Biology subjects

Valton, J.

Publications and source records attributed to Valton, J..

4 recordsLinked to original sources

bioRxiv2025

Circularization of Single-Stranded DNA Donor Template Unleashes the Power of Non-Viral Gene Delivery for Long-Term HSCs editing

Over the past decade, non-viral DNA template delivery has been used with engineered nucleases to target single-stranded DNA sequences in hematopoietic stem and progenitor cells. While effective for gene therapy, this method has been limited to short DNA donor templates, restricting its applications to gene corrections. To expand its scope, we developed an editing process using kilobase-long circular single-stranded DNA donor templates and TALEN technology. Our results show that the CssDNA editing process achieves high gene insertion frequency in viable HSPCs. Compared to a conventional AAV-editing process, CssDNA-edited HSPCs show a higher propensity to engraft and maintain gene edits in a murine model. This positive outcome is partly due to higher levels of primitive edited HSPCs, a more quiescent metabolic state, and elevated expression of bone marrow niche adhesion markers. Our findings highlight the strong potential of CssDNA as a universal and efficient non-viral DNA template for gene therapy applications.

bioengineering↗

bioRxiv2024

TALEN-mediated intron editing of HSPCs enables transgene expression restricted to the myeloid lineage

Gene therapy in hematopoietic stem and progenitor cells (HSPCs) shows great potential for the treatment of inborn metabolic diseases. Typical HSPC gene therapy approaches rely on constitutive promoters to express a therapeutic transgene, which is associated with multiple disadvantages. Here, we propose a novel promoter-less intronic gene editing approach that triggers transgene expression only after cellular differentiation into the myeloid lineage. We integrated a splicing-competent eGFP cassette into the first intron of CD11b and observed expression of eGFP in the myeloid lineage but minimal to no expression in HSPCs or differentiated non-myeloid lineages. In vivo, edited HSPCs successfully engrafted in immunodeficient mice and displayed transgene expression in the myeloid compartment of multiple tissues. Using the same approach, we expressed alpha-L-iduronidase (IDUA), the defective enzyme in Mucopolysaccharidosis type I, and observed a 10-fold supraendogenous IDUA expression exclusively after myeloid differentiation. Edited cells efficiently populated bone marrow, blood, and spleen of immunodeficient mice, and retained the capacity to secrete IDUA ex vivo. Importantly, cells edited with the eGFP and IDUA transgenes were also found in the brain. This approach may unlock new therapeutic strategies for inborn metabolic and neurological diseases that require the delivery of therapeutics in brain.

bioengineering↗

bioRxiv2023

Stromal depletion by TALEN-edited universal hypoimmunogenic FAP-CAR T cells enables infiltration and anti-tumor cytotoxicity of tumor antigen-targeted CAR-T immunotherapy.

Adoptive cell therapy based on chimeric antigen receptor-engineered T (CAR-T) cells has proven to be lifesaving for many cancer patients. However, its therapeutic efficacy has so far been restricted to only a few malignancies, with solid tumors proving to be especially recalcitrant to efficient therapy. Poor intra-tumor infiltration by T cells and T cell dysfunction due to a desmoplastic, immunosuppressive microenvironment are key barriers for CAR T-cell success against solid tumors. Cancer-associated fibroblasts (CAFs) are critical components of the tumor stroma, evolving specifically within the tumor microenvironment in response to tumor cell cues. The CAF secretome is a significant contributor to the extracellular matrix and a plethora of cytokines and growth factors that induce immune suppression. Together they form a physical and chemical barrier which induces a T cell-excluding cold TME. CAF depletion in stroma rich solid tumors can thus provide an opportunity to convert immune evasive tumors susceptible to tumor-antigen CAR T-cell cytotoxicity. Using our TALEN-based gene editing platform we engineered non-alloreactive, immune evasive CAR T-cells (termed UCAR T-cells) targeting the unique CAF marker Fibroblast Activation Protein, alpha (FAP). In an orthotopic mouse model of triple-negative breast cancer (TNBC) composed of patient derived-CAFs and tumor cells, we demonstrate the efficacy of our engineered FAP UCAR T-cells in CAF depletion, reduction of desmoplasia and successful tumor infiltration. Furthermore, while previously resistant, pre-treatment with FAP UCAR T-cells now sensitized these tumors to Mesothelin (Meso) UCAR T-cell infiltration and anti-tumor cytotoxicity. Combination therapy of FAP UCAR, Meso UCAR T cells and the checkpoint inhibitor anti-PD-1 significantly reduced tumor burden and prolonged mice survival. Our study thus proposes a novel treatment paradigm for successful CAR-T immunotherapy against stroma-rich solid tumors.

cancer biology↗

bioRxiv2021

Endowing Universal CAR T-cell with Immune-Evasive Properties using TALEN-Gene Editing.

Universal CAR T-cell therapies are poised to revolutionize cancer treatment and to improve patient outcomes. However, realizing these advantages in an allogeneic setting requires universal CAR T-cells that can kill target tumor cells, avoid depletion by the host immune system, and proliferate without attacking host tissues. Here, we describe the development of a novel immune-evasive CAR T-cells scaffold that evades NK cell and alloresponsive T-cell attacks and imparts efficient antitumor activity in vitro and in vivo. This scaffold could enable the broad use of universal CAR T-cells in allogeneic settings and holds great promise for future powerful clinical applications.

immunology↗