Encapsulation of protein microfiber networks supporting pancreatic islets

Abstract

Networks of discrete, genipin-crosslinked gelatin microfibers enveloping pancreatic islets were incorporated within barium alginate microcapsules. This novel technique enabled encapsulation of cellular aggregates in a spherical fibrous matrix <300 μm in diameter. Microfibers were produced by vortex-drawn extrusion within an alginate support matrix. Optimization culminated in a hydrated fiber diameter of 22.3 ± 0.4 μm, a significant reduction relative to that available through current gelatin microfiber spinning techniques, while making the process more reliable and less labor intensive. Microfibers were encapsulated at 40 vol % within 294 ± 4 μm 1.6% barium alginate microparticles by electrostatic-mediated dropwise extrusion. Pancreatic islets extracted from Sprague Dawley rats were encapsulated within the microparticles and analyzed over 21 days. Acridine orange and propidium iodide fluorescent viability staining and light microscopy indicated a significant increase in viability for islets within the fiber-embedded particles relative to fiber-free controls at days 7, 14, and 21. The fiber-embedded system also promoted cellular aggregate cohesion, reducing the incidence of dispersed islet morphologies within the capsules from 31 to 8% at day 21. Further enquiry into benefits of islet encapsulation within a protein fiber network will be the subject of future investigation.

Mesenchymal stem cell 3D encapsulation technologies for biomimetic microenvironment in tissue regeneration

“…Microfluidic fibers can be formed with various polymers, including gelatin-hydroxyphenylpropionic acid, alginate, chitosan, gelatin, and poly (lactic-co-glycolic acid) (PLGA). Microfluidic spinning is the proper technology for cell encapsulation because the fibers can be continuously produced and cover the cells without the need for a high voltage or temperature [63]. In microfluidics, PDMS-based and glass-based microfluidic chips are mainly used.…”

“…In microfluidics, PDMS-based and glass-based microfluidic chips are mainly used. These types of devices are easily extruded using similar materials and methods [63, 64]. Liu et al reported mouse BMSC encapsulated alginate microfibers using microfluidic technology for vascular grafts [65].…”

The emerging field of pancreatic tissue engineering: A systematic review and evidence map of scaffold materials and scaffolding techniques for insulin-secreting cells

“…37–42 Gelatin is the denaturized form of collagen but differs in some important characteristics such as gelation time and the presentation of binding site sequences. 43…”

“…[37][38][39][40][41][42] Gelatin is the denaturized form of collagen but differs in some important characteristics such as gelation time and the presentation of binding site sequences. 43 Synthetic scaffold materials. The most frequently used synthetic material investigated in the reviewed studies was PEG and its derivatives poly(ethylene glycol) diacrylate (PEGDA) and poly(ethylene glycol) dimethacrylate (PEGDM) (n = 53 in total).…”

Molecular Imaging of Pancreatic Islet Transplantation

“…Various imaging markers have been co-encapsulated with islets, such as SPIOs integrated with near-infrared fl uorescent Cy5.5 dye for 1 H MRI and optical imaging [ 44 ] , perfl uorocarbons for 19 F MRI, ultrasound, and CT [ 60 ] , and gold nanoparticles coated with Gd chelates for 1 H MRI, CT and ultrasound [ 61 ] . The inside of the capsule can also be modifi ed into a protein microfi ber network to better support the embedded islets [ 62 ] . Moreover, Kim et al developed "capsule-in-capsules" containing gold and iron nanoparticles for MRI, CT and ultrasound [ 63 ] , in which the islets were not only separated from the immune system but also from the nanoparticles to prevent potential toxic eff ects of the iron.…”