Hydrogels used for cell‐based drug delivery

Abstract

Stem cells, progenitor cells, and lineage-committed cells are being considered as a new generation of drug depots for the sustained release of therapeutic biomolecules. Hydrogels are often used in conjunction with the therapeutic secreting cells to provide a physical barrier to protect the cells from hostile extrinsic factors. Although the hydrogels significantly improve the therapeutic efficacy of transplanted cells, there have been no successful products commercialized based on these technologies. Recently, biomaterials are increasingly designed to provide cells with both a physical barrier and an extracellular matrix to further improve the secretion of therapeutic proteins from cells. This review will discuss (1) the cell encapsulation process, (2) the immunogenicity of the encapsulating hydrogel, (3) the transport properties of the hydrogel, (4) the hydrogel mechanical properties, and will propose new strategies to improve the hydrogel and cell interaction for successful cell-based drug delivery strategies.

Functional improvement of porcine neonatal pancreatic cell clustersviaconformal encapsulation using an air-driven encapsulator

“…There was no penetration by 150 kDa dextrans, whereas the 20 and 70 kDa dextrans easily penetrated the small capsules. Indeed, the penetration of materials inside the capsule was not dependent on the thickness of the alginate capsule but rather on the pore size of the semi-permeable capsule, which can be controlled by the initial alginate solution concentration and alginate molecular weight (Schmidt et al, 2008). We confirmed that the small capsules produced by an air-driven encapsulator could effectively protect islets from immune cells and allow nutrient and metabolite transfer.…”

Three-dimensional cell culture: the missing link in drug discovery

“…Hydrogels used in this manner are often porous. This allows oxygen, nutrients and drugs to reach the proliferating cells and also facilitates removal of waste molecules; thus providing appropriate cell culture conditions [41]. The size of pores in a hydrogel can be manipulated as necessary during production [42], enabling hydrogels to be engineered to suit experimental requirements, for example, for hypoxia or drugbased studies.…”

Control of the pore architecture in three-dimensional hydroxyapatite-reinforced hydrogel scaffolds

“…In contrast, natural and synthetic hydrogels mimic the extracellular matrix owing to their high water content and chemical similarity. In addition to their use as scaffolds or bioreactors, reinforced hydrogels that can endure significant mechanical loads are expanding their potential application in drug delivery systems, actuators and artificial muscles, sensors and conductors, photoresponsive gels, cosmetics and food applications [31][32][33][34][35][36][37][38][39]. The two hydrogels employed in this work to fabricate the scaffolds, agarose [40][41][42] and gellan [43][44][45][46], besides their traditional uses, have recently gained a new appreciation in the biomaterials and drug delivery research fields.…”