The role of osmolarity adjusting agents in the regulation of encapsulated cell behavior to provide a safer and more predictable delivery of therapeutics

Abstract

Transplantation of cells within alginate microspheres has been extensively studied for sustained drug delivery. However, the lack of control over cell behavior represents a major concern regarding the efficacy and the safety of the therapy. Here, we demonstrated that when formulating the biosystem, an adequate selection of osmolarity adjusting agents significantly contributes to the regulation of cell responses. Our data showed that these agents interact in the capsule formation process, influencing the alginate crosslinking degree. Therefore, when selecting inert or electrolyte-based osmolarity adjusting agents to encapsulate D1 multipotent mesenchymal stromal cells (MSCs), alginate microcapsules with differing mechanical properties were obtained. Since mechanical forces acting on cells influence their behavior, contrasting cell responses were observed both, in vitro and in vivo. When employing mannitol as an inert osmolarity adjusting agent, microcapsules presented a more permissive matrix, allowing a tumoral-like behavior. This resulted in the formation of enormous cell-aggregates that presented necrotic cores and protruding peripheral cells, rendering the therapy unpredictable, dysfunctional, and unsafe. Conversely, the use of electrolyte osmolarity adjusting agents, including calcium or sodium, provided the capsule with a suitable crosslinking degree that established a tight control over cell proliferation and enabled an adequate therapeutic regimen in vivo. The crucial impact of these agents was confirmed when gene expression studies reported pivotal divergences not only in proliferative pathways, but also in genes involved in survival, migration, and differentiation. Altogether, our results prove osmolarity adjusting agents as an effective tool to regulate cell behavior and obtain safer and more predictable therapies.ARTICLE HISTORY

Relaxation of Extracellular Matrix Forces Directs Crypt Formation and Architecture in Intestinal Organoids

“…It is possible that at these higher weight percent formulations, an increase in hydrogel swelling (upon equilibration) applies a swelling force to the encapsulated colonies, decreasing their survival . In this case, decreased survival could also be attributed to osmotic effects . While Matrigel might seem to contradict these hypotheses as it is a very soft material, Matrigel and other protein materials have been shown to exhibit strain stiffening behavior, meaning organoids would experience higher local forces …”

3D cell-laden polymers to release bioactive products in the eye

“…Tailoring of the physicochemical properties of the developed system for the target cell type is important for its compatibility and functionality. which at the same time provides a safer and more predictable delivery of peptides/proteins (Gonzalez-Pujana et al, 2017a) Finally, biosafety represents, undoubtedly, a paramount concern for this biotechnological approach in its path towards clinical use (Santos et al, 2013b).…”

Advances in the slow freezing cryopreservation of microencapsulated cells

“…Moreover, this cell type can immune-modulate the environment, avoiding the immune system reaction, which is desirable for cellular implants [111,112]. Their encapsulation in hydrogels or alginate capsules has been studied extensively [84,[113][114][115], and their storage also investigated in the last few years ( Table 4).…”

“…Thus, the efforts to cryopreserve cell-based products made of natural polymers (e.g., agarose, hyaluronic acid, fibrin or collagen) or synthetic polymers (e.g., PEG) have linearly grown with its reflection in more publications in last decades[22,30,47,79,81]. Alginate has been one of the most often used polysaccharides to form cellularized bioscaffolds due to its potential as sustained drug delivery or cell delivery systems for the treatment of different diseases (e.g., diabetes, hepatic diseases, neurodegenerative or cancer among others)[82][83][84][85]. Cells are embedded in the biocompatible matrix of alginate, and sometimes covered by a semipermeable membrane, such as poly-L-lysine.…”