Injectable hybrid hydrogels enhance macrophage communication via second messenger amplification

Area of Science:

• Biomaterials Science
• Immunology
• Regenerative Medicine

Background:

• Macrophages are crucial for tissue repair via efferocytosis, but controlling their communication is challenging due to broad second messenger effects.
• Current interventions for macrophage regulation face limitations due to systemic and off-target effects.

Purpose of the Study:

• To develop an injectable, apoptosis-mimicking hybrid hydrogel (PAS@Gel) for specific macrophage intervention.
• To enhance macrophage communication and efferocytosis by targeting both first and second messengers.
• To promote tissue regeneration through optimized macrophage signaling.

Main Methods:

• Fabrication of an ECM-mimicking hybrid hydrogel incorporating apoptosis-mimicking vesicles (PAS).
• Incorporation of Rolipram within PAS to inhibit phosphodiesterase 4 (PDE4) and modulate cyclic adenosine monophosphate (cAMP) levels.
• In vitro assessment of macrophage receptor activation (Tyro3-Axl-Mer), RAC1, and cAMP pathways.
• In vivo evaluation using a myocardial ischemia/reperfusion (MI/R) injury model.

Main Results:

• PAS@Gel demonstrated synergistic activation of macrophage efferocytosis-related pathways in vitro.
• In vivo studies showed PAS@Gel effectively reduced inflammation and promoted myocardial tissue repair post-MI/R injury.
• The hydrogel specifically targeted macrophage first and second messenger pathways, enhancing intracellular signaling.

Conclusions:

• The developed PAS@Gel hydrogel offers a novel strategy for precise macrophage regulation in tissue regeneration.
• Targeting macrophage second messenger pathways via biomaterials can overcome limitations of traditional interventions.
• This approach holds promise for enhancing immune responses and promoting healing in various injury models.