Dermal fibroblast-derived thrombospondin 2 orchestrates extracellular matrix organization and influences wound healing

Summary: Abstract Body: Thrombospondin 2 (TSP2) is a matricellular protein that modulates extracellular matrix (ECM) dynamics through its influence on collagen fibrillogenesis and tissue remodeling. While global TSP2-null mice display marked skin abnormalities, the fibroblast-specific contribution of TSP2 to skin homeostasis and regeneration remains unknown. Given that PDGFRα labels a progenitor-enriched population of dermal fibroblasts, we utilized a PDGFRαCreER driver to selectively delete TSP2 in these cells. We performed an excisional wound splinting model on TSP2eGFP mice and PDGFRαCreER;TSP2 mice to evaluate wound closure dynamics, scab dissociation, and ECM architecture. Immunofluorescence and Second Harmonic Generation (SHG) imaging were conducted on normal and wounded skin sections to characterize PDGFRα+ fibroblasts,TSP2 expression patterns, and ECM organization. In TSP2eGFP mice, we observed dual PDGFRα+TSP2+ dermal fibroblasts within normal skin. Following injury, TSP2 signal increased significantly at 7 days post injury when compared to uninjured skin. Fibroblast-specific TSP2 deletion in PDGFRαCreER;TSP2 mice revealed a distinct ECM phenotype characterized by significant disorganization of dermal fibroblast alignment in the wound bed. Despite these disruptions, PDGFRαCreER;TSP2 mice exhibited a trend toward accelerated wound closure and earlier scab detachment, recapitulating key features of the global TSP2-null phenotype but revealing distinct, fibroblast-specific ECM defects. Our results indicate that fibroblast-specific TSP2 deletion disrupts normal ECM organization and impacts wound healing dynamics. Ongoing efforts aim to clarify the mechanisms by which TSP2 modulates fibroblast behavior and ECM remodeling, potentially uncovering new avenues for treating fibrotic skin conditions. Madysen Hunter¹, Dylan Feist¹, Neda Vishlaghi¹, Brandt Smith¹, Jahnu Saikia Saikia², Craig Duvall², Andrea Alford³, Robert Tower¹, Tristan Maerz³, Kurt Hankenson³, Benjamin Levi¹ 1. Center for Organogenesis, Regeneration, and Trauma, The University of Texas Southwestern Medical Center, Dallas, TX, United States. 2. Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, United States. 3. University of Michigan, Ann Arbor, MI, United States. Stem Cell Biology, Tissue Regeneration and Wound Healing