Biology subjects

Moisan, A.

Publications and source records attributed to Moisan, A..

5 recordsLinked to original sources

bioRxiv2025

Tissue engineered endothelial keratoplasty with controlled endothelial cell density: proof of concept and paving the way for super TEEKs

Over the past 20 years, endothelial keratoplasty procedures have revolutionized the treatment of corneal endothelial disorders. These conditions have now become the leading indication for corneal transplantation in Western countries and account for half of all donor cornea usage. Despite their undeniable success, the global shortage of donor tissues and major disparities between nations justify the development of alternatives to donor grafts. Cell therapy using injections of suspended endothelial cells has proven effective, and tissue-engineered endothelial keratoplasty (TEEK) comprising a membrane coated with cultured endothelial cells is under development to better mimic the native endothelial graft. Our team utilizes a femtosecond-laser-cut lens capsule disc as a bioengineering scaffold, taking advantage of this novel tissues biocompatibility, transparency, curvature, and availability. In the present study, we provide proof of concept, in 12 TEEKs, that it is possible to control the final endothelial cell density (ECD) by varying the seeding density per mm2. Cell characterization was performed through morphometric analysis of the endothelial mosaic stained with anti-NCAM (a lateral membrane marker used as a differentiation marker), using the CellPose artificial intelligence algorithm specifically trained for in vitro endothelium segmentation. Five criteria related to pleomorphism, polymorphism, and elongation were combined into a single endothelial quality score. The median cell viability at 28 days of culture, assessed by Hoechst 33342 and Calcein-AM staining, reached 98% (range: 83-99%). The median viable ECD (number of live cells per surface unit) in the highest-density group was 3,245 cells/mm2 (range: 2,778-3,753), paving the way for the bioengineering of supra-physiological TEEKs, or super TEEKs. Impact statementThe process of manufacturing tissue-engineered endothelial keratoplasty (TEEK) allows for the control of endothelial cell density (DCE) and, in particular, the creation of super TEEKs, meaning grafts with supra-physiological DCE that are more likely to better withstand the challenges of surgery and have a prolonged lifespan in recipients.

bioengineering↗

bioRxiv2024

Tissue determinants of the human T cell receptor repertoire.

98% of T cells reside in tissues, yet nearly all human T cell analyses are performed from peripheral blood. We single-cell sequenced 5.7 million T cells from ten donors autologous blood and tonsils and sought to answer key questions about T cell receptor biology previously unanswerable by smaller-scale experiments. We identified distinct clonal expansions and distributions in blood compared to tonsils, with surprisingly low (1-7%) clonal sharing. These few shared clones exhibited divergent phenotypes across bodily sites. Analysis of antigen-specific CD8 T cells revealed location as a main determinant of frequency, phenotype, and immunodominance. Finally, diversity estimates from the tissue recalibrates current repertoire diversity estimates, and we provide a refined estimate of whole-body repertoire. Given the tissue-restricted nature of T cell phenotypes, functions, differentiation, and clonality revealed by this dataset, we conclude that tissue analyses are crucial for accurate repertoire analysis and monitoring changes after perturbing therapies.

immunology↗

bioRxiv2023

A novel injectable radiopaque hydrogel with potent properties for multicolor CT imaging in the context of brain and cartilage regenerative therapy

Cell therapy is promising to treat many conditions, including neurological and osteoarticular diseases. Encapsulation of cells within hydrogels facilitates cell delivery and can improve therapeutic effects. However, much work remains to be done to align treatment strategies with specific diseases. The development of imaging tools that enable monitoring cells and hydrogel independently is key to achieving this goal. Our objective herein is to longitudinally study an iodine-labeled hydrogel, incorporating gold-labeled stem cells, by bicolor CT imaging after in vivo injection in rodent brains or knees. To this aim, an injectable self-healing hyaluronic acid (HA) hydrogel with long-persistent radiopacity was formed by the covalent grafting of a clinical contrast agent on HA. The labeling conditions were tuned to achieve sufficient X-ray signal and to maintain the mechanical and self-healing properties as well as injectability of the original HA scaffold. The efficient delivery of both cells and hydrogel at the targeted sites was demonstrated by synchrotron K-edge subtraction-CT. The iodine labeling enabled to monitor the hydrogel biodistribution in vivo up to 3 days post-administration, which represents a technological first in the field of molecular CT imaging agents. This tool may foster the translation of combined cell-hydrogel therapies into the clinics.

bioengineering↗

bioRxiv2022

In vitro replicative potential of an HIV-1/MO intergroup recombinant virus compared to HIV-1/M and HIV-1/O parental viruses

HIV-1 is characterized by high genetic diversity and genetic recombination is one of the major evolution processes. Despite their great genetic divergence, HIV-1 group M, pandemic, and group O, endemic in Cameroon, can generate HIV-1/MO intergroup recombinants. The current description of 19 HIV-1/MO recombinant forms (URF_MO) raises the question of a possible benefit of the recombination and the modalities of their emergence. Therefore, the objectives of this work were to study in vitro the replicative potential of HIV-1/MO recombinant forms. The replicative potential was analyzed, based on a simple recombination pattern, [Ogag/pol-Menv], harboring a breakpoint in Vpr, due to a recombination hotspot in this region. For this, a chimeric infectious molecular clone (IMC) was synthesized from HIV-1/M subtype B and HIV-1/O subgroup T and recombinant viruses were obtained by transfection and co-culture. To compare the replicative potential of recombinant viruses with HIV-1/M and HIV-1/O parental viruses, two markers were monitored in culture supernatants: Reverse Transcriptase (RT) activity and P24 antigen concentration. The results showed a superiority of the group M parental virus compared to group O for both markers. In contrast, for the HIV-1/OM recombinant virus, RT activity data did not overlap with the concentration of P24 antigen, suggesting a hybrid behavior of the recombinant, in terms of enzyme activity and P24 production. These results highlighted many hypotheses about the impact of recombination on replicative potential and demonstrated once again the significant plasticity of HIV genomes and their infinite possibility of evolution. ImportanceHIV-1/M and HIV-1/O can generate HIV-1/MO intergroup recombinants. The current description of 19 URF_MO raises the question of a possible benefit of recombination in terms of emergence. The objectives of this work were to study in vitro the replicative potential of HIV-1/MO recombinant viruses. For this, a chimeric infectious molecular clone (IMC) generated from HIV-1/M subtype B and HIV-1/O subgroup T and recombinant viruses were obtained by transfection and co-culture. To compare the replicative potential of recombinant viruses with HIV-1/M and HIV-1/O parental viruses, RT activity and P24 antigen concentration were monitored in culture supernatants. A superiority of the group M parental virus compared to group O was observed for both markers whereas a hybrid behavior in terms of enzyme activity and P24 production was found for the recombinant virus. These results demonstrated once again the significant plasticity of HIV genomes and their infinite possibility of evolution.

microbiology↗

bioRxiv2021

Human immunocompetent Organs-on-Chips platforms allow safety profiling of tumor-targeted T-cell bispecific antibodies

AbstractTraditional drug safety assessment often fails to predict complications in humans, especially when the drug targets the immune system. Here, we show the unprecedented capability of two Organs-on-Chips to evaluate the safety profile of T-cell bispecific antibodies (TCBs) targeting tumor antigens. Although promising for cancer immunotherapy, TCBs are associated with an on-target, off-tumor risk due to low levels of expression of tumor antigens in healthy tissues. We leveraged in vivo target expression and toxicity data of TCBs targeting folate receptor 1 (FOLR1) or carcinoembryonic antigen (CEA) to design and validate human immunocompetent Organs-on-Chips safety platforms. We discovered that the Lung-Chip and Intestine-Chip could reproduce and predict target-dependent TCB safety liabilities, based on sensitivity to key determinants thereof, such as target expression and antibody affinity. These novel tools broaden the research options available for mechanistic understandings of engineered therapeutic antibodies and assessing safety in tissues susceptible to adverse events.

cancer biology↗