Publications by authors named "Brugman M"

Article Synopsis
  • Regulators and industry experts are looking for better ways to assess the cancer-causing potential of gene therapies, as current methods may not be sufficient.
  • A meeting in London in March 2023 brought together specialists to reach a consensus on key themes such as vector genotoxicity, uncertainty sources, and appropriate toxicological endpoints for gene therapy evaluation.
  • The recommendations from this meeting aim to guide the creation of new regulatory guidelines for the nonclinical toxicological assessment of gene therapy products.
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The antitumor activity of adoptive T cell therapies (ACT) is highly dependent on the expansion, persistence, and continued activity of adoptively transferred cells. Clinical studies using ACTs have revealed that products that possess and maintain less differentiated phenotypes, including memory and precursor T cells, show increased antitumor efficacy and superior patient outcomes owing to their increased expansion, persistence, and ability to differentiate into effector progeny that elicit antitumor responses. Strategies that drive the differentiation into memory or precursor-type T cell subsets with high potential for persistence and self-renewal will enhance adoptively transferred T cell maintenance and promote durable antitumor efficacy.

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Genetic modification of cells using viral vectors has shown huge therapeutic benefit in multiple diseases. However, inefficient transduction contributes to the high cost of these therapies. Several transduction-enhancing small molecules have previously been identified; however, some may be toxic to the cells or patient, otherwise alter cellular characteristics, or further increase manufacturing complexity.

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Retroviral insertional mutagenesis (RIM) is both a relevant risk in gene therapy and a powerful tool for identifying genes that enhance the competitiveness of repopulating hematopoietic stem and progenitor cells (HSPCs). However, focusing only on the gene closest to the retroviral vector insertion site (RVIS) may underestimate the effects of RIM, as dysregulation of distal and/or multiple genes by a single insertion event was reported in several studies. As a proof of concept, we examined the common insertion site (CIS) , which revealed seven genes located within ±150 kb from the RVIS for our study.

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Article Synopsis
  • The study presents a method to create stable suspension cell lines from 293T cells that produce lentiviral vectors using a single DNA construct, which simplifies the production process compared to the traditional method involving multiple plasmids.
  • These new cell lines can achieve high yields comparable to those from transient transfection and are designed to be easily scaled up in bioreactors, promoting efficient large-scale production.
  • By streamlining the production process and improving stability and yield, this approach aims to enhance patient access to therapies developed using lentiviral vectors.
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T cell factor 1 (Tcf1) is the first T cell-specific protein induced by Notch signaling in the thymus, leading to the activation of two major target genes, and . Tcf1 deficiency results in partial arrests in T cell development, high apoptosis, and increased development of B and myeloid cells. Phenotypically, seemingly fully T cell-committed thymocytes with Tcf1 deficiency have promiscuous gene expression and an altered epigenetic profile and can dedifferentiate into more immature thymocytes and non-T cells.

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Article Synopsis
  • - The study develops a new lentiviral vector (LTR1) that significantly reduces the amount of wild-type HIV-1 sequences in its genomic RNA, from 19.6% to 4.8%, to enhance safety for clinical applications.
  • - LTR1 is designed to avoid copying HIV-1 packaging sequences by using a modified single strand transfer method during reverse-transcription, thus reducing risks associated with HIV-1 remobilization and integration into human genes.
  • - The new vector shows improved performance in gene therapy, achieving more rapid transgene expression and higher levels of sustained expression in animal models, effectively treating a mouse model of hemophilia B.
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  • - Refractory celiac disease type II (RCDII) is a serious form of celiac disease characterized by abnormal lymphocytes in the intestine, which can lead to lymphoma in about half of the patients.
  • - The survival of these abnormal lymphocytes is driven by IL-15 from epithelial cells, and recent findings show that gluten-specific CD4 T cells can also promote their proliferation through cytokines like TNF, IL-2, and IL-21.
  • - Researchers found that targeting specific signaling pathways (JAK/STAT and PI3K/Akt/mTOR) can block the proliferation induced by these cytokines, indicating that CD4 T-cell responses play a significant role in the development of RCDII and
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  • LMO2 overexpression is linked to T-cell acute lymphoblastic leukemia (T-ALL) but its exact mechanisms are not fully understood.
  • In a humanized mouse model, LMO2 overexpression significantly impacts human T-cell development, particularly at the double-negative/immature single-positive stage.
  • Analysis revealed that LMO2 alters the T-cell lineage by causing an accumulation of certain T-cell types and may contribute to T-ALL leukemogenesis, correlating well with findings in human T-ALL patient samples.
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Article Synopsis
  • Canonical Wnt signaling is essential for the self-renewal of stem cells, but in the blood system, high Wnt signals can reduce their reconstituting ability.
  • Research using Apc mutant alleles demonstrated that elevated Wnt levels in hematopoietic stem cells (HSCs) promote differentiation and decrease proliferation, ultimately leading to a loss of stem cell characteristics.
  • The study sheds light on how APC mutations and Wnt signaling impact HSC biology, which could inform future clinical strategies for stem cell expansion.
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Article Synopsis
  • * Research is focusing on the developmental checkpoints that govern T cell differentiation from these stem cells, with significant advances made using various laboratory techniques.
  • * Recent studies utilizing human cells, particularly from patients with severe combined immunodeficiency, have shed light on thymic seeding processes and the clonal makeup of the thymus.
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  • The study investigates how hematopoietic stem cells (HSC) and their descendants populate the thymus, which is crucial for T-cell development, especially in the context of HSC transplantation.
  • It highlights that using umbilical cord blood for HSC transplantation often leads to insufficient T-cell recovery, emphasizing the need to understand thymic reconstitution.
  • Findings reveal that a small number of HSC clones contribute to thymic repopulation, but diverse T-cell receptors can still arise, indicating that issues with immune function after transplantation are more tied to processes within the thymus rather than the limited number of HSCs transplanted.
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  • Severe combined immunodeficiency (SCID) is a congenital disorder leading to T-cell deficiency due to thymus development issues, which are hard to study in children due to the difficulty of obtaining thymic samples.
  • Researchers aimed to identify the specific stages of T-cell development that are halted in various SCID types by transplanting SCID bone marrow stem cells into a specialized mouse model and conducting extensive analyses.
  • The study found that certain mutations led to earlier-than-expected arrests in T-cell development, revealing crucial insights into the developmental blocks and their implications for understanding SCID.
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  • Thrombopoietin (Thpo) regulates blood cell production and stem cell maintenance through its receptor Mpl, and disruptions in this signaling can lead to blood disorders.
  • Researchers created a truncated version of Mpl (dnMpl) that doesn’t signal properly; when introduced into mice, it caused low platelet counts and a reduction in hematopoietic stem cells (HSC).
  • Analysis of HSC from these mice revealed increased cell cycle activity and similar gene expression changes found in human aplastic anemia, indicating that dnMpl affects stem cell behavior through specific gene regulation.
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Objective: Coeliac disease (CD), a gluten-induced enteropathy, alters the composition and function of duodenal intraepithelial T cells. The intestine also harbours four types of CD3-negative intraepithelial lymphocytes (IELs) with largely unknown function: CD56(-)CD127(-), CD56(-)CD127(+), CD56(+)CD127(-) and CD56(+)CD127(+). Here we aimed to gain insight into the potential function of these innate IELs in health and disease.

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High activation of the PI3K-AKT-mTOR pathway is characteristic for T-cell acute lymphoblastic leukemia (T-ALL). The activity of the master regulator of this pathway, PTEN, is often impaired in T-ALL. However, experimental evidence suggests that input from receptor tyrosine kinases (RTKs) is required for sustained mTOR activation, even in the absence of PTEN.

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Recent results indicate a significant contribution of innate immune signaling to maintain mucosal homeostasis, but the precise underlying signal transduction pathways are ill-defined. By comparative analysis of intestinal epithelial cells isolated from conventionally raised and germ-free mice, as well as animals deficient in the adaptor molecules MyD88 and TRIF, the TLR3 and TLR4, as well as the type I and III IFN receptors, we demonstrate significant TLR-mediated signaling under homeostatic conditions. Surprisingly, homeostatic expression of Reg3γ and Paneth cell enteric antimicrobial peptides critically relied on TRIF and, in part, TLR3 but was independent of IFN receptor signaling.

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Gene therapy for hematological disorders relies on the genetic modification of CD34(+) cells, a heterogeneous cell population containing about 0.01% long-term repopulating cells. Here, we show that the lentiviral vector CD133-LV, which uses a surface marker on human primitive hematopoietic stem cells (HSCs) as entry receptor, transfers genes preferentially into cells with high engraftment capability.

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Hematopoietic stem cells (HSCs) are defined by their ability to repopulate the bone marrow of myeloablative conditioned and/or (lethally) irradiated recipients. To study the repopulating potential of human HSCs, murine models have been developed that rely on the use of immunodeficient mice that allow engraftment of human cells. The NSG xenograft model has emerged as the current standard for this purpose allowing for engraftment and study of human T cells.

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Article Synopsis
  • * These mutations tend to cluster in areas that do not affect the overall fitness of the cells and show that most of her white blood cells come from just two related stem cell clones.
  • * Additionally, the shorter telomeres in her white blood cells compared to other tissues suggest that the aging process of hematopoietic stem cells, rather than harmful mutations, may drive changes in her blood cells at such an advanced age.
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Article Synopsis
  • Multipotent stromal cells (MSC) have immunomodulatory abilities and are being researched as a new type of therapy, particularly for their role in generating regulatory T cells (Tregs).
  • In laboratory studies, MSC derived from bone marrow were found to enhance the formation of Tregs in human immune cell populations, primarily through secreted factors, especially TGF-β1.
  • The presence of monocytes is crucial for this process, as MSC support their survival and drive their differentiation into macrophages that produce CCL18, which also contributes to Treg generation.
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Article Synopsis
  • * A combination of ligation-mediated PCR and pyrosequencing is used for detailed insertion profiling in various tissues, enabling cost-effective analysis of multiple DNA-barcoded samples.
  • * The study reveals significant variability in quantifying clonal abundance based on pyrosequencing, suggesting the need for careful calibration to accurately interpret results in polyclonal scenarios.
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  • Lentiviral (LV) vectors are being studied for their potential in treating hereditary diseases, particularly focusing on their use in liver gene therapy and assessing the associated risks of genotoxicity.* -
  • In a study with FAH((-/-)) mice, LV vectors were used to introduce the FAH gene, and researchers tracked the integration profile across multiple generations, finding that it remained polyclonal with minimal clonal expansion.* -
  • The results indicated that LV liver gene therapy did not lead to tumors and improved the lifespan of treated mice, suggesting a favorable risk profile for long-term gene expression and regeneration in liver cells.*
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The transcription factor Evi1 has an outstanding role in the formation and transformation of hematopoietic cells. Its activation by chromosomal rearrangement induces a myelodysplastic syndrome with progression to acute myeloid leukemia of poor prognosis. Similarly, retroviral insertion-mediated upregulation confers a competitive advantage to transplanted hematopoietic cells, triggering clonal dominance or even leukemia.

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