pO₂ reporter composite hydrogel macroencapsulation devices for magnetic resonance imaging oxygen quantification

Area of Science:

• Biomaterials Engineering
• Transplantation Science
• Medical Imaging

Background:

• Hydrogel cell encapsulation is crucial for allogeneic transplantation, minimizing immunosuppression.
• Macroencapsulation offers advantages but faces oxygen transport limitations at clinical scales.
• Accurate in vivo oxygen measurement is vital for optimizing macroencapsulation device design.

Purpose of the Study:

• To engineer oxygen-reporting hydrogels (PORCH) for in situ oxygen tension measurement.
• To integrate PORCH with proton imaging of siloxanes to map tissue oxygenation levels (PISTOL) MRI.
• To assess PORCH's accuracy and cytotoxicity for macroencapsulation devices.

Main Methods:

• Engineered two PORCH incorporation methods: emulsion and microbeads.
• Co-encapsulated PORCH with cells in hydrogel devices.
• Quantified oxygen tension in vitro using PISTOL MRI and assessed cytotoxicity.

Main Results:

• Both emulsion and microbead PORCH enabled accurate in situ oxygen quantification via PISTOL MRI.
• The emulsion-based PORCH approach demonstrated superior spatial resolution.
• PORCH hydrogels showed no significant cytotoxicity to co-encapsulated cells.

Conclusions:

• PORCH hydrogels are a viable tool for spatiotemporal oxygen monitoring in macroencapsulation devices.
• This technology can guide the design of improved cell delivery systems for transplantation.
• Emulsion-based PORCH offers enhanced spatial resolution for oxygen mapping in cell therapies.