Investigating the Impact of Biomaterial Chirality on Host-Material Interactions

Abstract

Wound healing is a complex process that often culminates in scar tissue rather than functional regeneration, representing a major clinical challenge. Biomaterials provide a means to reshape these mechanistic pathways to improve healing outcomes beyond closure rates alone. Microporous annealed particle (MAP) scaffolds are particularly advantageous in the wound healing space due to their modularity and superior tissue integration compared to traditional nanoporous systems. This work characterizes the immune engagement underlying the regenerative capacity of D-chiral MAP (DMAP) scaffolds and directly compares it to an L-chiral (LMAP) scaffold with equivalent mechanical and chemical properties. We first examined T cell populations implicated in hair follicle neogenesis and T cell-dependent humoral responses. Contrary to our initial hypothesis, these T cell populations were neither recruited nor expanded in the DMAP-treated mice. To capture the broader microenvironmental landscape, we investigated DMAP using a time-course proteomic analysis. DMAP promoted a broad enrichment of immune-related pathways at day 4, followed by enrichment of keratinization and lipid-associated Gene Ontology (GO) pathways by days 14 and 21. As DMAP-mediated regeneration was previously shown to depend on adaptive immunity, we next assessed the role of infiltrating and resident lymphocytes in the regenerative mechanism. Regenerative repair persisted even when lymphocyte infiltration was restricted, indicating that infiltrating adaptive immune cells are not required. Instead, DMAP activated B cells in the skin draining lymph nodes, driving germinal center formation, the production of biomaterial-specific antibodies, and pro-regenerative serum factors. Remarkably, this circulating milieu was sufficient to confer regenerative healing even in wounds treated with LMAP. Finally, we investigated dendritic cell (DC) involvement in the repair mechanism through both comprehensive wound flow profiling and simplified in vitro assays. DMAP supported the accumulation of DCs that were activated but non-inflammatory. In vitro culture of bone marrow-derived DCs demonstrated direct maturation only in MAP scaffolds with the D-amino acid peptide in a crosslinker format. Taken together, these findings demonstrate that an early immune response, coordinated humoral immunity, and key innate-adaptive linking cells are central to DMAP’s function as a regenerative biomaterial.