fator IX e um perfil de segurança bem tolerado. A consistência dos resultados suportou uma avaliação expandida da segurança/eficácia do etranacogene dezaparvovec na fase 3. Já o estudo de fase 3 (HOPE-B), com 54 participantes, está ativo, mas não recrutando. Até a última atualização deste alerta, os resultados preliminares foram divulgados em oito resumos de congresso e nos resultados disponíveis no registro do ensaio clínico. Os principais resultados de eficácia incluíram redução da taxa anual de sangramentos, aumento estável e duradouro na atividade média do fator IX e necessidade do uso da profilaxia com fator IX. Também foi observada uma melhora na qualidade de vida relacionada à saúde dos participantes. O perfil de segurança foi bem tolerado e não houve ocorrências de eventos adversos sérios ou mortes relacionadas ao tratamento. O etranacogene dezaparvovec apresenta registro no Estados Unidos e Europa com indicação inicial para tratamento de hemofilia B grave ou moderada em adultos sem histórico de inibidores do fator IX. No Brasil, a tecnologia não possui registro ou pedido de registro na Anvisa. Apesar dos resultados promissores, deve-se considerar que as evidências disponíveis sobre a eficácia e segurança do etranacogene dezaparvovec para tratamento de pacientes com hemofilia B ainda são escassas, recentes e provindas de ensaios clínicos não cegos, não randomizados, de braço único com amostras pequenas e seguimentos relativamente curtos. Apenas uma agência de Avaliação de Tecnologias em Saúde, o Institute for Clinical and Economic Review (ICER) dos Estados Unidos, deu um parecer positivo para o uso do medicamento para esta indicação. Contudo, os resultados da análise de custoefetividade demonstraram que a tecnologia não foi custo-efetiva. Não foram identificados outros ensaios clínicos em andamento. No entanto, enfatiza-se que novas evidências mais robustas são necessárias e poderão subsidiar futuras avaliações sobre a eficácia e segurança do uso do etranacogene dezaparvovec para o tratamento de Hemofilia B. Além disso, para que ocorra a oferta desse medicamento no SUS, é necessária sua análise pela Comissão Nacional de Incorporação de Tecnologias em Saúde (Conitec), conforme disposto na Lei nº 12.401/2011, que alterou a Lei nº 8.080/1990. Os relatórios de recomendação da Conitec levam em consideração as evidências científicas sobre eficácia, a acurácia, a efetividade e a segurança do medicamento, e, também, a avaliação econômica comparativa dos benefícios e dos custos em relação às tecnologias já incorporadas e o impacto da incorporação da tecnologia no SUS.

The Golgi Calcium ATPase Pump Plays an Essential Role in Adeno-associated Virus Trafficking and Transduction.

Adeno-associated viruses (AAVs) are dependoparvoviruses that have proven useful for therapeutic gene transfer; however, our understanding of host factors that influence AAV trafficking and transduction is still evolving. Here, we investigated the role of cellular calcium in the AAV infectious pathway. First, we demonstrated a critical role for the host Golgi compartment-resident ATP-powered calcium pump (secretory pathway calcium ATPase 1 [SPCA1]) encoded by the ATP2C1 gene in AAV infection. CRISPR-based knockout (KO) of ATP2C1 decreases transduction by different AAV serotypes. ATP2C1 KO does not appear to inhibit AAV binding, cellular uptake, or nuclear entry; however, capsids within ATP2C1 KO cells demonstrate dispersed and punctate trafficking distinct from the perinuclear, trans-Golgi pattern observed in normal cells. In addition, we observed a defect in the ability of AAV capsids to undergo conformational changes and support efficient vector genome transcription in ATP2C1 KO cells. The calcium chelator BAPTA-AM, which reduces cytosolic calcium, rescues the defective ATP2C1 KO phenotype and AAV transduction in vitro Conversely, the calcium ionophore ionomycin, which disrupts calcium gradients, blocks AAV transduction. Further, we demonstrated that modulating calcium in the murine brain using BAPTA-AM augments AAV gene expression in vivo Taking these data together, we postulate that the maintenance of an intracellular calcium gradient by the calcium ATPase and processing within the Golgi compartment are essential for priming the capsid to support efficient AAV genome transcription.IMPORTANCE Adeno-associated viruses (AAVs) have proven to be effective gene transfer vectors. However, our understanding of how the host cell environment influences AAV transduction is still evolving. In the present study, we investigated the role of ATP2C1, which encodes a membrane calcium transport pump, SPCA1, essential for maintaining cellular calcium homeostasis on AAV transduction. Our results indicate that cellular calcium is essential for efficient intracellular trafficking and conformational changes in the AAV capsid that support efficient genome transcription. Further, we show that pharmacological modulation of cellular calcium levels can potentially be applied to improve the AAV gene transfer efficiency.

Infectivity Assessment of Recombinant Adeno-Associated Virus and Wild-Type Adeno-Associated Virus Exposed to Various Diluents and Environmental Conditions.

Recombinant adeno-associated virus (rAAV) is a promising gene delivery vehicle that has been approved as a gene therapy drug for some genetic disorders, and is being evaluated in clinical trials. To further promote clinical research under the Food and Drug Administration Investigational New Drug application, the stability of rAAV must be assessed under various conditions. However, there is scant data concerning the stability of a variety of rAAV serotypes. We hypothesized that the difference of capsid structure causes differences in stability. To investigate this hypothesis, rAAV serotypes (rAAV1, rAAV2, rAAV8, and rAAV9) were exposed to diluents and various environmental conditions, including ultraviolet (UV) irradiation, 0.1 M sodium hydroxide (NaOH), 0.06% sodium hypochlorite (NaClO), tap water, and 70% ethanol (EtOH). The changes of the infectivity of the treated samples were assessed by transduction in HeLaRC32 cells as a criterion of stability. The infectivity between recombinant and wild-type AAV (wtAAV2) was also analyzed. The activity of all rAAV serotypes was weakened by UV irradiation and NaOH and NaClO exposure. Treatment for 10 days with tap water or 70% EtOH did not appreciably inactivate rAAV1, rAAV8, and rAAV9, but did affect the activity of rAAV2. Furthermore, the infectivity of rAAV2 did not surpass wtAAV2 infectivity. The results will be important for clinical studies for gene therapy using rAAV.

GM1 Ganglioside Modifies α-Synuclein Toxicity and is Neuroprotective in a Rat α-Synuclein Model of Parkinson's Disease.

While GM1 may interact with α-synuclein in vitro to inhibit aggregation, the ability of GM1 to protect against α-synuclein toxicity in vivo has not been investigated. We used targeted adeno-associated viral vector (AAV) overexpression of human mutant α-synuclein (A53T) in the rat substantia nigra (SN) to produce degeneration of SN dopamine neurons, loss of striatal dopamine levels, and behavioral impairment. Some animals received daily GM1 ganglioside administration for 6 weeks, beginning 24 hours after AAV-A53T administration or delayed start GM1 administration for 5 weeks beginning 3 weeks after AAV-A53T administration. Both types of GM1 administration protected against loss of SN dopamine neurons and striatal dopamine levels, reduced α-synuclein aggregation, and delayed start administration of GM1 reversed early appearing behavioral deficits. These results extend prior positive results in MPTP models, are consistent with the results of a small clinical study of GM1 in PD patients that showed slowing of symptom progression with chronic use, and argue for the continued refinement and development of GM1 as a potential disease modifying therapy for PD.

Optimization of Dexamethasone Administration for Maintaining Global Transduction Efficacy of Adeno-Associated Virus Serotype 9.

Glucocorticoids have been commonly used in clinic for their anti-inflammatory and immunosuppressive effects, and it has been proposed that they be used to prevent liver toxicity when systemic administration of adeno-associated virus (AAV) vectors is needed in patients with central nervous system diseases and muscular disorders. Glucocorticoids also enable modulation of vascular permeability. First, this study investigated the impact of dexamethasone on AAV vascular permeability after systemic injection. When a low dose of AAV9 was injected into mice treated with dexamethasone, global transduction and vector biodistribution were not significantly different in most tissues, other than the liver and the heart, when compared to control mice. When AAV9 vectors were used at a high dose, both the transgene expression and the AAV vector genome copy number were significantly decreased in the majority of murine tissues. However, no effect on global transduction was observed when dexamethasone was administered 2 h after AAV vector injection. The study on the kinetics of AAV virus clearance demonstrated that dexamethasone slowed down the clearance of AAV9 in the blood after systemic application. The mechanism study showed that dexamethasone inhibited the enhancement of AAV9 vascular permeability mediated by serum proteins. The findings indicate that dexamethasone is able to inhibit the vascular permeability of AAV and compromise the therapeutic effect after systemic administration of AAV vector. In conclusion, this study provides valuable information for the design of future clinical studies when glucocorticoids are needed to be compatible with the systemic administration of AAV vectors in patients with central nervous system and muscular diseases.

Relevance of Assembly-Activating Protein for Adeno-associated Virus Vector Production and Capsid Protein Stability in Mammalian and Insect Cells.

The discovery that adeno-associated virus 2 (AAV2) encodes an eighth protein, called assembly-activating protein (AAP), transformed our understanding of wild-type AAV biology. Concurrently, it raised questions about the role of AAP during production of recombinant vectors based on natural or molecularly engineered AAV capsids. Here, we show that AAP is indeed essential for generation of functional recombinant AAV2 vectors in both mammalian and insect cell-based vector production systems. Surprisingly, we observed that AAV2 capsid proteins VP1 to -3 are unstable in the absence of AAP2, likely due to rapid proteasomal degradation. Inhibition of the proteasome led to an increase of intracellular VP1 to -3 but neither triggered assembly of functional capsids nor promoted nuclear localization of the capsid proteins. Together, this underscores the crucial and unique role of AAP in the AAV life cycle, where it rapidly chaperones capsid assembly, thus preventing degradation of free capsid proteins. An expanded analysis comprising nine alternative AAV serotypes (1, 3 to 9, and rh10) showed that vector production always depends on the presence of AAP, with the exceptions of AAV4 and AAV5, which exhibited AAP-independent, albeit low-level, particle assembly. Interestingly, AAPs from all 10 serotypes could cross-complement AAP-depleted helper plasmids during vector production, despite there being distinct intracellular AAP localization patterns. These were most pronounced for AAP4 and AAP5, congruent with their inability to rescue an AAV2/AAP2 knockout. We conclude that AAP is key for assembly of genuine capsids from at least 10 different AAV serotypes, which has implications for vectors derived from wild-type or synthetic AAV capsids.IMPORTANCE Assembly of adeno-associated virus 2 (AAV2) is regulated by the assembly-activating protein (AAP), whose open reading frame overlaps with that of the viral capsid proteins. As the majority of evidence was obtained using virus-like particles composed solely of the major capsid protein VP3, AAP's role in and relevance for assembly of genuine AAV capsids have remained largely unclear. Thus, we established a trans-complementation assay permitting assessment of AAP functionality during production of recombinant vectors based on complete AAV capsids and derived from any serotype. We find that AAP is indeed a critical factor not only for AAV2, but also for generation of vectors derived from nine other AAV serotypes. Moreover, we identify a new role of AAP in maintaining capsid protein stability in mammalian and insect cells. Thereby, our study expands our current understanding of AAV/AAP biology, and it concomitantly provides insights into the importance of AAP for AAV vector production.

Identification and Validation of Small Molecules That Enhance Recombinant Adeno-associated Virus Transduction following High-Throughput Screens.

UNLABELLED: While the recent success of adeno-associated virus (AAV)-mediated gene therapy in clinical trials is promising, challenges still face the widespread applicability of recombinant AAV(rAAV). A major goal is to enhance the transduction efficiency of vectors in order to achieve therapeutic levels of gene expression at a vector dose that is below the immunological response threshold. In an attempt to identify novel compounds that enhance rAAV transduction, we performed two high-throughput screens comprising 2,396 compounds. We identified 13 compounds that were capable of enhancing transduction, of which 12 demonstrated vector-specific effects and 1 could also enhance vector-independent transgene expression. Many of these compounds had similar properties and could be categorized into five groups: epipodophyllotoxins (group 1), inducers of DNA damage (group 2), effectors of epigenetic modification (group 3), anthracyclines (group 4), and proteasome inhibitors (group 5). We optimized dosing for the identified compounds in several immortalized human cell lines as well as normal diploid cells. We found that the group 1 epipodophyllotoxins (teniposide and etoposide) consistently produced the greatest transduction enhancement. We also explored transduction enhancement among single-stranded, self-complementary, and fragment vectors and found that the compounds could impact fragmented rAAV2 transduction to an even greater extent than single-stranded vectors. In vivo analysis of rAAV2 and all of the clinically relevant compounds revealed that, consistent with our in vitro results, teniposide exhibited the greatest level of transduction enhancement. Finally, we explored the capability of teniposide to enhance transduction of fragment vectors in vivo using an AAV8 capsid that is known to exhibit robust liver tropism. Consistent with our in vitro results, teniposide coadministration greatly enhanced fragmented rAAV8 transduction at 48 h and 8 days. This study provides a foundation based on the rAAV small-molecule screen methodology, which is ideally used for more-diverse libraries of compounds that can be tested for potentiating rAAV transduction. IMPORTANCE: This study seeks to enhance the capability of adeno-associated viral vectors for therapeutic gene delivery applicable to the treatment of diverse diseases. To do this, a comprehensive panel of FDA-approved drugs were tested in human cells and in animal models to determine if they increased adeno-associated virus gene delivery. The results demonstrate that particular groups of drugs enhance adeno-associated virus gene delivery by unknown mechanisms. In particular, the enhancement of gene delivery was approximately 50 to 100 times better with than without teniposide, a compound that is also used as chemotherapy for cancer. Collectively, these results highlight the potential for FDA-approved drug enhancement of adeno-associated virus gene therapy, which could result in safe and effective treatments for diverse acquired or genetic diseases.

Impact of Heparan Sulfate Binding on Transduction of Retina by Recombinant Adeno-Associated Virus Vectors.

UNLABELLED: Adeno-associated viruses (AAVs) currently are being developed to efficiently transduce the retina following noninvasive, intravitreal (Ivt) injection. However, a major barrier encountered by intravitreally delivered AAVs is the inner limiting membrane (ILM), a basement membrane rich in heparan sulfate (HS) proteoglycan. The goal of this study was to determine the impact of HS binding on retinal transduction by Ivt-delivered AAVs. The heparin affinities of AAV2-based tyrosine-to-phenylalanine (Y-F) and threonine-to-valine (T-V) capsid mutants, designed to avoid proteasomal degradation during cellular trafficking, were established. In addition, the impact of grafting HS binding residues onto AAV1, AAV5, and AAV8(Y733F) as well as ablation of HS binding by AAV2-based vectors on retinal transduction was investigated. Finally, the potential relationship between thermal stability of AAV2-based capsids and Ivt-mediated transduction was explored. The results show that the Y-F and T-V AAV2 capsid mutants bind heparin but with slightly reduced affinity relative to that of AAV2. The grafting of HS binding increased Ivt transduction by AAV1 but not by AAV5 or AAV8(Y733F). The substitution of any canonical HS binding residues ablated Ivt-mediated transduction by AAV2-based vectors. However, these same HS variant vectors displayed efficient retinal transduction when delivered subretinally. Notably, a variant devoid of canonical HS binding residues, AAV2(4pMut)ΔHS, was remarkably efficient at transducing photoreceptors. The disparate AAV phenotypes indicate that HS binding, while critical for AAV2-based vectors, is not the sole determinant for transduction via the Ivt route. Finally, Y-F and T-V mutations alter capsid stability, with a potential relationship existing between stability and improvements in retinal transduction by Ivt injection. IMPORTANCE: AAV has emerged as the vector of choice for gene delivery to the retina, with attention focused on developing vectors that can mediate transduction following noninvasive, intravitreal injection. HS binding has been postulated to play a role in intravitreally mediated transduction of retina. Our evaluation of the HS binding of AAV2-based variants and other AAV serotype vectors and the correlation of this property with transduction points to HS affinity as a factor controlling retinal transduction following Ivt delivery. However, HS binding is not the only requirement for improved Ivt-mediated transduction. We show that AAV2-based vectors lacking heparin binding transduce retina by subretinal injection and display a remarkable ability to transduce photoreceptors, indicating that other receptors are involved in this phenotype.

An essential receptor for adeno-associated virus infection.

Adeno-associated virus (AAV) vectors are currently the leading candidates for virus-based gene therapies because of their broad tissue tropism, non-pathogenic nature and low immunogenicity. They have been successfully used in clinical trials to treat hereditary diseases such as haemophilia B (ref. 2), and have been approved for treatment of lipoprotein lipase deficiency in Europe. Considerable efforts have been made to engineer AAV variants with novel and biomedically valuable cell tropisms to allow efficacious systemic administration, yet basic aspects of AAV cellular entry are still poorly understood. In particular, the protein receptor(s) required for AAV entry after cell attachment remains unknown. Here we use an unbiased genetic screen to identify proteins essential for AAV serotype 2 (AAV2) infection in a haploid human cell line. The most significantly enriched gene of the screen encodes a previously uncharacterized type I transmembrane protein, KIAA0319L (denoted hereafter as AAV receptor (AAVR)). We characterize AAVR as a protein capable of rapid endocytosis from the plasma membrane and trafficking to the trans-Golgi network. We show that AAVR directly binds to AAV2 particles, and that anti-AAVR antibodies efficiently block AAV2 infection. Moreover, genetic ablation of AAVR renders a wide range of mammalian cell types highly resistant to AAV2 infection. Notably, AAVR serves as a critical host factor for all tested AAV serotypes. The importance of AAVR for in vivo gene delivery is further highlighted by the robust resistance of Aavr(-/-) (also known as Au040320(-/-) and Kiaa0319l(-/-)) mice to AAV infection. Collectively, our data indicate that AAVR is a universal receptor involved in AAV infection.

Polydopamine-Decorated Sticky, Water-Friendly, Biodegradable Polycaprolactone Cell Carriers.

A bioinspired adhesive material, polydopamine (pDA), was employed as an interfacial glue to stably immobilize human neural stem cells (hNSCs) on the external surface of biodegradable polycaprolactone (PCL) microspheres, thereby serving as versatile key systems that can be used for cell carriers. The pDA decoration on the PCL microspheres has been resulted in robust hNSC immobilization as well as proliferation on their curved surfaces. The pDA coating has transformed the hydrophobic PCL systems toward water-friendly and sticky characteristics, thereby resulting in full dispersion in aqueous solution and stable adherence onto a wet biological surface. Adeno-associated virus, a safe gene vector capable of effectively regulating cell behaviors, can be decorated on the PCL surfaces and delivered efficiently to hNSCs adhered to the microsphere exteriors. These distinctive multiple benefits of the sticky pDA microspheres can provide core technologies that can boost the therapeutic effects of cell therapy approaches.

Mechanistic insights into the enhancement of adeno-associated virus transduction by proteasome inhibitors.

Proteasome inhibitors (e.g., bortezomib, MG132) are known to enhance adeno-associated virus (AAV) transduction; however, whether this results from pleotropic proteasome inhibition or off-target serine and/or cysteine protease inhibition remains unresolved. Here, we examined recombinant AAV (rAAV) effects of a new proteasome inhibitor, carfilzomib, which specifically inhibits chymotrypsin-like proteasome activity and no other proteases. We determined that proteasome inhibitors act on rAAV through proteasome inhibition and not serine or cysteine protease inhibition, likely through positive changes late in transduction.

Silencing mutant ATXN3 expression resolves molecular phenotypes in SCA3 transgenic mice.

Spinocerebellar ataxia type 3 (SCA3) is a neurodegenerative disease caused by a polyglutamine expansion in the deubiquitinating enzyme, Ataxin-3. Currently, there are no effective treatments for this fatal disorder but studies support the hypothesis that reducing mutant Ataxin-3 protein levels might reverse or halt the progression of disease in SCA3. Here, we sought to modulate ATXN3 expression in vivo using RNA interference. We developed artificial microRNA mimics targeting the 3'-untranslated region (3'UTR) of human ATXN3 and then used recombinant adeno-associated virus to deliver them to the cerebellum of transgenic mice expressing the full human disease gene (SCA3/MJD84.2 mice). Anti-ATXN3 microRNA mimics effectively suppressed human ATXN3 expression in SCA3/MJD84.2 mice. Short-term treatment cleared the abnormal nuclear accumulation of mutant Ataxin-3 throughout the transduced SCA3/MJD84.2 cerebellum. Analysis also revealed changes in the steady-state levels of specific microRNAs in the cerebellum of SCA3/MJD84.2 mice, a previously uncharacterized molecular phenotype of SCA3 that appears to be dependent on mutant Ataxin-3 expression. Our findings support the preclinical development of molecular therapies aimed at halting the expression of ATXN3 as a viable approach to SCA3 and point to microRNA deregulation as a potential surrogate marker of SCA3 pathogenesis.

Arsenic trioxide stabilizes accumulations of adeno-associated virus virions at the perinuclear region, increasing transduction in vitro and in vivo.

Interactions with cellular stress pathways are central to the life cycle of many latent viruses. Here, we utilize adeno-associated virus (AAV) as a model to study these interactions, as previous studies have demonstrated that cellular stressors frequently increase transduction of recombinant AAV (rAAV) vectors and may even substitute for helper virus functions. Since several chemotherapeutic drugs are known to increase rAAV transduction, we investigated the effect of arsenic trioxide (As(2)O(3)), an FDA-approved chemotherapeutic agent with known effects on several other virus life cycles, on the transduction of rAAV. In vitro, As(2)O(3) caused a dose-dependent increase in rAAV2 transduction over a broad range of cell lines from various cell types and species (e.g., HEK-293, HeLa, HFF hTERT, C-12, and Cos-1). Mechanistically, As(2)O(3) treatment acted to prevent loss of virions from the perinuclear region, which correlated with increased cellular vector genome retention, and was distinguishable from proteasome inhibition. To extend our investigation of the cellular mechanism, we inhibited reactive oxygen species formation and determined that the As(2)O(3)-mediated increase in rAAV2 transduction was dependent upon production of reactive oxygen species. To further validate our in vitro data, we tested the effect of As(2)O(3) on rAAV transduction in vivo and determined that treatment initiated transgene expression as early as 2 days posttransduction and increased reporter expression by up to 10-fold. Moreover, the transduction of several other serotypes of rAAV was also enhanced in vivo, suggesting that As(2)O(3) affects a pathway used by several AAV serotypes. In summary, our data support a model wherein As(2)O(3) increases rAAV transduction both in vitro and in vivo and maintains perinuclear accumulations of capsids, facilitating productive nuclear trafficking.

Evidence for pH-dependent protease activity in the adeno-associated virus capsid.

Incubation of highly purified adeno-associated virus (AAV) capsids in vitro at pH 5.5 induced significant autocleavage of capsid proteins at several amino acid positions. No autocleavage was seen at pH 7.5. Examination of other AAV serotypes showed at least two different pH-induced cleavage patterns, suggesting that different serotypes have evolved alternative protease cleavage sites. In contrast, incubation of AAV serotypes with an external protease substrate showed that purified AAV capsid preparations have robust protease activity at neutral pH but not at pH 5.5, opposite to what is seen with capsid protein autocleavage. Several lines of evidence suggested that protease activity is inherent in AAV capsids and is not due to contaminating proteins. Control virus preparations showed no protease activity on external substrates, and filtrates of AAV virus preparations also showed no protease activity contaminating the capsids. Further, N-terminal Edman sequencing identified unique autocleavage sites in AAV1 and AAV9, and mutagenesis of amino acids adjacent to these sites eliminated cleavage. Finally, mutation of an amino acid in AAV2 (E563A) that is in a conserved pH-sensitive structural region eliminated protease activity on an external substrate but did not seem to affect autocleavage. Taken together, our data suggested that AAV capsids have one or more protease active sites that are sensitive to pH induction. Further, it appears that acidic pHs comparable to those seen in late endosomes induce a structural change in the capsid that induces autolytic protease activity. The pH-dependent protease activity may have a role in viral infection.

The identity of the cell adhesive protein substrate affects the efficiency of adeno-associated virus reverse transduction.

Delivering genes from surfaces, called substrate-mediated gene delivery or reverse transduction, is a useful method to achieve spatial localization of gene delivery. We tested the compatibility of adeno-associated virus (AAV) vectors with various cell adhesive proteins to mediate gene delivery from surfaces. Our studies demonstrate that AAV vectors can be successfully adsorbed on collagen I, elastin, and laminin substrates leading to robust gene delivery to overlying cells. Notably, AAV immobilization on laminin yields the highest efficiency of gene expression. This increased gene expression cannot be explained by increases in the levels of virus deposition, transcriptional activity of cells, or virus vector uptake into cells. Further refinement of our knowledge of AAV interactions with extracellular matrix proteins may have important implications in a variety of applications ranging from tissue engineering to in vivo gene therapy.

Adeno-associated viral vectors based on serotype 3b use components of the fibroblast growth factor receptor signaling complex for efficient transduction.

Adeno-associated virus type 3b (AAV3b) has been largely ignored by gene therapists because of the inability of vectors based on this serotype to transduce target tissues efficiently. Here we describe a phenomenon unique to AAV3b in that vectors based on this serotype mediate enhanced transduction in the presence of heparin. Among the many biological functions attributed to heparin, its interaction with, and ability to regulate, several growth factors (GFs) and growth factor receptors (GFRs) has been well characterized. Using GFR-overexpressing cell lines, soluble GFs and heparins, as well as specific GFR inhibitors, we have demonstrated a requirement for fibroblast growth factor receptor-2 (FGFR2) and FGF1 in the heparin-mediated augmentation of AAV3b vector transduction. In contrast to AAV2, we establish that heparin can be used as an adjunct with AAV3b to further increase transduction in a variety of cells and target tissues, additionally suggesting that AAV3b may be an attractive viral vector for clinical use during procedures in which heparin is used. In summary, AAV3b exhibits FGFR2-dependent, markedly enhanced transduction efficiency in the presence of heparin and FGFs, which could make it a useful vector for gene therapy in a variety of human diseases.

Transient and intensive pharmacological immunosuppression fails to improve AAV-based liver gene transfer in non-human primates.

BACKGROUND: Adeno-associated vectors (rAAV) have been used to attain long-term liver gene expression. In humans, the cellular immune response poses a serious obstacle for transgene persistence while neutralizing humoral immunity curtails re-administration. Porphobilinogen deaminase (PBGD) haploinsufficiency (acute intermittent porphyria) benefits from liver gene transfer in mouse models and clinical trials are about to begin. In this work, we sought to study in non-human primates the feasibility of repeated gene-transfer with intravenous administration of rAAV5 vectors under the effects of an intensive immunosuppressive regimen and to analyze its ability to circumvent T-cell immunity and thereby prolong transgene expression. METHODS: Three female Macaca fascicularis were intravenously injected with 1 x 10(13) genome copies/kg of rAAV5 encoding the human PBGD. Mycophenolate mofetil (MMF), anti-thymocyte immunoglobulin, methylprednisolone, tacrolimus and rituximab were given in combination during 12 weeks to block T- and B-cell mediated adaptive immune responses in two macaques. Immunodeficient and immunocompetent mice were intravenously injected with 5 x 10(12) genome copies/kg of rAAV5-encoding luciferase protein. Forty days later MMF, tacrolimus and rituximab were daily administrated to ascertain whether the immunosuppressants or their metabolites could interfere with transgene expression. RESULTS: Macaques given a rAAV5 vector encoding human PBGD developed cellular and humoral immunity against viral capsids but not towards the transgene. Anti-AAV humoral responses were attenuated during 12 weeks but intensely rebounded following cessation of the immunosuppressants. Accordingly, subsequent gene transfer with a rAAV5 vector encoding green fluorescent protein was impossible. One macaque showed enhanced PBGD expression 25 weeks after rAAV5-pbgd administration but overexpression had not been detected while the animal was under immunosuppression. As a potential explanation, MMF decreases transgene expression in mouse livers that had been successfully transduced by a rAAV5 several weeks before MMF onset. Such a silencing effect was independent of AAV complementary strand synthesis and requires an adaptive immune system. CONCLUSIONS: These results indicate that our transient and intensive pharmacological immunosuppression fails to improve AAV5-based liver gene transfer in non-human primates. The reasons include an incomplete restraint of humoral immune responses to viral capsids that interfere with repeated gene transfer in addition to an intriguing MMF-dependent drug-mediated interference with liver transgene expression.

Hoechst increases adeno-associated virus-mediated transgene expression in airway epithelia by inducing the cytomegalovirus promoter.

BACKGROUND: In airway epithelia, the kinetics of recombinant adeno-associated virus (AAV) transgene expression is slow. This has negative practical implications for research, as well as for translation into therapy. The DNA minor groove-binding agent Hoechst-33342 has been shown to enhance AAV transgene expression. In the present study, we investigated the mechanism of Hoechst-related augmentation of AAV-mediated transgene expression. METHODS: We investigated the effect of Hoechst-33342 on HT1080, COS-7, mouse and human airway epithelia transduced with different AAV serotypes encoding enhanced green fluorescent protein (eGFP). We exposed cells to increasing concentrations of Hoechst-33342 at different time points. We evaluated the effect on second-strand DNA synthesis using AAV with a self-complementary genome. We also investigated the effect on expression from transfected plasmids with and without AAV2 inverted terminal repeats (ITRs). RESULTS: We found that Hoechst-33342 significantly accelerated AAV transgene expression for all serotypes tested. Hoechst-33342 only had an effect when the treatment was given during or after transduction, even 120 days post-transduction, suggesting an effect on transgene expression regulation. Hoechst-33342 increased transgene expression when cells were transduced with a self-complementary AAV with the cytomegalovirus promoter, although there was no effect on cells transduced with conventional single-stranded AAV encoding the Rous sarcoma virus promoter. Finally, Hoechst-33342 increases gene expression from transfected plasmids regardless of the presence of AAV2 ITRs. CONCLUSIONS: Hoechst dramatically augments and accelerates AAV-mediated transgene expression in airway epithelia without altering AAV-mediated gene transfer. Hoechst activation of the cytomegalovirus promoter is seen in plasmids, although it is drastically enhanced in the context of AAV.

Rescue of dystrophic skeletal muscle by PGC-1α involves a fast to slow fiber type shift in the mdx mouse.

Increased utrophin expression is known to reduce pathology in dystrophin-deficient skeletal muscles. Transgenic over-expression of PGC-1α has been shown to increase levels of utrophin mRNA and improve the histology of mdx muscles. Other reports have shown that PGC-1α signaling can lead to increased oxidative capacity and a fast to slow fiber type shift. Given that it has been shown that slow fibers produce and maintain more utrophin than fast skeletal muscle fibers, we hypothesized that over-expression of PGC-1α in post-natal mdx mice would increase utrophin levels via a fiber type shift, resulting in more slow, oxidative fibers that are also more resistant to contraction-induced damage. To test this hypothesis, neonatal mdx mice were injected with recombinant adeno-associated virus (AAV) driving expression of PGC-1α. PGC-1α over-expression resulted in increased utrophin and type I myosin heavy chain expression as well as elevated mitochondrial protein expression. Muscles were shown to be more resistant to contraction-induced damage and more fatigue resistant. Sirt-1 was increased while p38 activation and NRF-1 were reduced in PGC-1α over-expressing muscle when compared to control. We also evaluated if the use a pharmacological PGC-1α pathway activator, resveratrol, could drive the same physiological changes. Resveratrol administration (100 mg/kg/day) resulted in improved fatigue resistance, but did not achieve significant increases in utrophin expression. These data suggest that the PGC-1α pathway is a potential target for therapeutic intervention in dystrophic skeletal muscle.

High-throughput functional microRNAs profiling by recombinant AAV-based microRNA sensor arrays.

BACKGROUND: microRNAs (miRNAs) are small and non-coding RNAs which play critical roles in physiological and pathological processes. A number of methods have been established to detect and quantify miRNA expression. However, method for high-throughput miRNA function detection is still lacking. PRINCIPAL FINDINGS: We describe an adeno-associated virus (AAV) vector-based microRNA (miRNA) sensor (Asensor) array for high-throughput functional miRNA profiling. Each Asensor contains a Gaussia luciferase (Gluc) and a firefly luciferase (Fluc) expression cassette to sense functional miRNA and to serve as an internal control respectively. Using this array, we acquired functional profiles of 115 miRNAs for 12 cell lines and found "functional miRNA signatures" for several specific cell lines. The activities of specific miRNAs including the let-7 family, miR-17-92 cluster, miR-221, and miR-222 in HEK 293 cells were compared with their expression levels determined by quantitative reverse transcriptase polymerase chain reaction (QRT-PCR). We also demonstrate two other practical applications of the array, including a comparison of the miRNA activity between HEK293 and HEK293T cells and the ability to monitor miRNA activity changes in K562 cells treated with 12-O-tetradecanoylphorbol-13-acetate (TPA). CONCLUSIONS/SIGNIFICANCE: Our approach has potential applications in the identification of cell types, the characterization of biological and pathological processes, and the evaluation of responses to interventions.