Identifying Critical Immune Effectors Of The Dermal Wound Healing Response By Innate Cells Using Microporous-Annealed-Particle (Map) Hydrogel

Abstract The wound healing response is critical to maintain tissue function after injury. Inflammation is needed to sterilize the wound site, but this results in scar formation and impaired tissue function. Topical anti-microbial use, fetal wound healing, and limited studies in germ-free animals suggest that the degree of microbial contamination at a wound site positively correlates with scar formation and recovery time. However, tools to identify the molecular signals and cell types that alter tissue repair verses have been limited. Here we test the hypothesis that Danger-Associated-Molecular Patterns (DAMPs) released during sterile injury guide a fundamentally distinct wound healing response than Pathogen-Associated-Molecular-Patterns (PAMPs) using a novel microporous annealed particle hydrogel (MAP-gel). MAP-gel is an immunologically inert, injectable tissue matrix that is easily linked to a broad range of small signaling molecules. We show that subcutaneous injection of MAP-gel is a robust platform to identify innate immune signaling molecules and infiltrating cell types that control wound healing. Conjugating the model PAMP, LPS, to MAP-gel is sufficient to induce a fibrotic encapsulation response and alter infiltrating immune cell populations. To identify the candidate modulators, proteins enriched in MAP-gels isolated from non-inflammatory or LPS-driven inflammatory responses were identified by LC-MS. These candidates are being conjugated directly to MAP-gel to identify immune effectors that promote wound healing with the absence of fibrotic encapsulation. The modified MAP-hydrogel will be used to gain insight into the molecular mechanisms behind scaring and the unique role DAMPs play in tissue resolution.