Christophe Vieu

Blood filtration using micro-fabricated devices is an interdisciplinary topic of research and innovation driven by clinical applications in cytapheresis, cardiovascular disease monitoring, or liquid biopsy. In this paper, we demonstrate that a micro-perforated membrane can be equipped with sensing microelectrodes for detecting, in situ and in real-time, the capture of cellular material during ex vivo filtration of whole blood under high flow rates. This work describes the fabrication process of the sift and detection microdevice. We demonstrate that reliable electrical signals can be measured in whole blood samples flowing inside a fluidic system at typical flow rates, as large as 11.5 mL/min, hence allowing for large-volume sample processing. The in situ monitoring of the electrical impedance of the microelectrodes is shown to characterize the accumulation of living circulating cells retained by the filtrating membrane, opening interesting applications for monitoring blood filtration processes.

Compared to cell suspensions or monolayers, 3D cell aggregates provide cellular interactions organized in space and heterogeneity that better resume the real organization of native tissues. They represent powerful tools to narrow down the gap between in vitro and in vivo models, thanks to their self-evolving capabilities. Recent strategies have demonstrated their potential as building blocks to generate microtissues. Developing specific methodologies capable of organizing these cell aggregates into 3D architectures and environments has become essential to convert them into functional microtissues adapted for regenerative medicine or pharmaceutical screening purposes. Although the techniques for producing individual cell aggregates have been on the market for over a decade, the methodology for engineering functional tissues starting from them is still a young and quickly evolving field of research. In this review, we first present a panorama of emerging cell aggregates microfabrication and assembly technologies. We further discuss the perspectives opened in the establishment of functional tissues with a specific focus on controlled architecture and heterogeneity to favor cell differentiation and proliferation.

Since its emergence a few decades ago, nanotechnology has been shown to be a perfect example of a crossroad between different fundamentals sciences. In the last 10 years, the continuous progress of classical top-down lithography and the use of alternative bottom-up elaboration methods has allowed new and smaller components to be created. Their combination has led to very complex and innovative architectures. At the same time, flexible, low-cost, and low-ecological-footprint devices have emerged. Thus, the diversity and multidisciplinary features present challenges in addressing these issues in educational programs.

Growing multicellular spheroids recapitulate many features of expanding microtumours, and therefore they are an attractive system for biomechanical studies. Here, we report an original approach to measure and characterize the forces exerted by proliferating multicellular spheroids. As force sensors, we used high aspect ratio PDMS pillars arranged as a ring that supports a growing breast tumour cell spheroid. After optical imaging and determination of the force application zones, we combined 3D reconstruction of the shape of each deformed PDMS pillar with the finite element method to extract the forces responsible for the experimental observation. We found that the force exerted by growing spheroids ranges between 100nN and 300nN. Moreover, the exerted force was dependent on the pillar stiffness and increased over time with spheroid growth.

Plongé au cœur des nanos, Christophe Vieu souligne la diversité des secteurs touchés par l’approche nano. À l’idée d’une convergence des secteurs scientifiques, il oppose l’image d’une espèce invasive. Il se sent de ce fait investi d’une responsabilité de l’ensemble des technosciences.

Un dispositif d’éducation à la nanomédecine a été conçu suivant une logique inspirée de la didactique des questions socialement vives et mis en place en formation continue des enseignants avec comme visée principale la prise en compte des dimensions éthiques. Dans le cadre de cette expérimentation, les enseignants reçoivent une formation interdisciplinaire sur les aspects scientifiques, techniques et socio-éthiques liés au développement des nanotechnologies puis sont amenés à débattre entre eux autour d’une question relative au développement de la nanomédecine. L’analyse du corpus de débat permet de faire ressortir les points qui retiennent leur attention et le type de raisonnements moraux qu’ils mobilisent dans leur argumentation. L’analyse de cette expérimentation est discutée afin de réfléchir à des dispositifs didactiques sur des questions complexes de choix technologiques en rapport au vivant.

The adult brain is unable to regenerate itself sufficiently after large injuries. Therefore, hopes rely on therapies using neural stem cell or biomaterial transplantation to sustain brain reconstruction. The aim of the present study was to evaluate the improvement in sensorimotor recovery brought about by human primary adult neural stem cells (hNSCs) in combination with bio-implants. hNSCs were pre-seeded on implants micropatterned for neurite guidance and inserted intracerebrally 2 weeks after a primary motor cortex lesion in rats. Long-term behaviour was significantly improved after hNSC implants versus cell engraftment in the grip strength test. MRI and immunohistological studies were conducted to elucidate the underlying mechanisms of neuro-implant integration. hNSC implants promoted tissue reconstruction and limited hemispheric atrophy and glial scar expansion. After 3 months, grafted hNSCs were detected on implants and expressed mature neuronal markers (NeuN, MAP2, SMI312). They also migrated over a short distance to the reconstructed tissues and to the peri-lesional tissues, where 26% integrated as mature neurons. Newly formed host neural progenitors (nestin, DCX) colonized the implants, notably in the presence of hNSCs, and participated in tissue reconstruction. The microstructured bio-implants sustained the guided maturation of both grafted hNSCs and endogenous progenitors. These immunohistological results are coherent with and could explain the late improvement observed in sensorimotor recovery. These findings provide novel insights into the regenerative potential of primary adult hNSCs combined with microstructured implants.

E579 Background: Circulating tumor cells (CTCs) are cancer cells that have detached from a tumor and have entered into the blood circulation at a very low concentration (D. Shook, Mech. Dev., Nov 2003). CTCs have a strong prognostic value, as their number has been correlated to overall survival in different metastatic cancers (J. S. de Bono, Clin. Cancer Res., Oct 2008). Considering the rareness of CTCs in blood, capturing them in vitro is very challenging. CTCs being mainly larger and less deformable than most of blood cells, ISET was the first system exploiting their physical traits using a filtration membrane to enrich 10mL blood samples (G. Vona, Am. J. Pathol., Jan 2000). However, placing the trapping system directly within the bloodstream would increase the amount of blood screened and ensure no sampling bias. To our knowledge, the only system developed for in vivo capture of CTCs relies on an immunologic detection targeting CTCs with specific epithelial-cell adhesion molecules (N. Saucedo-Zeni, Int. J. Oncol., Oct 2012). The major drawback of this technique is the selection bias induced, given the strong heterogeneity of antigen expression profiles in CTC population as confirmed by several studies. Methods: Our device combines the advantages of in vivo capture and physical trapping of CTCs. A polymeric 3D net-like microdevice is fabricated using a Direct Laser Writing technique (Nanoscribe) and integrated onto a Nitinol guidewire to be introduced into the basilic vein through a routine 20G catheter. To optimize the design, we conducted simulation studies and in vitro assays using a fluidic platform reproducing in vivo conditions. Results: We succeeded in capturing PC3 human prostate cancer cells from 20 mL healthy donor blood spiked with 1,000 PC3 cells in 2 minutes, demonstrating the capability to capture CTCs in conditions close to those found in vivo, in terms of pressure and flow rate and without any additional treatment or dilution of the blood. Conclusions: This device could facilitate treatment personalization and follow-up. Its versatility should render it transposable to the capture of single or clustered CTCs, derived from all types of cancer and, by extension, to other circulating cellular and molecular biomarkers.