Polymeric Materials for Cell Microencapsulation

Abstract

Mammalian cells have been microencapsulated within both natural and synthetic polymers for over half a century. Specifically, in the last 36 years microencapsulated cells have been used therapeutically to deliver a wide range of drugs, cytokines, growth factors, and hormones while enjoying the immunoisolation provided by the encapsulating material. In addition to preventing immune attack, microencapsulation prevents migration of entrapped cells. Cells can be microencapsulated in a variety of geometries, the most common being solid microspheres and hollow microcapsules. The micrometer scale permits delivery by injection and is within diffusion limits that allow the cells to provide the necessary factors that are missing at a target site, while also permitting the exchange of nutrients and waste products. The majority of cell microencapsulation is performed with alginate/poly-L-lysine microspheres. Since alginate itself can be immunogenic, for cell-based therapy applications various groups are investigating synthetic polymers to microencapsulate cells. We describe a protocol for the formation of microspheres and microcapsules using the synthetic polymer poly(ethylene glycol) diacrylate (PEGDA).

The effect of low-magnitude, high-frequency vibration on poly(ethylene glycol)-microencapsulated mesenchymal stem cells

“…Microspheres produced were polydisperse, with most ranging in diameter from 50 to 300 µm, as has been previously reported. 39 Cell density per microsphere was also non-uniform with <5% of microspheres having 0–10 cells in them. The majority of microspheres contained cells that comprised 46%–76% ± 5.3%–4.2% of the total microsphere volume.…”

“…Cells were microencapsulated as previously described. 39 Briefly, hMSCs were harvested and combined at 10 4 cells/μL with a hydrogel precursor solution containing 0.1 g/mL 10 kDa PEGDA (10% w/v; Laysan Bio), 37 mM 1-vinyl-2-pyrrolidinone with hydrophilic photoinitiators (1.5% (v/v) triethanolamine and 0.1 mM eosin Y) in HEPES-buffered saline (pH 7.4). A hydrophobic photoinitiator solution (2,2-dimethoxy-2-phenyl acetophenone in 1-vinyl-2-pyrrolidinone; 300 mg/mL) was combined in mineral oil (3 μL/mL, sterile filtered) and then subjected to vortex (2 s) under white light (Edmund Optics MH-100 metal halide lamp, 20 s) to photopolymerize the resulting emulsion.…”

The effect of polymer molecular weight and cell seeding density on viability of cells entrapped within PEGDA hydrogel microspheres

“…When initially developing this microencapsulation system, it was discovered that encapsulating cells based (Aijaz et al 2017).…”

“…In this study, we microencapsulate murine preosteoblast cells (MC3T3-E1) within polyethylene glycol diacrylate (PEGDA) hydrogel microspheres. The preosteoblast cells had been microencapsulated previously and had demonstrated their ability to survive the encapsulation process (Aijaz et al 2017). These cells are capable of differentiating into bone and thereby can be examined for tissue engineering purposes or can be transduced to release a desired product for use in cell therapy applications and the entrapping microsphere hydrogels can be tailored to serve as an immunoisolation carrier or as a soft tissuelike scaffold that can simulate the extracellular matrix of the cell.…”

Synthetic Polymers for Organ 3D Printing

“…The polymeric hydrogels for organ 3D printing include natural and synthetic polymers and their combinations. Natural polymeric chains are full of bioactive groups, which can provide a benign and stable environment for cells, especially stem cells, to grow, migrate, proliferate, and/or differentiate inside [10,11]. Synthetic polymeric networks are comprised of repeatable inert units.…”