Embedded three-dimensional printing of thick pea-protein-enriched constructs for large, customized structured cell-based meat production.

Recent 3D-printing research showed the potential of using plant-protein-enriched inks to fabricate cultivated meat (CM) via agar-based support baths. However, for fabricating large, customized, structured, thick cellular constructs and further cultivation, improved 3D-printing capabilities and diffusion limit circumvention are warranted. The presented study harnesses advanced printing and thick tissue engineering concepts for such purpose. By improving bath composition and altering printing design and execution, large-scale, marbled, 0.5-cm-thick rib-eye shaped constructs were obtained. The constructs featured stable fibrous architectures comparable to those of structured-meat products. Customized multi-cellular constructs with distinct regions were produced as well. Furthermore, sustainable 1-cm-thick cellular constructs were carefully designed and produced, which successfully maintained cell viability and activity for 3 weeks, through the combined effects of void-incorporation and dynamic culturing. As large, geometrically complex construct fabrication suitable for long-term cellular cultivation was demonstrated, these findings hold great promise for advancing structured CM research.

3D model of mouse embryonic pancreas and endocrine compartment using stem cell-derived mesoderm and pancreatic progenitors.

The developing mouse pancreas is surrounded by mesoderm compartments providing signals that induce pancreas formation. Most pancreatic organoid protocols lack this mesoderm niche and only partially capture the pancreatic cell repertoire. This work aims to generate pancreatic aggregates by differentiating mouse embryonic stem cells (mESCs) into mesoderm progenitors (MPs) and pancreas progenitors (PPs), without using Matrigel. First, mESCs were differentiated into epiblast stem cells (EpiSCs) to enhance the PP differentiation rate. Next, PPs and MPs aggregated together giving rise to various pancreatic cell types, including endocrine, acinar, and ductal cells, and to endothelial cells. Single-cell RNA sequencing analysis revealed a larger endocrine population within the PP + MP aggregates, as compared to PPs alone or PPs in Matrigel aggregates. The PP + MP aggregate gene expression signatures and its endocrine population percentage closely resembled those of the endocrine population found in the mouse embryonic pancreas, which holds promise for studying pancreas development.

Ultrasound Mediated Polymerization for Cell Delivery, Drug Delivery, and 3D Printing.

Safe and accurate in situ delivery of biocompatible materials is a fundamental requirement for many biomedical applications. These include sustained and local drug release, implantation of acellular biocompatible scaffolds, and transplantation of cells and engineered tissues for functional restoration of damaged tissues and organs. The common practice today includes highly invasive operations with major risks of surgical complications including adjacent tissue damage, infections, and long healing periods. In this work, a novel non-invasive delivery method is presented for scaffold, cells, and drug delivery deep into the body to target inner tissues. This technology is based on acousto-sensitive materials which are polymerized by ultrasound induction through an external transducer in a rapid and local fashion without additional photoinitiators or precursors. The applicability of this technology is demonstrated for viable and functional cell delivery, for drug delivery with sustained release profiles, and for 3D printing. Moreover, the mechanical properties of the delivered scaffold can be tuned to the desired target tissue as well as controlling the drug release profile. This promising technology may shift the paradigm for local and non-invasive material delivery approach in many clinical applications as well as a new printing method - "acousto-printing" for 3D printing and in situ bioprinting.