Both ionically and enzymatically crosslinkable alginate-tyramine conjugate as materials for cell encapsulation

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Regenerative Medicine

Background:

• Cell-enclosing capsules are crucial for cell transplantation therapies.
• Minimizing capsule swelling under physiological conditions is essential for successful transplantation.
• Alginate is a common biomaterial but exhibits significant swelling.

Purpose of the Study:

• To develop cell-enclosing capsules with minimal swelling using an alginate-tyramine conjugate.
• To evaluate the swelling behavior, cytotoxicity, and cell culture capabilities of the developed conjugate.
• To assess the potential of this material for cell therapy.

Main Methods:

• Synthesis of alginate-tyramine conjugate via carbodiimide/active-ester coupling.
• Crosslinking of the conjugate using calcium ions and peroxidase-catalyzed oxidative coupling.
• Assessment of swelling in saline compared to unmodified alginate.
• Evaluation of cytotoxicity using encapsulated cells.
• Long-term culture of encapsulated cells and measurement of mitochondrial activity.

Main Results:

• The alginate-tyramine conjugate gel exhibited significantly less swelling in saline than unmodified alginate.
• Swelling degree was controllable by adjusting conjugate preparation conditions.
• The conjugate gel demonstrated no obvious cytotoxicity to encapsulated cells.
• Encapsulated cells maintained viability and showed increased mitochondrial activity (approx. 5.2-fold) after 51 days of culture.

Conclusions:

• The alginate-tyramine conjugate is a promising biomaterial for developing low-swelling cell-enclosing capsules.
• This material supports long-term cell viability and function, crucial for effective cell therapy.
• The tunable swelling properties offer advantages for optimizing capsule performance in vivo.