Biology subjects

Hoesli, C. A.

Publications and source records attributed to Hoesli, C. A..

5 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↗

bioRxiv2024

Iterative sacrificial 3D printing and polymer casting to create complex vascular grafts and multi-compartment bioartificial organs

Several emerging strategies to engineer artificial organs employ 3D printing to create vascular templates to provide nutrients and oxygen to immobilized cells. Significant challenges emerge when considering clinical implementation such as immune rejection of allogeneic cell sources, as well as achieving adequate perfusion and integration with endogenous vasculature. We propose a method by which cell-laden hydrogels are molded around ready-made polymeric vascular templates created via 3D printing to create human-scale artificial organs with internal vasculature. We applied this technique to create bioartificial pancreas systems with up to 9 internal flow channels via sacrificial carbohydrate glass 3D printing, porogen-loaded polycarbonate polyurethane dip-coating, followed by casting cell-laden hydrogels around the vascular templates. We optimized porogen size and concentration to maximise the porosity of our scaffolds without compromising mechanical properties, resulting in suture retention strength and compliance respectively matching commercial vascular grafts and native vessels. Bioreactor perfusion studies showed survival and maturation of stem cell derived pancreatic islets without significant differences to traditional suspension culture protocols. Insulin response dynamics were rapid in response to a glucose challenge at the perfusion inlet. Transplantation of the devices as iliac arteriovenous shunts in nondiabetic pigs confirmed safety and patency. These results show promise for the development of an implantable vascularized pancreas for the treatment of type 1 diabetes and demonstrate how bioartificial organs with engineered vascular geometries can be designed for translational applications.

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 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↗

bioRxiv2021

Bioaffinity-based Surface Immobilization of Antibodies to Capture Endothelial Colony-forming Cells

Maximizing the re-endothelialization of vascular implants such as prostheses or stents has the potential to significantly improve their long-term performance. Endothelial progenitor cell capture stents with surface-immobilized antibodies show significantly improved endothelialization in the clinic. However, most current antibody-based stent surface modification strategies rely on antibody adsorption or direct conjugation via amino or carboxyl groups which leads to poor control over antibody surface concentration and/or molecular orientation, and ultimately bioavailability for cell capture. Here, we assess the utility of a bioaffinity-based surface modification strategy consisting of a surface-conjugated cysteine-tagged protein G molecules that immobilize Immunoglobulin G (IgG) antibodies via the Fc domain to capture circulating endothelial colony-forming cells (ECFCs). The cysteine-tagged protein G was grafted onto aminated substrates at different concentrations as detected by an enzyme-linked immunosorbent assay and fluorescence imaging. Different IgG antibodies were successfully immobilized on the protein G-modified surfaces and higher antibody surface concentrations were achieved compared to passive adsorption methods. Surfaces with immobilized antibodies targeting endothelial surface proteins, such as CD144, significantly enhanced the capture of circulating ECFCs in vitro compared to surfaces with non-endothelial specific antibodies such as anti-CD14. This work presents a potential avenue for enhancing the clinical performance of vascular implants by using covalent grafting of protein G to immobilize IgG antibodies more effectively. Table of Contents O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=89 SRC="FIGDIR/small/449631v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@310b10org.highwire.dtl.DTLVardef@1cd8722org.highwire.dtl.DTLVardef@6306a0org.highwire.dtl.DTLVardef@1481eae_HPS_FORMAT_FIGEXP M_FIG C_FIG Antibody immobilization via surface-conjugated recombinant cysteine-protein G provides an effective approach to capture circulating therapeutic cells.

bioengineering↗