Hemophilia A gene therapy via intraosseous delivery of factor VIII-lentiviral vectors

CD14+/CD31+ monocytes expanded by UM171 correct hemophilia A in zebrafish upon lentiviral gene transfer of factor VIII

Emerging gene therapy clinical trials test the correction of hemophilia A (HA) by replacing factor VIII (FVIII) in autologous hematopoietic stem cells (HSCs). Although it is known that platelets, monocyte/macrophages, and mesenchymal stromal cells can secrete transgenic FVIII, a systematic examination of blood lineages as extrahepatic sources of FVIII, to our knowledge, has not yet been performed. In this study, we sought to provide a comprehensive map of native and lentivirus-based transgenic FVIII production from HSC stage to mature blood cells, through a flow cytometry analysis. In addition, we generated a model of transient HA in zebrafish based on antisense RNA, to assess the corrective potential of the FVIII-transduced HSCs. We discovered that FVIII production begins at the CD34+ progenitor stage after cytokine stimulation in culture. Among all mature white blood cells, monocytes are the largest producers of native FVIII and can maintain protein overexpression during differentiation from HSCs when transduced by a FVIII lentiviral vector. Moreover, the addition of the HSC self-renewal agonist UM171 to CD34+ cells during transduction expanded a subpopulation of CD14+/CD31+ monocytes with excellent ability to carry the FVIII transgene, allowing the correction of HA phenotype in zebrafish. Finally, the HA zebrafish model showed that f8 RNA is predominantly localized in the hematopoietic system at the larval stage, which indicates a potential contributory role of FVIII in hematopoiesis that warrants further investigation. We believe that this study may be of broad interest to hematologists and researchers striving to advance knowledge and permanent treatments for patients with HA.

Hemophilia a patients with inhibitors: Mechanistic insights and novel therapeutic implications

The development of coagulation factor VIII (FVIII) inhibitory antibodies is a serious complication in hemophilia A (HA) patients after FVIII replacement therapy. Inhibitors render regular prophylaxis ineffective and increase the risk of morbidity and mortality. Immune tolerance induction (ITI) regimens have become the only clinically proven therapy for eradicating these inhibitors. However, this is a lengthy and costly strategy. For HA patients with high titer inhibitors, bypassing or new hemostatic agents must be used in clinical prophylaxis due to the ineffective ITI regimens. Since multiple genetic and environmental factors are involved in the pathogenesis of inhibitor generation, understanding the mechanisms by which inhibitors develop could help identify critical targets that can be exploited to prevent or eradicate inhibitors. In this review, we provide a comprehensive overview of the recent advances related to mechanistic insights into anti-FVIII antibody development and discuss novel therapeutic approaches for HA patients with inhibitors.

Transduction of modified factor VIII gene improves lentiviral gene therapy efficacy for hemophilia A

Hemophilia A (HA) is a bleeding disorder caused by deficiency of the coagulation factor VIII (F8). F8 replacement is standard of care, whereas gene therapy (F8 gene) for HA is an attractive investigational approach. However, the large size of the F8 gene and the immunogenicity of the product present challenges in development of the F8 gene therapy. To resolve these problems, we synthesized a shortened F8 gene (F8-BDD) and cloned it into a lentiviral vector (LV). The F8-BDD produced mainly short cleaved inactive products in LV-transduced cells. To improve F8 functionality, we designed two novel F8-BDD genes, one with an insertion of eight specific N-glycosylation sites (F8-N8) and another which restored all N-glycosylation sites (F8-299) in the B domain. Although the overall protein expression was reduced, high coagulation activity (>100-fold) was detected in the supernatants of LV-F8-N8- and LV-F8-299-transduced cells. Protein analysis of F8 and the procoagulation cofactor, von Willebrand Factor, showed enhanced interaction after restoration of B domain glycosylation using F8-299. HA mouse hematopoietic stem cell transplantation studies illustrated that the bleeding phenotype was corrected after LV-F8-N8 or -299 gene transfer into the hematopoietic stem cells. Importantly, the F8-299 modification markedly reduced immunogenicity of the F8 protein in these HA mice. In conclusion, the modified F8-299 gene could be efficiently packaged into LV and, although with reduced expression, produced highly stable and functional F8 protein that corrected the bleeding phenotype without inhibitory immunogenicity. We anticipate that these results will be beneficial in the development of gene therapies against HA.

Emerging Therapeutic Modalities against COVID-19

The novel SARS-CoV-2 virus has quickly spread worldwide, bringing the whole world as well as the economy to a standstill. As the world is struggling to minimize the transmission of this devastating disease, several strategies are being actively deployed to develop therapeutic interventions. Pharmaceutical companies and academic researchers are relentlessly working to investigate experimental, repurposed or FDA-approved drugs on a compassionate basis and novel biologics for SARS-CoV-2 prophylaxis and treatment. Presently, a tremendous surge of COVID-19 clinical trials are advancing through different stages. Among currently registered clinical efforts, ~86% are centered on testing small molecules or antibodies either alone or in combination with immunomodulators. The rest ~14% of clinical efforts are aimed at evaluating vaccines and convalescent plasma-based therapies to mitigate the disease's symptoms. This review provides a comprehensive overview of current therapeutic modalities being evaluated against SARS-CoV-2 virus in clinical trials.

Advances in gene therapy for hematologic disease and considerations for transfusion medicine

As the list of regulatory agency-approved gene therapies grows, these products are now in the therapeutic spotlight with the potential to cure or dramatically alleviate several benign and malignant hematologic diseases. The mechanisms for gene manipulation are diverse, and include the use of a variety of cell sources and both viral vector- and nuclease-based targeted approaches. Gene editing has also reached the realm of blood component therapy and testing, where cultured products are being developed to improve transfusion support for individuals with rare blood types. In this review, we summarize the milestones in the development of gene therapies for hematologic diseases, mechanisms for gene manipulation, and implications for transfusion medicine and blood centers as these therapies continue to advance and grow.

Platelet-Targeted FVIII Gene Therapy Restores Hemostasis and Induces Immune Tolerance for Hemophilia A

Platelets are small anucleated blood components primarily described as playing a fundamental role in hemostasis and thrombosis. Over the last decades, increasing evidence has demonstrated the role of platelets in modulating inflammatory reactions and immune responses. Platelets harbor several specialized organelles: granules, endosomes, lysosomes, and mitochondria that can synthesize proteins with pre-stored mRNAs when needed. While the functions of platelets in the immune response are well-recognized, little is known about the potential role of platelets in immune tolerance. Recent studies demonstrate that platelet-specific FVIII gene therapy can restore hemostasis and induce immune tolerance in hemophilia A mice, even mice with preexisting anti-FVIII immunity. Here, we review the potential mechanisms by which platelet-targeted FVIII gene therapy restores hemostasis in the presence of anti-FVIII inhibitory antibodies and induces immune tolerance in hemophilia A.

Delivery of genome editing tools: A promising strategy for HPV-related cervical malignancy therapy

INTRODUCTION

Persistent high-risk human papillomavirus infection is the main cause of various types of cancer especially cervical cancer. The E6 and E7 oncoproteins of HPV play critical roles in promoting carcinogenesis and cancer cell growth. As a result, E6 and E7 oncogenes are considered as promising therapeutic targets for cervical cancer. Recently, the development of genome-editing technologies including transcription activator-like effector nucleases (TALEN), meganucleases (MNs), zinc finger nucleases (ZFN), and more importantly clustered regularly interspaced short palindromic repeat-CRISPR-associated protein (CRISPR-Cas) has sparked a revolution in the cervical cancer-targeted therapy. However, due to immunogenicity, off-target effect, renal clearance, guide RNA (gRNA) nuclease degradation, and difficult direct transportation into the cytoplasm and nucleus, the safe and effective delivery is considered as the Achilles' heel of this robust strategy.

AREAS COVERED

In this review, we discuss cutting-edge available strategies for in vivo delivery of genome-editing technologies for HPV-induced cervical cancer therapy. Moreover, the combination of genome-editing tools and other therapies has been fully discussed.

EXPERT OPINION

The combination of nanoparticle-based delivery systems and genome-editing tools is a promising powerful strategy for cervical cancer therapy. The most significant limitations of this strategy that need to be focused on are low efficiency and off-target events.

Defining the Optimal FVIII Transgene for Placental Cell-Based Gene Therapy to Treat Hemophilia A

The delivery of factor VIII (FVIII) through gene and/or cellular platforms has emerged as a promising hemophilia A treatment. Herein, we investigated the suitability of human placental cells (PLCs) as delivery vehicles for FVIII and determined an optimal FVIII transgene to produce/secrete therapeutic FVIII levels from these cells. Using three PLC cell banks we demonstrated that PLCs constitutively secreted low levels of FVIII, suggesting their suitability as a transgenic FVIII production platform. Furthermore, PLCs significantly increased FVIII secretion after transduction with a lentiviral vector (LV) encoding a myeloid codon-optimized bioengineered FVIII containing high-expression elements from porcine FVIII. Importantly, transduced PLCs did not upregulate cellular stress or innate immunity molecules, demonstrating that after transduction and FVIII production/secretion, PLCs retained low immunogenicity and cell stress. When LV encoding five different bioengineered FVIII transgenes were compared for transduction efficiency, FVIII production, and secretion, data showed that PLCs transduced with LV encoding hybrid human/porcine FVIII transgenes secreted substantially higher levels of FVIII than did LV encoding B domain-deleted human FVIII. In addition, data showed that in PLCs, myeloid codon optimization is needed to increase FVIII secretion to therapeutic levels. These studies have identified an optimal combination of FVIII transgene and cell source to achieve clinically meaningful levels of secreted FVIII.

A CRISPR/Cas9 based polymeric nanoparticles to treat/inhibit microbial infections

The latest breakthrough towards the adequate and decisive methods of gene editing tools provided by CRISPR/Cas9 (Clustered Regularly Interspaced Short Palindromic Repeat/CRISPR Associated System), has been repurposed into a tool for genetically engineering eukaryotic cells and now considered as the major innovation in gene-related disorders. Nanotechnology has provided an alternate way to overcome the conventional problems where methods to deliver therapeutic agents have failed. The use of nanotechnology has the potential to safe-side the CRISPR/Cas9 components delivery by using customized polymeric nanoparticles for safety and efficacy. The pairing of two (CRISPR/Cas9 and nanotechnology) has the potential for opening new avenues in therapeutic use. In this review, we will discuss the most recent advances in developing nanoparticle-based CRISPR/Cas9 gene editing cargo delivery with a focus on several polymeric nanoparticles including fabrication proposals to combat microbial infections.

New technologies in gene therapy for inducing immune tolerance in hemophilia A

INTRODUCTION

Conventional hemophilia treatment is based on repeated infusion of the missing clotting factor. This therapy is lifelong, expensive and can result in the formation of neutralizing antibodies, thus causing failure of the treatment and requiring higher doses of the replacement drug. Areas covered: Gene and cell therapies offer the advantage of providing a definitive and long-lasting correction of the mutated gene, promoting its physiological expression and preventing neutralizing antibody development. This review focuses on the most recent approaches that have been shown to prevent and even eradicate immune response toward the replaced factor. Expert commentary: Despite the encouraging data demonstrated by ongoing clinical trials and pre-clinical studies, more extensive investigations are necessary to establish the long-term safety and efficacy of gene therapy treatments in maintaining immune tolerance.

Projection Stereolithographic Fabrication of BMP-2 Gene-activated Matrix for Bone Tissue Engineering

Currently, sustained in vivo delivery of active bone morphogenetic protein-2 (BMP-2) protein to responsive target cells, such as bone marrow-derived mesenchymal stem cells (BMSCs), remains challenging. Ex vivo gene transfer method, while efficient, requires additional operation for cell culture and therefore, is not compatible with point-of-care treatment. In this study, two lentiviral gene constructs - (1) Lv-BMP/GFP, containing human BMP-2 and green fluorescent protein (GFP) gene (BMP group); or (2) Lv-GFP, containing GFP gene (GFP group) - were incorporated with human BMSCs into a solution of photocrosslinkable gelatin, which was then subjected to visible light-based projection stereolithographic printing to form a scaffold with desired architectures. Upon in vitro culture, compared to the GFP group, cells from BMP group showed >1,000-fold higher BMP-2 release, and the majority of them stained intensely for alkaline phosphatase activity. Real-time RT-PCR also showed dramatically increased expression of osteogenesis marker genes only in the BMP group. 3.5 months post-implantation into SCID mice, the micro-computed tomography imaging showed detectable mineralized areas only in the BMP group, which was restricted within the scaffolds. Alizarin red staining and immunohistochemistry of GFP and osteocalcin further indicated that the grafted hBMSCs, not host cells, contributed primarily to the newly formed bone.