Viande cultivée | EPFL Graph Search

thumb|300px|La scientifique autrichienne goûte le premier hamburger cultivé au monde le . vignette|Cuisson du premier steak cultivé. La viande cultivée, aussi appelée viande de culture, est un produit carné réalisé par des techniques d'ingénierie tissulaire qui évitent ainsi l'abattage d'animaux. Elle est produite à partir de cellules animales que l'on fait croître en dehors du corps de l'animal, « dans des cuves similaires à celles utilisées pour la fermentation traditionnelle de la bière et du yaourt ». La viande cultivée est produite selon la technique de la culture cellulaire (ou « agriculture cellulaire »), déjà utilisée en médecine régénérative. Un des objectifs mis en avant par ses partisans est la réduction de l'impact environnemental de l'élevage. La viande est un ensemble de muscles comprenant des tendons et de la graisse plus du tissu organique non-élastique, et composée de cellules. La production de « viande cultivée » se fait directement à l’échelle des cellules. Après un prélèvement indolore par biopsie de cellules souches, celles-ci se multiplient et se différencient en cellules de muscles dans un environnement adapté à leur croissance. Ces cellules de muscles peuvent être ajoutées à des cellules de graisse et de tissus conjonctifs pour former de la viande. La viande cultivée devrait avoir idéalement la même composition que la viande conventionnelle, en reproduisant le processus naturel biologique qui se déroule dans l'organisme des animaux. « Rien ne différencie moléculairement la viande conventionnelle de la viande cultivée » selon . Plusieurs possibilités existent pour l'obtention des cellules: une biopsie est effectuée (sous anesthésie locale), une utilisation de cellules souches est faite à partir d'une banque de cellules souches. Plusieurs projets de recherche actuels développent de la viande cultivée à partir de cellules souches de myoblastes. En 1912, le biologiste français Alexis Carrel maintient en vie un morceau de muscle cardiaque de poussin dans une boîte de Pétri, démontrant la possibilité de maintenir le tissu musculaire vivant à l'extérieur du corps.

Microtissue models for studying the dynamics of host-pathogen interactions in the urinary bladder

Kunal Sharma

Urinary tract infections (UTIs) are amongst the most common bacterial infections and are the second-most frequent reason for antibiotic prescriptions. Moreover, in about 25% of all treated cases, recurrence of infection occurs. Uropathogenic Escherichia coli (UPEC) is the most common causative agent of UTIs. Much of our current understanding about UTIs has come from mouse models of UTI which have highlighted the intracellular lifestyle of this pathogen in the forms of intracellular bacterial communities (IBCs) as the prominent cause for bacterial persistence. Recurrent infections are thought to be caused by bacterial fluxing from persistent IBCs in the umbrella cell layer of the epithelia in the bladder. Although in vitro model systems of UTIs have been developed to study acute phases of infection including the formation of IBC and their dispersal, they suffer from certain shortcomings. For example, these models lack vasculature and the possibility to impose mechanical stresses, such as those experienced by the cells during bladder filling and voiding. Moreover, the design of these in vitro systems makes it difficult to study long-term UPEC persistence when exposed to antibiotic or neutrophil-mediated stresses. In the last two decades, two bioengineering approaches have emerged to generate functional and physiological tissues: organoid and organ-chip systems. Differentiating cells self-organize in a hydrogel and enable the formation of organoids, which mimic various aspects of organ physiology and function in a three-dimensional structure. Organ-chip systems rely upon co-culturing pre-differentiated cells across a synthetic membrane in a defined geometry. The organ-chip systems allow dynamic control over environmental (nutritive) state and over the mechanical stresses experienced by the emulated tissue. In this thesis, I showcase the development of model systems to study UPEC pathogenesis using both these approaches. In the first part of this thesis, we developed a bladder organoid model of UPEC infection that recapitulates the stratified bladder architecture within a volume suitable for high-resolution live-cell imaging. Bacteria injected into the organoid lumen rapidly enter umbrella cells and proliferate to form IBCs. Unexpectedly, we identified populations of individual âsolitaryâ bacteria that form independently of IBCs and which penetrate deeper layers of the organoid wall, and evade killing by antibiotics and neutrophils. Volumetric electron microscopy revealed that these solitary bacteria may be intracellular or pericellular (sandwiched between uroepithelial cells) and are rod-shaped and flagellated, unlike coccoid-shaped and unflagellated bacteria within IBCs. Bacterial fluxing from IBCs is therefore not an essential requirement for the establishment of persistent bacterial populations in the bladder wall. The dynamic responses of IBCs to host stresses and antibiotic therapy are difficult to assess in situ. In another study, we focussed on examining the lifecycle and persistence of IBCs during early stages of UTIs. We developed a human bladder-chip model wherein superficial umbrella cells and bladder microvascular endothelial cells are co-cultured under flow in urine and nutritive media respectively. Bladder filling and voiding was mimicked mechanically by application and release of linear strain. Using time-lapse microscopy, we show that rapid recruitment of neutrophils from the vascular channel

EPFL2021

Bioengineering Methods to Improve in vitro Adoptive Cell Therapy based on Tumor-Infiltrating Lymphocytes

François Réal Rivest

Cancer is one of the biggest medical challenges of our times, with a devastating impact across all social categories. Accordingly, considerable efforts are geared towards improving the standard of care. Among them, immunotherapy, which relies on the immune system's capacity to fight cancer cells, brings new hope for higher success rates and in some cases even a cure of this devastating disease. A particularly interesting approach called adoptive cell therapy, or ACT, is based on immune cells that have infiltrated tumors and have the potential to fight them. Unfortunately, these tumor-infiltrating lymphocytes (TILs) are very rare and their activity is often suppressed by components of the tumor microenvironment (TME). However, TILs can be extracted from tumor biopsies, reactivated and expanded in vitro before being reinjected into the patient. This immunotherapy strategy has shown impressive results in melanoma, where a majority of patients have seen a complete tumor remission. However, for most solid cancers (e.g. lung or colorectal cancer) that are in general less prone to mount immune responses, this approach is less effective. Other reasons for the currently limited success rate of ACT include the ineffectiveness to expand TILs in vitro, as well as the lack of functional assays to probe their potency after culture. Indeed, existing tumor models are based either on the non-physiological culture of cancer cell lines on plastic dishes or on the implantation of a patient's tumor tissue into an immune-deficient mouse, an assay that is highly complex, inefficient and expensive. Recent breakthroughs in 3D primary cell culture technology have provided paths forward in overcoming these challenges. In particular, the derivation of patient-derived miniaturized tumors, or tumoroids, has enabled the recapitulation of some key functional characteristics of real tumors. When co-cultured with fibroblasts or immune cells, tumoroids are potentially powerful models for immunotherapy applications. However, despite promising proof-of-concept demonstrations of modeling the TME with such heterotypic tumoroids, it has neither been possible to derive such complex in vitro tumor models with all key cell types isolated from the same patient's tumor, nor to maintain the numbers and phenotypes of TME-derived cells in longer-term cultures. Moreover, existing tumoroids are highly heterogeneous and unsuitable for the development of scalable and reproducible assays that are needed in diagnostic applications. This thesis focused on the bioengineering of novel in vitro tools to address some of the aforementioned obstacles in realizing the promise of TIL therapy. First, to generate heterotypic and autologous tumoroids, existing protocols were optimized to isolate and expand cancer cells, fibroblasts, and TILs from colorectal cancer (CRC) samples. A small biobank was established for each cell type as a resource for the development and application of patient-specific tumoroid assays. In the second part of this thesis, a heterotypic CRC tumoroid platform was developed for testing autologous TIL potency in combination with immunotherapeutic agents. CRC tumoroids were derived in high-throughput on a hydrogel substrate comprising an array of regularly spaced, round-bottom microcavities, a set-up that was found to highly amenable to quantitative experimentation. ... More in the full text ...

EPFL2020