Developing Injectable Porous Gels to Deliver Viable Cells via Phase Separation

• Biomedical Applications
• Polymeric Materials
• Research Center for Macromolecules and Biomaterials

Cell transplantation therapy uses stem cells or other cell types to regenerate damaged organs caused by disease or injury.
The cells are encapsulated in polymer gels and injected into the body. 
Akihiro Nishiguchi has successfully developed gels that enhance both graft survival and cell viability.

Porous structures improve the performance of cell transplantation

Spinal cord injuries and myocardial infarction currently lack established treatments. In regenerative medicine, cell transplantation therapy is emerging as a highly promising method. Among these approaches, the use of injectable gels to encapsulate cells for direct delivery into the body is gaining particular attention.

Injectable gels are designed to remain liquid in a syringe and solidify in response to specific stimuli after being administered, allowing them to stay at the target site. However, injected gels often fail to properly engraft onto target organs. Even when engraftment succeeds, the transplanted cells frequently undergo apoptosis.

Apoptosis occurs because the polymeric chains of injectable gels are densely crosslinked. This dense structure hinders the diffusion of oxygen and nutrients essential for cell growth and survival. It also prevents recipient tissue cells from infiltrating the gel, weakening intercellular communication necessary for successful integration. To address these challenges, many researchers are exploring porous gels.

“Most injectable porous gels developed so far feature pore sizes in the nanometer range,” Nishiguchi explained. “While exploring the potential use of injectable gels as tissue adhesives, I discovered a method to create gels with micro-sized pores that are more suitable for cell growth.”