Speaker
Description
Title
Fabrication of Symbiotic Engineered Living Materials for Bone–Fat Interface Modelling
Introduction
The fabrication of in vitro tissues commonly involves the embedding of mesenchymal stem cells (MSCs) within a hydrogel matrix and the addition of biochemical or physical cues to passively instigate differentiation into a desired lineage. The PRISM-LT project adopts a proactive approach by introducing helper cells—genetically engineered yeast or bacteria—into the 3D construct. These microorganisms are designed to detect metabolic cues characteristic of MSC plasticity and respond by secreting lineage-specific stimulants. This synthetic symbiosis aims to facilitate localised, programmable differentiation, enabling the bioprinting of hybrid tissues composed of spatially compartmentalised voxels of bone, fat, and muscle. Two primary applications are envisioned: (1) the development of a bone/fat interface model for studying age-related bone marrow changes, and (2) the generation of structured cultured meat constructs.
Methods
To initiate the design of the system, helper cells were genetically engineered to constitutively express osteogenic and adipogenic factors using plasmid-based expression systems. In parallel, mesenchymal stem cells (MSCs) were encapsulated in gelatin methacrylate (GelMA) hydrogels of varying mechanical stiffness. Initial characterisation focused on optimising growth factor expression in microbial monocultures, as well as assessing the viability, morphology, and behaviour of MSCs within the hydrogel environment. Co-culture experiments in GelMA are planned as a next step to integrate both components under defined conditions.
Results
Engineered helper cells were successfully transformed with plasmids encoding osteogenic and adipogenic factors. Constitutive expression of growth factors in microbial monocultures was confirmed by SDS-PAGE and ELISA. Growth kinetics and viability assays indicated that both microbial systems remained stable under standard culture conditions. In parallel, MSCs encapsulated in GelMA hydrogels retained high viability over 21 days, with differences in cell morphology observed depending on hydrogel stiffness and density. The project has so far focused on the optimisation of individual components and will next aim to synergise them within a 3D construct.
Discussion
These early findings provide proof-of-concept for the feasibility of symbiotic tissue constructs containing MSCs and programmable microbial partners. The capacity of helper cells to survive in a hydrogel and secrete bioactive proteins presents an opportunity for on-demand, localised MSC stimulation. Challenges remain in regulating microbial growth kinetics. Future efforts will focus on spatially resolved bioprinting, multi-lineage differentiation, and the integration of feedback-controlled genetic circuits. Ultimately, this platform holds potential for constructing complex tissue interfaces for both biomedical and food engineering applications.
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