Coaxial Alginate Hydrogels: From Self-Assembled 3D Cellular Constructs to Long-Term Storage

Area of Science:

• Biomaterials Science
• Cell Biology
• Tissue Engineering

Background:

• Alginate is a biocompatible and biodegradable biomaterial widely used in biomedical applications.
• Its hydrogels support cell encapsulation for immunoisolation, 3D culture, and cell/drug delivery.
• Core-shell capsules offer advanced structures for cell encapsulation.

Purpose of the Study:

• To evaluate structural properties and swelling of core-shell capsules for multipotent stromal cell (MSC) encapsulation.
• To assess 3D culture and slow-freezing cryopreservation of MSCs within these capsules.
• To determine the optimal alginate type and cryoprotectant for capsule stability and cell viability.

Main Methods:

• Core-shell capsules were fabricated using coaxial electrospraying.
• Multipotent stromal cells were encapsulated, cultured for 35 days, and cryopreserved.
• Cell viability, metabolic activity, and cell-cell interactions were analyzed.
• Cryopreservation parameters were optimized using cell-free capsules.

Main Results:

• High-G alginate core-shell capsules demonstrated superior stability during in vitro culture compared to high-M alginate.
• These capsules promoted viable self-assembled cellular structures and maintained MSC functionality better than solid beads.
• 0.3 M sucrose improved capsule integrity and 3D cell assembly viability compared to 10% DMSO.

Conclusions:

• Core-shell capsules made from high-G alginate are advantageous for MSC encapsulation, 3D culture, and cryopreservation.
• The developed workflow supports the creation of stable, functional 3D cell constructs.
• This strategy shows promise for the off-the-shelf availability of encapsulated MSCs.