Biology subjects

Hoesli, C. A.

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

2 recordsLinked to original sources

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↗