Biology subjects

Brassard, J.

Publications and source records attributed to Brassard, J..

4 recordsLinked to original sources

bioRxiv2026

Bridging scale-up to transplantation: pluripotent stem cell-derived pancreatic islet encapsulation in emulsion-generated high concentration alginate beads

Pluripotent stem cell-derived pancreatic islet-like cell clusters (SC-islets) have emerged as potential cellular therapy for type 1 diabetes. While SC-islets can theoretically be produced in bioreactors to meet transplantation needs of many recipients per batch, biomanufacturing and translational challenges remain. SC-islet can be cultured in suspension using stirred tank or vertical wheel bioreactors, but these can impart hydrodynamic damage and lead to cellular agglomeration, particularly upon scale-up. We previously described a robust emulsion-based process to encapsulate murine pancreatic beta cells in high-concentration alginate beads which improved graft survival in allogeneic recipients. Here, we present a full pipeline for scalable microencapsulated SC-islet biomanufacturing with extended in vitro bioreactor culture leading into transplantation. We hypothesized that encapsulation would prevent cellular agglomeration, reduce mechanical stress, and preserve differentiation potential during scale-up. Encapsulation of Stage 6 SC-islets prevented cellular agglomeration during extended suspension culture (25 days) and increased cell recovery (91 +/- 3%) compared with non-encapsulated aggregates (60 +/- 10%). No significant differences in glucose-stimulated insulin secretion were observed with vs without microencapsulation. Stage 7 SC-islets matured in the bioreactor were transplanted either as encapsulated islets via the intraperitoneal route or as free SC-islets under the kidney capsule, where they displayed glucose-responsive human C-peptide secretion and remained functional in vivo for up to 98 days. Overall, this work establishes a scalable, robust, transplantation-ready encapsulation platform that supports SC-islet maturation and delivery, providing a generalizable strategy for scaling and transplanting encapsulated organoid systems.

bioengineering↗

bioRxiv2026

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↗

bioRxiv2024

An accessible platform to quantify oxygen diffusion in cell-laden hydrogels and its application to alginate-immobilized pancreatic beta cells

Hydrogels are commonly used to immobilize mammalian cells, serving various purposes such as providing mechanical cues in three-dimensional cultures and acting as barriers for immunoprotection in transplantation. For instance, islet encapsulation holds promise in delivering insulin-producing cells for diabetes cellular therapy. Cell immobilization, by creating a barrier to bulk fluid motion, leads to diffusion-limited molecular transport and concentration gradients of nutrients such as oxygen being consumed by the immobilized cells. Oxygen mass transport models aid in designing immobilization strategies but rely on input parameters like oxygen diffusivity, often assumed rather than experimentally measured due to limited resources or expertise. We propose an accessible, cost-effective, and easy to operate system to experimentally determine the diffusion coefficient of cell-laden hydrogels, with application tested to alginate-immobilized pancreatic beta cell (MIN6). As compared to water, the oxygen diffusion coefficient was significantly reduced in alginate gels. The oxygen diffusion coefficient was inversely correlated with the dynamic loss modulus for gels with similar chemical composition, and significantly reduced when the alginate concentration was increased from 2% to 5%. The viability of immobilized MIN6 cells was highly dependent both on gel concentration and cell density, as predicted by Thiele modulus and effectiveness factor values calculated from measured oxygen diffusion coefficients. The proposed platform, combining a simple experimental setup and the use of dimensionless numbers, offers a straightforward means to predict maximal diffusion distances in cell immobilization strategies. This platform can be implemented in the rational design of cell encapsulation, immobilized cell culture, and tissue engineering strategies.

bioengineering↗

bioRxiv2022

Mesenchymal Progenitors set the homeostatic inflammatory milieu via the TAK1-NFkB axis.

The ability of mesenchymal stromal cells to modulate inflammation is at the basis of the ongoing interest in their therapeutic potential. Yet, reliable success in clinical trials is limited, possibly due to a limited understanding of their impact on the inflammatory milieu in physiological conditions. Here we show that, at steady state, mesenchymal progenitors regulate the balance between type 1 and type 2 inflammatory milieus by acting on innate immune cells through the TAK1-NFkB pathway. Suppressing the constitutive activity of this pathway in MPs leads to skewing of the immune system toward systemic Type 2 inflammation (Th2). These changes have significant effects on diseases with an important inflammatory component, leading to a worsening of disease in a preclinical model of Th2-dependent Asthma, and a reduction of symptoms associated with Th1/Th17-dependent experimental autoimmune encephalitis.

cell biology↗