Prospective life cycle assessment of a bioprocess design for cultured meat production in hollow fiber bioreactors

The aim of cellular agriculture is to use cell-culturing technologies to produce alternatives to agricultural products. Cul-tured meat is an example of a cellular agriculture product, made by using tissue engineering methods. This study aims to improve the understanding of the potential environmental impacts of cultured meat production by comparing be-tween different bioprocess design scenarios. This was done by carrying out a life cycle assessment (LCA) for a bioprocess system using hollow fiber bioreactors, and utilizing bench-scale experimental data for C2C12 cell prolifer-ation, differentiation and media metabolism. Scenario and sensitivity analyses were used to test the impact of changes in the system design, data sources, and LCA methods on the results to support process design decision making. We com-pared alternative scenarios to a baseline of C2C12 cells cultured in hollow fiber bioreactors using media consisting of DMEM with serum, for a 16-day proliferation stage and 7-day differentiation stage. The baseline LCA used the average UK electricity mix as the energy source, and heat treatment for wastewater sterilization. The greatest reduction in en-vironmental impacts were achieved with the scenarios using CHO cell metabolism instead of C2C12 cell metabolisim (64-67 % reduction); achieving 128 % cell biomass increase during differentiation instead of no increase (42-56 % reduction); using wind electricity instead of average UK electricity (6-39 % reduction); and adjusting the amino acid use based on experimental data (16-27 % reduction). The use of chemical wastewater treatment instead of heat treatment increased all environmental impacts, except energy demand, by 1-16 %. This study provides valuable insights for the cultured meat field to understand the effects of different process design scenarios on environmental impacts, and therefore provides a framework for deciding where to focus development efforts for improving the envi-ronmental performance of the production system.Peer reviewe

Environmental impacts of cultured meat: alternative production scenarios

Cultured meat is produced by culturing animal muscle tissue in a laboratory without growing the whole animals. Its development is currently in a research stage. An earlier study showed that cultured meat production could potentially have substantially lower greenhouse gas emissions, land use and water use compared to conventionally produced meat. The aim of this paper is to amend the previous study by considering alternative production scenarios. The impacts of replacing cyanobacteria based nutrient media with plant based media are assessed. This paper includes more specific modelling of a bioreactor suitable for cultured meat production. Further, this study estimates the water footprint of cultured meat based on a method that is compliant with life cycle assessment. The environmental impacts of cultured meat are compared with conventionally produced meat and with plant based protein sources. It is concluded that regardless of the high uncertainty ranges cultured meat has potential to substantially reduce greenhouse gas emissions and land use when compared to conventionally produced meat.JRC.H.4-Monitoring Agricultural Resource

A Systematically Reduced Mathematical Model for Organoid Expansion

Organoids are three-dimensional multicellular tissue constructs. When cultured in vitro, they recapitulate the structure, heterogeneity, and function of their in vivo counterparts. As awareness of the multiple uses of organoids has grown, e.g. in drug discovery and personalised medicine, demand has increased for low-cost and efficient methods of producing them in a reproducible manner and at scale. Here we focus on a bioreactor technology for organoid production, which exploits fluid flow to enhance mass transport to and from the organoids. To ensure large numbers of organoids can be grown within the bioreactor in a reproducible manner, nutrient delivery to, and waste product removal from, the organoids must be carefully controlled. We develop a continuum mathematical model to investigate how mass transport within the bioreactor depends on the inlet flow rate and cell seeding density, focusing on the transport of two key metabolites: glucose and lactate. We exploit the thin geometry of the bioreactor to systematically simplify our model. This significantly reduces the computational cost of generating model solutions, and provides insight into the dominant mass transport mechanisms. We test the validity of the reduced models by comparison with simulations of the full model. We then exploit our reduced mathematical model to determine, for a given inlet flow rate and cell seeding density, the evolution of the spatial metabolite distributions throughout the bioreactor. To assess the bioreactor transport characteristics, we introduce metrics quantifying glucose conversion (the ratio between the total amounts of consumed and supplied glucose), the maximum lactate concentration, the proportion of the bioreactor with intolerable lactate concentrations, and the time when intolerable lactate concentrations are first experienced within the bioreactor. We determine the dependence of these metrics on organoid-line characteristics such as proliferation rate and rate of glucose consumption per cell. Finally, for a given organoid line, we determine how the distribution of metabolites and the associated metrics depend on the inlet flow rate. Insights from this study can be used to inform bioreactor operating conditions, ultimately improving the quality and number of bioreactor-expanded organoids

Hollow-fiber membrane technology: Characterization and proposed use as a potential mimic of skin vascularization towards the development of a novel skin absorption in vitro model

Dermal bioavailability is currently estimated through skin penetration studies using ex vivo models, which lack any measure of capillary bed function, and thus do not fully reproduce physiological conditions. We propose a novel strategy to mimic skin vascularization using newly fabricated hollow fibers made from a biocompatible membrane material, polystyrene, which is hydrophobic if left untreated, or hydrophilic when its surface polarity is modified through plasma-treatment. Caffeine has been well studied in skin penetration assays and was used here to determine the permeation properties of the hollow fibers in a novel jacketed glass bioreactor. For hydrophobic fibers, approximately 87.2 % of the caffeine dose did not penetrate the porous surface; 0.2 % of the dose was collected after 24 h (permeated through the pores), and therefore 12.6 % of the initial dose was suspected to block the membrane. For hydrophilic fibers, both the percentage of the initial dose that permeated and that of blocking caffeine increased to 1.2 % and 35.2 % respectively. It was concluded that caffeine permeated the hollow fibers at similar times of clearance to those observed in vivo, and therefore shows that this new model could provide a surrogate for capillary-based clearance in in vitro skin absorption studies

Surfactant-free poly(lactide-co-glycolide) honeycomb films for tissue engineering: relating solvent, monomer ratio and humidity to scaffold structure

International audienceOne-step surfactant-free, water-droplet templating has been developed as a fabrication method for a poly(lactide-co-glycolide) (PLGA) film that can be used as a model to investigate the relationship between solvent, monomer ratio, polymer concentration and humidity on its structure. The resulting material is a honeycomb-structured film. Formation of this structure was highly sensitive to solvent, monomer ratio, polymer concentration and humidity. Surfactant-free, water-droplet templating thus allows investigation of fabrication parameters and that PLGA monomer ratio selection is important for scaffold structure but not for MG63 cell attachment and proliferation

Mathematical modelling of fibre-enhanced perfusion inside\ud a tissue-engineering bioreactor

We develop a simple mathematical model for forced flow of culture medium through a porous scaffold in a tissue- engineering bioreactor. Porous-walled hollow fibres penetrate the scaffold and act as additional sources of culture medium. The model, based on Darcy’s law, is used to examine the nutrient and shear-stress distributions throughout the scaffold. We consider several configurations of fibres and inlet and outlet pipes. Compared with a numerical solution of the full Navier–Stokes equations within the complex scaffold geometry, the modelling approach is cheap, and does not require knowledge of the detailed microstructure of the particular scaffold being used. The potential of this approach is demonstrated through quantification of the effect the additional flow from the fibres has on the nutrient and shear-stress distribution