Mancini, V. | bioRxiv Science

bioRxiv2020

A new microfluidic concept for successful in vitro culture of mouse embryos

Innovative techniques for gene editing have enabled accurate animal models of human diseases to be established. In order for these methods to be successfully adopted in the scientific community, the optimization of procedures used for breeding genetically altered mice is required. Among these, the in vitro fertilization (IVF) procedure is still suboptimal and the culture methods do not guarantee the development of competent embryos. Critical aspects in traditional in vitro embryo culture protocols include the use of mineral oil and the stress induced by repetitive handling of the embryos. A new microfluidic system was designed to allow for efficient in vitro culture of mouse embryos. Harmful fluidic stress and plastic toxicity were excluded by completing the industry gold standard Mouse Embryo Assay. The potential competence of the embryos developed in the device was quantified in terms of blastocyst rate, outgrowth assay, energy substrate metabolism and expression of genes related to implantation potential. Mass spectrometry analyses identified plastic-related compounds released in medium, and confirmed leaching of low molecular weight species into the culture medium that might be associated to un-crosslinked PDMS. Finally, these data show the potential for the system to study preimplantation embryo development and to improve human IVF techniques.

bioengineering↗

bioRxiv2019

Polylactic acid, a sustainable, biocompatible, transparent substrate material for Organ-On-Chip and Microfluidic applications

Organ-on-chips are miniaturised devices aiming at replacing animal models for drug discovery, toxicology and studies of complex biological phenomena. The field of Organ-On-Chip has grown exponentially, and has led to the formation of companies providing commercial Organ-On-Chip devices. Yet, it may be surprising to learn that the majority of these commercial devices are made from Polydimethylsiloxane (PDMS), a silicone elastomer that is widely used in microfluidic prototyping, but which has been proven difficult to use in industrial settings and poses a number of challenges to experimentalists, including leaching of uncured oligomers and uncontrolled adsorption of small compounds. To alleviate these problems, we propose a new substrate for organ-on-chip devices: Polylactic Acid (PLA). PLA is a material derived from renewable resources, and compatible with high volume production technologies, such as microinjection moulding. PLA can be formed into sheets and prototyped into desired devices in the research lab. In this article we uncover the suitability of Polylactic acid as a substrate material for Microfluidic cell culture and Organ-on-a-chip applications. Surface properties, biocompatibility, small molecule adsorption and optical properties of PLA are investigated and compared with PDMS and other reference polymers.\n\nSignificanceOrgan-On-Chip (OOC) technology is a powerful and emerging tool that allows the culture of cells constituting an organ and enables scientists, researchers and clinicians to conduct more physiologically relevant experiments without using expensive animal models. Since the emergence of the first OOC devices 10 years ago, the translation from research to market has happened relatively fast. To date, at least 28 companies are proposing body and tissue on-a chip devices. The material of choice in most commercial organ-on-chip platforms is an elastomer, Polydymethyloxane (PDMS), commonly used in microfluidic R&D. PDMS is however subject to poor reproducibility, and absorbs small molecule compounds unless treated. In this study we show that PLA overcomes all the drawbacks related to PDMS: PLA can be prototyped in less than 45 minutes from design to test, is transparent, not autofluorescent, and biocompatible. PLA-based microfluidic platforms have the potential to transform the OOC industry as well as to provide a sustainable alternative for future Lab-On-Chip and point-of-care devices.

bioengineering↗