Search bioRxiv⌕ Search

Biology subjects

Lerouge, S.

Publications and source records attributed to Lerouge, S..

2 recordsLinked to original sources

Extended perfused culture of cm-scale endocrine pancreatic tissues created through sacrificial embedded printing into alginate

Pluripotent stem cells represent a potentially unlimited cell source for the fabrication of human bioartificial tissues to study and treat degenerative conditions such as type 1 diabetes. Alginate is widely used for mammalian cell immobilization and the primary hydrogel studied for pancreatic islet encapsulation. Rheological properties of alginate solutions or fully gelled forms are unsuitable as support matrix for embedded 3D printing. We describe partially gelled self-healing alginate formulations tuned for embedded 3D printing. Perfusable multi-plane hierarchical networks branching into 10 parallel channels, obtained by 3D printing of Pluronic F127 into the alginate support, show high fidelity to computer-assisted models. Therapeutic {beta}-cell doses (40x106 cells/mL) within centimeter-thick perfusable constructs remained viable for at least 1 week of culture under flow, with rapid insulin secretion detected upon glucose challenges. Stem cell-derived islet clusters cultured in 5-channel contructs for 25 days differentiated towards functional insulin-expressing cells. We describe a novel approach to generate cm-scale perfusable endocrine pancreatic constructs using sacrificial embedded 3D printing into alginate. This approach offers an adaptable platform to engineer perfusable cm-scale functional endocrine pancreatic tissues and potentially other vascularized bioartificial tissues.

bioengineering↗

Mesenchymal stromal cell encapsulation in uniform chitosan beads using microchannel emulsification

Mesenchymal stromal/stem cells hold potential in repairing damaged tissue through paracrine effects. Their delivery though injectable biodegradable microbeads can improve cell retention and survival at the infusion site. A stirred emulsion process was previously implemented to immobilize these cells in injectable chitosan microbeads for cell therapy applications, but this process leads to broad bead size distribution (coefficient of variation > 40 %). Polydisperse beads may negatively affect the viability of the entrapped cells through oxygen limitations, damage to larger beads during injection, and reduced control over the cell payload and treatment reproducibility. The objective of this work was to modify a microchannel emulsification system initially designed for alginate-based encapsulation to immobilize mesenchymal stromal/stem cells in monodisperse chitosan microbeads. The main factors (e.g., microchannel geometry, chitosan solution viscosity, interfacial tension and flow rate) affecting droplet generation and diameter were investigated. The adapted process enabled the production of monodisperse chitosan microbeads with controlled sizes ranging from 600 {micro}m - 1500 {micro}m in diameter at a coefficient of variation less than 10 %. In a single pass through a 21 G syringe needle (ID: 513 {micro}m), the fraction of ruptured beads was significantly reduced for microchannel-generated vs stirred emulsion-generated beads with matching volume-weighed bead diameter (D[4,3]). The viability of the immobilized cells immediately after the process was 95 % {+/-} 2 % and no significant difference in cell survival and growth factor secretion was observed between microchannel and stirred emulsion-generated beads over 3 days of culture. Future directions include channel multiplexing to increase throughput for clinical applications. Although the device was developed for cell encapsulation, this process could be implemented for encapsulation of other biomolecules, bioactive or living cell agents for applications in the food and drug industry.

bioengineering↗