Alginate micro-encapsulation of mesenchymal stromal cells enhances modulation of the neuro-inflammatory response

Abstract

Background aims Modulation of inflammation after brain trauma is a key therapeutic goal aimed at limiting the consequences of the subsequent injury cascade. Mesenchymal stromal cells (MSCs) have been demonstrated to dynamically regulate the inflammatory environment in several tissue systems, including the central nervous system. There has been limited success, however, with the use of direct implantation of cells in the brain caused by low viability and engraftment at the injury site. To circumvent this, we encapsulated MSCs in alginate microspheres and evaluated the ability of these encapsulated MSCs to attenuate inflammation in rat organotypic hippocampal slice cultures (OHSC). Methods OHSC were administered lipo-polysaccharide to induce inflammation and immediately co-cultured with encapsulated or monolayer human MSCs. After 24 h, culture media was assayed for the pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-α) produced by OHSC, as well as MSC-produced trophic mediators. Results Encapsulated MSCs reduced TNF-α more effectively than did monolayer MSCs. Additionally, there was a strong correlation between increased prostaglandin E2 (PGE2) and reduction of TNF-α. In contrast to monolayer MSCs, inflammatory signals were not required to stimulate PGE2 production by encapsulated MSCs. Further encapsulation-stimulated changes were revealed in a multiplex panel analyzing 27 MSC-produced cytokines and growth factors, from which additional mediators with strong correlations to TNF-α levels were identified. Conclusions These results suggest that alginate encapsulation of MSCs may not only provide an improved delivery vehicle for transplantation but may also enhance MSC therapeutic benefit for treating neuro-inflammation.

Development and validation of a microfluidic immunoassay capable of multiplexing parallel samples in microliter volumes

“…The decrease in TNF-α secretion observed from the hippocampal slice in the presence of MSC is consistent with our studies using conventional techniques 18 . While the biological effects of eMSC on hippocampal slices are discussed in detail in that report, the differences in the cytokines measured here demonstrates the ability of this device to be used as a screening tool in in vitro systems.…”

“…In addition, we test and demonstrate the accuracy of the device over a large dynamic range with sensitivity comparable to the standard bench-top assay. Finally, we measure supernatants generated with our established co-culture model of lipopolysaccharide (LPS) treated rat hippocampal slices 18 . LPS treatment of hippocampal slices induces a cytokine response, while co-culture with alginate encapsulated human mesenchymal stem cells (eMSC) provides immunomodulation.…”

Generation and manipulation of hydrogel microcapsules by droplet-based microfluidics for mammalian cell culture

“…In addition, co-encapsulation and co-culture of MBA2 and umbilical cord blood (UCB) cells were also performed by the same system, and differential responsiveness of UCB subpopulations to paracrine signals from MBA2 were revealed 216 . Of note, the immunomodulatory effects of MSC on inflammation was also demonstrated by co-culturing hydrogel encapsulated MSC and macrophage or organotypic hippocampal slice cultures 37, 64, 159 , though those encapsulations were not performed by droplet-based microfluidics due to its relatively low throughput compared to electrospray.…”

“…Electrospraying, which takes advantage of electric fields and Rayleigh-Plateau instability, is conventionally used to generate cell-laden microdroplets and hydrogel microcapsules 37, 38 . Nevertheless, microcapsules produced by this method have high size polydispersity due to the unstable breakup in jetting mode and irregular morphologies due to the entry impact of microcapsules into the solution of crosslinking agents 39–42 .…”

The Challenge of Human Mesenchymal Stromal Cell Expansion: Current and Prospective Answers

“…A semi-permeable membrane allows the diffusion of molecules (e.g., nutrients and therapeutic proteins) but protects the cells from the host immune system and mechanical forces, thus potentially enhancing the therapeutic benefits of hMSCs [118]. Various production methods have been tested to generate small beads (200-400 µm) with a narrow size distribution [119].…”