Biology subjects

Gillis, C. J.

Publications and source records attributed to Gillis, C. J..

3 recordsLinked to original sources

bioRxiv2026

Development of a rocking bioreactor strategy to augment pro-angiogenic factor secretion by human adipose-derived stromal cells

Cell therapies involving human adipose-derived stromal cells (hASCs) have shown promise for a range of clinical applications due to their ability to stimulate angiogenesis and dampen inflammation via paracrine mechanisms. However, a major barrier to the successful clinical translation of hASC-based therapies is that standard culture methods for expansion on rigid 2D tissue-culture polystyrene under static conditions diminish the pro-regenerative functionality of the cells. To address these limitations, the current project focused on the development of an in vitro bioreactor system for preconditioning hASCs to augment their capacity to stimulate regeneration through paracrine mechanisms. Specifically, the combined effects of decellularized adipose tissue (DAT) coatings, shear-stress stimulation, and varying oxygen tensions on hASC expansion and paracrine factor secretion were assessed. Additional studies were performed to characterize the effects of stimulating hASCs within the rocking bioreactor system using the pro-inflammatory cytokines IFN-{gamma} and TNF-. Expansion in the bioreactor under all conditions supported hASC growth with no observable morphological differences. However, dynamic culture on DAT coatings enhanced intracellular indoleamine 2,3-dioxygenase (IDO) expression in hASCs cultured under 20% O2. Moreover, culturing under dynamic conditions and/or on DAT coatings significantly increased secretion of the pro-angiogenic factors VEGF, HGF, and angiogenin. When pro-inflammatory cytokine priming was introduced, the expression of all tested paracrine factors was enhanced, particularly the immunomodulatory factors IL-6, IL-8 and MCP-1. Overall, a novel bioreactor system was developed for hASC expansion and preconditioning, demonstrating that the cell microenvironment can be tuned to modulate hASC paracrine factor secretion.

bioengineering↗

bioRxiv2025

Co delivery of human adipose derived stromal cells and endothelial colony forming cells in cell-assembled decellularized adipose tissue scaffolds for applications in soft tissue regeneration

Cellular therapies involving the co-delivery of cells with complementary pro-regenerative functionality hold promise as a strategy to promote soft tissue regeneration. In particular, the co-delivery of adipose-derived stromal cells (ASCs) and endothelial colony-forming cells (ECFCs) has shown promise for regenerating stable blood vessels in vivo. The current study developed novel "cell-assembled" scaffolds for co-delivering human ASCs and ECFCs within a supportive decellularized adipose tissue (DAT) matrix, with the objective of enhancing their localized retention and augmenting their capacity to stimulate adipose tissue regeneration. Human ASCs and ECFCs were seeded separately onto human-derived DAT microcarriers under cell-type specific conditions. The cell-seeded microcarriers were then combined and cultured for 8 days under conditions that promoted matrix remodeling to fuse the microcarriers into 3D engineered tissues containing ASCs+ECFCs, ASCs alone, or ECFCs alone. Co-culture with ECFCs within the scaffolds was shown to modulate ASC pro-angiogenic gene expression, with some ECFCs forming tubule-like structures in vitro in both the ASC+ECFC and ECFC alone groups. In vivo bioluminescence imaging using a dual luciferase reporter system showed that co-delivery with ASCs enhanced ECFC retention following subcutaneous implantation in athymic nu/nu mice, but co-delivery did not alter the localized retention of viable ASCs. Interestingly, while immunofluorescence staining for CD31 and microcomputed tomography angiography indicated that vascular regeneration was similar in the cell-assembled scaffolds containing ASC+ECFCs, ASCs alone, and ECFCs alone, histological staining revealed that extensive regions of the ECFC alone scaffolds had remodelled into adipose tissue at 29 days post-implantation.

bioengineering↗

bioRxiv2024

A simple, cost-effective microfluidic device using a 3D cross-flow T-junction for producing decellularized extracellular matrix-derived microcarriers

Cell therapies using human mesenchymal stromal cells (MSCs) are promising for a wide variety of clinical applications. However, broad-scale clinical translation is limited by conventional culture methods for MSC expansion within 2D tissue-culture flasks. MSC expansion on ECM-derived microcarriers within stirred bioreactor systems offers a promising approach to support MSC growth. Previously, our team established methods for fabricating ECM-derived microcarriers from a variety of decellularized tissue sources using electrospraying techniques. However, these microcarriers are relatively large and have a broad size distribution, which may limit their utility. Smaller and more uniform microcarriers may be favorable for MSC growth within bioreactors and have greater potential to serve as a minimally invasive injectable cell delivery platform. To address these limitations, the current project focused on the development of a new microfluidic-based approach enabling both uniform and small microcarrier production. Using a novel, modified 3D T-junction design, we successfully generated microcarriers using human decellularized adipose tissue (DAT) as the ECM source. Our new cost-effective device produced microbeads that were small and monodisperse, at a range of flow rate combinations and with high production rates. Photo-crosslinking using rose bengal allowed for the generation of microcarriers that were stable following rehydration, with a mean diameter of 196 {+/-} 47 {micro}m. Following methods optimization and microcarrier characterization, in vitro studies confirmed that the new microcarriers supported human adipose-derived stromal cell (hASC) attachment and growth, as well as ECM production, across 14 days within spinner flask bioreactors. Overall, this study demonstrates the feasibility of using our novel, cost-effective, and reusable microfluidics device to generate cell-supportive microcarriers comprised exclusively of ECM in a size range that could be injected via a small gauge needle and were stable in long-term culture.

bioengineering↗