Quantifying cellular protrusion in alginate capsules with covalently crosslinked shells.

Area of Science:

• Biomaterials Engineering
• Cell Encapsulation Technology
• Tissue Engineering

Background:

• Alginate capsules are widely used for cell encapsulation.
• Maintaining cell viability and controlling cell distribution within capsules is critical for therapeutic applications.
• Cell exposure at the capsule surface can trigger immune responses and compromise capsule integrity.

Purpose of the Study:

• To evaluate the viability and distribution of INS-1E beta cells within shell-crosslinked alginate capsules.
• To investigate the effectiveness of poly-l-lysine (PLL) and poly(methylvinylether-alt-maleic anhydride) (PMM50) in reinforcing capsule shells.
• To assess the impact of reinforced shells on preventing cell protrusion and escape.

Main Methods:

• INS-1E beta cells were encapsulated in alginate using air-shearing.
• Capsules were coated with poly-l-lysine (PLL) and 50% hydrolyzed poly(methylvinylether-alt-maleic anhydride) (PMM50) to form crosslinked shells.
• Cell viability and distribution, particularly near the capsule surface, were analyzed using 2D and 3D confocal colocalization mapping.

Main Results:

• Encapsulated INS-1E cells exhibited high viability and progressive clustering over six weeks.
• Approximately 30% of cells were initially within the 20 micrometer thick alginate-PLL-PMM50 shell.
• About 7% of cells protruded from the capsule surface, indicating random distribution.
• Reinforced shells showed potential in preventing significant cell exposure and escape.

Conclusions:

• Shell-crosslinked alginate capsules support high INS-1E beta cell viability and clustering.
• The crosslinked alginate-PLL-PMM50 shell effectively reinforces capsule surfaces.
• Reinforced capsule designs may mitigate immune responses and prevent cell escape, enhancing the safety and efficacy of cell encapsulation therapies.