Gene Therapy Delivery Research Articles

P-049: A ROADMAP FOR DELIVERING A GLOBALLY ACCESSIBLE GENE THERAPY

Purpose: The convergence of innovative biotechnologies is propelling the field of gene therapy with consequential implications for treating and curing genetic and infectious diseases globally. Although dozens of gene therapies for a broad range of disease areas are expected to receive regulatory approval worldwide over the next decade, patients are unlikely to receive equitable access to these medical breakthroughs. In particular, the sophisticated infrastructure required to deliver gene therapies pose critical challenges for low and middle-income countries (LMICs) seeking to integrate gene therapies into resource-constrained health systems. Without critical foresight and targeted investments across LMICs, gene therapies will perpetuate global health inequity. Materials and methods: Using gene therapies for sickle cell disease and human immunodeficiency virus (HIV) in sub-Saharan Africa as use cases, this project examined the necessary infrastructure required for effectively and sustainably delivering gene therapies in low-resource settings. Data was obtained through a series of interviews with expert stakeholders from sub-Saharan Africa, Europe, and the US. Interviewees represented multiple sectors including hospitals and community clinics, gene therapy companies, manufacturing, patient advocacy and community engagement, technical training, and global health priority setting. Interviews were supplemented with an extensive literature review. Results: An analysis of stakeholder interviews revealed the need for core infrastructure across seven thematic areas: research; engagement and education; facilities and manufacturing; information systems, workforce, regulation; and finance. Although assessed individually, these domains are interdependent, highlighting the need to invest and co-develop across all areas simultaneously and synergistically. Conclusion: Building the requisite infrastructure for delivering gene therapies is a multi-decade endeavour. This long horizon should not discourage immediate action; rather, it should be acknowledged and appreciated as an opportunity for strategic preparation assuring future success. By establishing and maintaining infrastructure across several thematic areas, countries can accelerate the development and delivery of gene therapies. Throughout this process, key steps should be taken to improve outcomes: Engage communities early and often: The process of providing gene therapies must be patient-centred. Involving communities in the design and implementation process will lead to effective therapies that are acceptable and accessible. Leverage existing infrastructure: Maximizing the impact of limited resources and removing redundancy requires integrated services, multi-use facilities, and increased coordination. Collaborate internationally: While countries in SSA build research capacity, promote private sector innovation and commercialization, and update regulatory frameworks, international collaboration will facilitate the exchange of scientific equipment, knowledge and training, and policy. Improve and adapt iteratively: The success of gene therapy hinges on iterative cycles of feedback between research and clinical deployment. Infrastructure should support the ability of scientific and societal findings to inform healthcare practices and regulations. While this study focuses on gene therapy delivery and its requisite infrastructure, considerations of health systems strengthening should remain at the forefront. The delivery of gene therapies should expand to align with health priorities set by countries (e.g., attention to non-communicable diseases). A narrow focus on gene therapies can create vertical systems of planning, management, and monitoring and evaluation that are not suited for other health areas and do not maximize the use of limited resources. The authors do not declare any conflict of interest

Non-Viral Delivery of Gene Therapy to the Tendon.

The tendon, as a compact connective tissue, is difficult to treat after an acute laceration or chronic degeneration. Gene-based therapy is a highly efficient strategy for diverse diseases which has been increasingly applied in tendons in recent years. As technology improves by leaps and bounds, a wide variety of non-viral vectors have been manufactured that attempt to have high biosecurity and transfection efficiency, considered to be a promising treatment modality. In this review, we examine the unwanted biological barriers, the categories of applicable genes, and the introduction and comparison of non-viral vectors. We focus on lipid-based nanoparticles and polymer-based nanoparticles, differentiating between them based on their combination with diverse chemical modifications and scaffolds.

ALPPL2‐Binding Peptide Facilitates Targeted mRNA Delivery for Efficient Hepatocellular Carcinoma Gene Therapy

AbstractmRNA‐based gene therapy has emerged as an advanced strategy for hepatocellular carcinoma (HCC) treatment. However, one of its main limitations is lacking delivery precision in vivo. Distinguishing HCC cells from other tissues is crucial for maintaining the high stability, positive therapeutic outcomes, and safety of mRNA therapeutics. Here, a novel HCC specific peptide HCC167 is developed by phage display. It is shown that the HCC167 peptide can specifically recognize variety of HCC substrates including patient samples with high affinity. Modifying nanoparticles with the HCC167 peptide facilitates an effective HCC active targeting ability. When loading with Bims‐encoding mRNA, the systemically administrated DMP‐HCC167/Bims complex efficiently suppresses HCC progression in multiple models including patient‐derived xenografts. Furthermore, the ALPPL2 protein is identified as a specific binding receptor of the HCC167 peptide on the HCC cell membrane, uncovering a new active targeting mechanism based on the HCC167‐ALPPL2 ligand–receptor complex. The binding structure is also investigated by computer‐aided modeling. The study hence exhibits a potent active targeting strategy for mRNA‐based HCC therapy.

Timing is everything: Clinical evidence supports pre-symptomatic treatment for spinal muscular atrophy

Two new studies by Strauss et al. demonstrated safe and effective pre-symptomatic delivery of gene therapy in children with spinal muscular atrophy (SMA).1,2 These results highlight the importance of newborn screening programs and early therapy delivery for SMA.

Secretion of functional α1-antitrypsin is cell type dependent: Implications for intramuscular delivery for gene therapy

Heterologous expression of proteins is used widely for the biosynthesis of biologics, many of which are secreted from cells. In addition, gene therapy and messenger RNA (mRNA) vaccines frequently direct the expression of secretory proteins to nonnative host cells. Consequently, it is crucial to understand the maturation and trafficking of proteins in a range of host cells including muscle cells, a popular therapeutic target due to the ease of accessibility by intramuscular injection. Here, we analyzed the production efficiency for α1-antitrypsin (AAT) in Chinese hamster ovary cells, commonly used for biotherapeutic production, and myoblasts (embryonic progenitor cells of muscle cells) and compared it to the production in the major natural cells, liver hepatocytes. AAT is a target protein for gene therapy to address pathologies associated with insufficiencies in native AAT activity or production. AAT secretion and maturation were most efficient in hepatocytes. Myoblasts were the poorest of the cell types tested; however, secretion of active AAT was significantly augmented in myoblasts by treatment with the proteostasis regulator suberoylanilide hydroxamic acid, a histone deacetylase inhibitor. These findings were extended and validated in myotubes (mature muscle cells) where AAT was transduced using an adeno-associated viral capsid transduction method used in gene therapy clinical trials. Overall, our study sheds light on a possible mechanism to enhance the efficacy of gene therapy approaches for AAT and, moreover, may have implications for the production of proteins from mRNA vaccines, which rely on the expression of viral glycoproteins in nonnative host cells upon intramuscular injection.

Co-delivery of Bcl-2 siRNA and doxorubicin through gold nanoparticle-based delivery system for a combined cancer therapy approach

Combinational gene and chemo-therapy approach has been investigated for more effective treatment of cancer. In this report, we demonstrated a multifunctional carrier system based on gold nanoparticles (AuNPs) for co-delivery of siRNAs against Bcl-2, an anti-apoptotic gene, and doxorubicin (Dox), a well-known chemotherapy drug, to obtain enhanced treatment efficacy against advanced breast cancer. Bcl-2-siRNAs were attached to the surface of 13 nm AuNPs, and Dox was directly intercalated to the siRNA molecules without any need for complex chemical modifications or coating. Successful loading of both siRNA and Dox therapeutics to AuNPs and formation of multipurpose carrier system were demonstrated. Dox-loaded carrier system exhibited cytotoxic effect on triple-negative breast cancer (TNBC) cells and provided efficient drug internalization. Moreover, enhanced apoptosis and inhibition of cancer cell proliferation were achieved with dual delivery of Bcl-2 siRNA and Dox by the co-delivery AuNPs system. In addition, silencing of the Bcl-2 gene along with chemotherapy provided reduced colony formation and cell migration of breast cancer cells. In conclusion, inhibition of Bcl-2 expression increased the therapeutic activity of Dox on TNBC. Nevertheless, our nano-carrier system has also been tested against MCF7 cell line. Our results demonstrated that the prepared multifunctional delivery system presented an effective vehicle for simultaneous delivery of gene therapy and chemotherapy agents.

Delivering the Promise of Gene Therapy with Nanomedicines in Treating Central Nervous System Diseases.

Central Nervous System (CNS) diseases, such as Alzheimer's diseases (AD), Parkinson's Diseases (PD), brain tumors, Huntington's disease (HD), and stroke, still remain difficult to treat by the conventional molecular drugs. In recent years, various gene therapies have come into the spotlight as versatile therapeutics providing the potential to prevent and treat these diseases. Despite the significant progress that has undoubtedly been achieved in terms of the design and modification of genetic modulators with desired potency and minimized unwanted immune responses, the efficient and safe in vivo delivery of gene therapies still poses major translational challenges. Various non‐viral nanomedicines have been recently explored to circumvent this limitation. In this review, an overview of gene therapies for CNS diseases is provided and describes recent advances in the development of nanomedicines, including their unique characteristics, chemical modifications, bioconjugations, and the specific applications that those nanomedicines are harnessed to deliver gene therapies.

Tropism of the Novel AAVBR1 Capsid Following Subretinal Delivery.

A serious limitation of current adeno-associated viral (AAV) capsids employed for subretinal delivery is achieving adequate lateral spread beyond the injection site, required for the efficient delivery of gene therapy to the outer retina and/or RPE. AAVBR1 is a unique AAV with exceptional tropism for CNS microvasculature following systemic delivery. Here, we used in vivo and ex vivo analysis to show that subretinal delivery of AAVBR1.GFP in mice achieves superior tropism to RPE and outer retina than either AAV2.GFP or AAV8.GFP, two of the most common capsids used for subretinal delivery. At a low (5 × 108 vg) subretinal dose, the AAVBR1.GFP signal was visible by 48 h and significantly surpassed peak fluorescence of other AAVs in retina and RPE. The co-injection of AAVBR1.GFP with the AAVBR1-specific heptapeptide, NRGTEWD, significantly blocked the AAVBR1.GFP signal, but had no effect on AAV2.GFP fluorescence, confirming that AAVBR1’s enhanced tropism for RPE and outer retina derives from this 7AA modification within the capsid-binding motif. Enhanced dispersal and consequent transduction suggest that AAVBR1 can be employed at a lower dosage than the standard AAV2 capsid to achieve equivalent expression for gene therapy, warranting further evaluation of its utility as a therapeutic vehicle for subretinal delivery.

Update on the Corneal Dystrophies-Genetic Testing and Therapy.

One major purpose of the IC3D Corneal Dystrophy Nomenclature Revision was to include genetic information with a goal of facilitating investigation into the pathogenesis, treatment, and perhaps even prevention of the corneal dystrophies, an ambitious goal. Over a decade has passed since the first publication of the IC3D Corneal Dystrophy Nomenclature Revision. Gene therapy is available for an early-onset form of inherited retinal degeneration called Leber congenital amaurosis, but not yet for corneal degenerations. We review the current state of affairs regarding our original ambitious goal. We discuss genetic testing, gene therapy [RNA interference (RNAi) and genome editing], and ocular delivery of corneal gene therapy for the corneal dystrophies. Why have gene therapy techniques not yet been introduced for the corneal dystrophies?

Inhaled Gold Nano-star Carriers for Targeted Delivery of Triple Suicide Gene Therapy and Therapeutic MicroRNAs to Lung Metastases: Development and Validation in a Small Animal Model.

Pulmonary metastases pose significant treatment challenges for many cancers, including triple-negative breast cancer (TNBC). We developed and tested a novel suicide gene and therapeutic microRNAs (miRs) combination therapy against lung metastases in vivo in mouse models after intranasal delivery using nontoxic gold nanoparticles (AuNPs) formulated to carry these molecular therapeutics. We used AuNPs coated with chitosan-β-cyclodextrin (CS-CD) and functionalized with a urokinase plasminogen activator (uPA) peptide to carry triple cancer suicide genes (thymidine kinase-p53-nitroreductase: TK-p53-NTR) plus therapeutic miRNAs (antimiR-21, antimiR-10b and miR-100). We synthesized three AuNPs: 20nm nanodots (AuND), and 20nm or 50nm nanostars (AuNS), then surface coated these with CS-CD using a microfluidic-optimized method. We sequentially coated the resulting positively charged AuNP-CS-CD core with synthetic miRNAs followed by TK-p53-NTR via electrostatic interactions, and added uPA peptide through CD-adamantane host-guest chemistry. A comparison of transfection efficiencies for different AuNPs showed that the 50nm AuNS allowed ∼4.16-fold higher gene transfection than other NPs. The intranasal delivery of uPA-AuNS-TK-p53-NTR-microRNAs NPs (pAuNS@TK-p53-NTR-miRs) in mice predominantly accumulated in lungs and facilitated ganciclovir and CB1954 prodrug-mediated gene therapy against TNBC lung metastases. This new nanosystem may serve as an adaptable-across-cancer-type, facile, and clinically scalable platform to allow future inhalational suicide gene-miR combination therapy for patients harboring pulmonary metastases.

Pluripotent Stem Cells in Clinical Setting-New Developments and Overview of Current Status.

The number of clinical trials using human pluripotent stem cells (hPSC)—both embryonic and induced pluripotent stem cells (hESC/iPSC)—has expanded in the last several years beyond expectations. By the end of 2021, a total of 90 trials had been registered in 13 countries with more than 3000 participants. However, only US, Japan, China, and the UK are conducting both hESC- and hiPSC-based trials. Together US, Japan, and China have registered 78% (70 out of 90) of all trials worldwide. More than half of all trials (51%) are focused on the treatment of degenerative eye diseases and malignancies, enrolling nearly 2/3 of all participants in hPSC-based trials. Although no serious adverse events resulting in death or morbidity due to hPSC-based cellular therapy received have been reported, information about safety and clinical efficacy are still very limited. With the availability of novel technologies for precise genome editing, a new trend in the development of hPSC-based cellular therapies seems to be emerging. Engineering universal donor hPSC lines has become a holy grail in the field. Indeed, because of its effectiveness and simplicity nanomedicine and in vivo delivery of gene therapy could become more advantageous than cellular therapies for the treatment of multiple diseases. In the future, for the best outcome, hPSC-based cellular therapy might be combined with other technological advancements, such as biomimetic epidural electrical stimulation that can restore trunk and leg motor functions after complete spinal injury.

Convection-delivered adenoviral gene therapy reprograms the immunosuppressive glioblastoma microenvironment.

2039 Background: Immune checkpoint inhibition has not improved outcomes for glioblastoma patients, and single- cell approaches reveal the glioblastoma microenvironment is largely comprised of immunosuppressive cells. We hypothesized intratumor convection enhanced delivery (CED) of adenoviral gene therapy could recruit and activate anti-tumor immune cells in the glioblastoma microenvironment. Methods: Syngeneic GL261 (3x105 cells/mouse) or SB28 glioblastoma (3 x 104) cells were implanted into the frontal lobe of immunocompetent C57BL/6J mice (18 mice/arm). Intracranial bioluminescence (BLI) and body weight (BW) measurements were used to assess glioblastoma growth and treatment toxicity, respectively. After tumor engraftment, glioblastomas were treated with conformal ionizing radiation mimicking stereotactic radiosurgery (SRS) in human patients as a positive control for tumor inhibition (18Gy/1Fx). Attenuated adeno-associated virus 9 (AAV9) vectors encoding Gfp as a negative control, or encoding experimental cytokines driving recruitment and activation of anti-tumor immune cells in other intracranial tumors ( Ccl4, Il1b, or Apoa1) were delivered using CED (2x1011 vg/mouse). Glioblastomas were collected for histologic, single-cell, and molecular analyses 5 days after treatment (6 mice/arm) and at endpoints after monitoring for survival (12 mice/arm). CED targeting was validated using AAV9-GFP and confocal microscopy. Treatment responses were assessed using H&E, IHC, multiplexed cytokine assays, and single cell mass cytometry (CyTOF) to define immune cell types in the glioblastoma microenvironment. Results: Histologic analyses revealed AAV9-CCL4, AAV9-IL1B, or SRS induced glioblastoma macrophage infiltration, and AAV9-IL1B, AAV9-APOA1, or SRS induced glioblastoma T cell infiltration. AAV9-APOA1 (18.5 days versus 15 days, p < 0.001) or AAV9-IL1B (16.5 days versus 15 days, p = 0.001) CED treatments prolonged median survival from SB28 allografts. Glioblastoma cytokine analysis revealed inhibition of pro-tumor cytokines (IL6, LIF) after experimental CED treatments. Systemic cytokines were minimally changed by CED treatments. CyTOF showed decreased immunosuppressive macrophage infiltration and increased CD8+ T cell or microglia infiltration of the glioblastoma microenvironment after experimental CED treatments. There was no evidence of systemic or central toxicity in any treatment condition. Conclusions: Convection-enhanced delivered of adenoviral gene therapy reprograms the glioblastoma immune microenvironment and improves survival in an immunologically “cold” syngeneic glioblastoma model.

Bioprocess characterization of virus‐like particle production with the insect cell baculovirus expression system at nanoparticle level

AbstractBackground. Virus‐like particles (VLPs) are a multivalent platform showing great promise for the development of vaccines, gene therapy, diagnostic, and drug delivery approaches. Particularly, HIV‐1 Gag VLPs provide a robust and flexible scaffold for the presentation of a variety of antigens. The insect cell baculovirus expression vector system (BEVS) is nowadays one of the reference systems to produce these complex nanoparticles, but information about VLP quality, quantity, stability, as well as cell performance is scarce, especially at bioreactor scale. Results. VLPs produced in the reference High Five and Sf9 insect cell lines share similar physicochemical properties, with VLPs produced in Sf9 cells showing lower levels of double stranded DNA and protein contaminants, and a higher degree of VLP assembly. Besides VLPs, other nanoparticle populations are divergently encountered in each cell line. Hi5 supernatants contain a higher load of extracellular vesicles, while Sf9 supernatants exhibit higher concentrations of baculovirus particles. Similar titers are achieved when comparing Gag to Gag‐eGFP VLP production, with the size of most of the nanoparticles produced comprised at the 150–250 nm range. Eventually, Gag VLP production in a 2 L stirred tank bioreactor is successfully demonstrated, validating bioprocess transference to the final product candidate. Conclusions. This work provides two potentially valuable strategies for the production of HIV‐1 Gag VLPs and a detailed analysis of the different nanoparticle populations produced. © 2022 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).

Magnetite Nanoparticles in Magnetic Hyperthermia and Cancer Therapies: Challenges and Perspectives.

Until now, strategies used to treat cancer are imperfect, and this generates the need to search for better and safer solutions. The biggest issue is the lack of selective interaction with neoplastic cells, which is associated with occurrence of side effects and significantly reduces the effectiveness of therapies. The use of nanoparticles in cancer can counteract these problems. One of the most promising nanoparticles is magnetite. Implementation of this nanoparticle can improve various treatment methods such as hyperthermia, targeted drug delivery, cancer genotherapy, and protein therapy. In the first case, its feature makes magnetite useful in magnetic hyperthermia. Interaction of magnetite with the altered magnetic field generates heat. This process results in raised temperature only in a desired part of a patient body. In other therapies, magnetite-based nanoparticles could serve as a carrier for various types of therapeutic load. The magnetic field would direct the drug-related magnetite nanoparticles to the pathological site. Therefore, this material can be used in protein and gene therapy or drug delivery. Since the magnetite nanoparticle can be used in various types of cancer treatment, they are extensively studied. Herein, we summarize the latest finding on the applicability of the magnetite nanoparticles, also addressing the most critical problems faced by smart nanomedicine in oncological therapies.

Advances in Stem Cell Therapies for Rotator Cuff Injuries.

Rotator cuff injury is a common upper extremity musculoskeletal disease that may lead to persistent pain and functional impairment. Despite the clinical outcomes of the surgical procedures being satisfactory, the repair of the rotator cuff remains problematic, such as through failure of healing, adhesion formation, and fatty infiltration. Stem cells have high proliferation, strong paracrine action, and multiple differentiation potential, which promote tendon remodeling and fibrocartilage formation and increase biomechanical strength. Additionally, stem cell-derived extracellular vesicles (EVs) can increase collagen synthesis and inhibit inflammation and adhesion formation by carrying regulatory proteins and microRNAs. Therefore, stem cell-based therapy is a promising therapeutic strategy that has great potential for rotator cuff healing. In this review, we summarize the advances of stem cells and stem cell-derived EVs in rotator cuff repair and highlight the underlying mechanism of stem cells and stem cell-derived EVs and biomaterial delivery systems. Future studies need to explore stem cell therapy in combination with cellular factors, gene therapy, and novel biomaterial delivery systems.

Robust AAV Genotyping Based on Genetic Distances in Rep Gene That Are Maintained by Ubiquitous Recombination.

Adeno-associated viruses (AAVs) are a convenient tool for gene therapy delivery. According to the current classification, they are divided into the species AAV A and AAV B within the genus Dependoparvovirus. Historically AAVs were also subdivided on the intraspecies level into 13 serotypes, which differ in tissue tropism and targeted gene delivery capacity. Serotype, however, is not a universal taxonomic category, and their assignment is not always robust. Cross-reactivity has been shown, indicating that classification could not rely on the results of serological tests alone. Moreover, since the isolation of AAV4, all subsequent AAVs were subdivided into serotypes based primarily on genetic differences and phylogenetic reconstructions. An increased interest in the use of AAV as a gene delivery tool justifies the need to improve the existing classification. Here, we suggest genotype-based AAV classification below the species level based on the rep gene. A robust threshold was established as 10% nt differences within the 1248 nt genome fragment, with 4 distinct AAV genotypes identified. This distinct sub-species structure is maintained by ubiquitous recombination within, but not between, rep genes of the suggested genotypes.

Transdermal delivery for gene therapy.

Gene therapy is a critical constituent of treatment approaches for genetic diseases and has gained tremendous attention. Treating and preventing diseases at the genetic level using genetic materials such as DNA or RNAs could be a new avenue in medicine. However, delivering genes is always a challenge as these molecules are sensitive to various enzymes inside the body, often produce systemic toxicity, and suffer from off-targeting problems. In this regard, transdermal delivery has emerged as an appealing approach to enable a high efficiency and low toxicity of genetic medicines. This review systematically summarizes outstanding transdermal gene delivery methods for applications in skin cancer treatment, vaccination, wound healing, and other therapies.Graphical abstract

Recent Advances of Tumor Therapy Based on the CD47-SIRPα Axis.

Cancer is still a major disease that is currently difficult for humans to overcome. When the expression of the cluster of differentiation 47 (CD47) is upregulated, tumor cells interact with the macrophage inhibitory receptor signal regulatory protein α (SIRPα) to transmit the "Don't eat me" signal, thereby avoiding phagocytosis by the macrophages. Therefore, when the CD47-SIRPα axis is inhibited, the macrophages' phagocytic function can be restored and can also exert antitumor effects. This Review mainly introduces recent advances in tumor therapy targeted on the CD47-SIRPα axis, including the antibody and fusion protein, small molecule, gene therapy, cell therapy, and drug delivery system, to inhibit the function of CD47 expressed on tumor cells and promote tumor phagocytosis by macrophages. In addition, this Review also summarizes the current approaches to avoid anemia, a common side effect of CD47-SIRPα inhibitions, and provides ideas for clinical transformation.

Microbubble drug conjugate and focused ultrasound blood brain barrier delivery of AAV-2 SIRT-3

Background Delivery of viral vectors as gene therapies to treat neurodegenerative diseases has been hampered by the inability to penetrate the blood brain barrier (BBB) and invasive or non-targeted delivery options prone to inducing immune responses. MR guided focused ultrasound (MR-g-FUS) and microbubbles have demonstrated safe, temporary, targeted BBB permeabilization clinically. Methods We developed clinically scalable, microbubble drug conjugates (MDCs) for the viral gene therapy, AAV.SIRT3-myc [adeno-associated virus expressing myc-tagged SIRT3], which has previously been shown to have disease modifying effects in animal models of Parkinson’s disease (PD). The lipid shells of the perfluorocarbon gas MDCs were covalently conjugated to antibodies with binding specificity to AAVs. Following systemic (iv) delivery of AAV.SIRT3-myc MDCs, MR-g-FUS was used to deliver SIRT3-myc to brain regions affected in PD. SIRT3-myc expression was determined post mortem, using immunohistochemistry. Results An in vitro, SH-SY5Y cell culture model was used to show that the localized destruction of MDCs using ultrasound exposures within biological safety limits dissociated AAV2-GFP (green fluorescent protein) from the MDCs in the targeted area while maintaining their transduction capacity. In rats, MR-g-FUS resulted in BBB permeabilization in the striatum and substantia nigra (SNc). SIRT3-myc was expressed in the striatum, but not the SNc. Conclusion These studies demonstrate that MDCs combined with MR-g-FUS are an effective method for delivery of viral vector gene therapies, such as AAV.SIRT3, to brain regions affected in PD. This technology may prove useful as a disease-modifying strategy in PD and other neurodegenerative disorders.

Retention and Fouling during Nanoparticle Filtration: Implications for Membrane Purification of Biotherapeutics.

One major challenge in the development of nanoparticle-based therapeutics, including viral vectors for the delivery of gene therapies, is the development of cost-effective purification technologies. The objective of this study was to examine fouling and retention behaviors during the filtration of model nanoparticles through membranes of different pore sizes and the effect of solution conditions. Data were obtained with 30 nm fluorescently labeled polystyrene latex nanoparticles using both cellulosic and polyethersulfone membranes at a constant filtrate flux, and both pressure and nanoparticle transmission were evaluated as a function of cumulative filtrate volume. The addition of NaCl caused a delay in nanoparticle transmission and an increase in fouling. Nanoparticle transmission was also a function of particle hydrophobicity. These results provide important insights into the factors controlling transmission and fouling during nanoparticle filtration as well as a framework for the development of membrane processes for the purification of nanoparticle-based therapeutics.