Abstract Body: Introduction
Our lab developed a tissue-engineered biologic composed of human neonatal fibroblasts (NDFs) and iPSC-cardiomyocytes (CMs) on a bioresorbable mesh that promotes cardiac repair in immunocompetent preclinical chronic heart failure (CHF) models. The implanted cells are not detected after 30-days yet still impart long-term improvements. Here, we explored the immune response to the biologic using spatial transcriptomics.
Aims
We aim to define the biologic secretome and evaluate how the spatiotemporal transcriptome level changes in treated myocardium are mediated through immune and stromal cell mechanisms.
Methods
Mass spectrometry proteomics compared the biologic secretome before and after CM seeding onto NDF+mesh constructs. Mice (C57BL/6) underwent left coronary artery ligation, developed CHF over three weeks prior to biologic treatment. Spatial transcriptomics were evaluated at weeks 1, 2, and 4 post-treatment. Regions of interests (ROIs) were divided into border, infarct, and biologic zones using Masson’s trichrome stain. Three cell types of interest obtained from each ROI were marked via immunofluorescence (IF) with CD45, Desmin, a-smooth muscle actin, and Sytox green.
Results
Proteomics revealed a dynamic shift in the biologic secretome post-CM seeding, with extracellular matrix organization as a top enriched pathway, suggesting active paracrine signaling toward the endogenous cells. Spatial transcriptomics demonstrated this was accompanied by a significant (p<0.05) M1-to-M2 macrophage (MP) shift, with TREM2+ MPs and FOXP3+ T cells validated by IF. Cell-cell communication analysis identified signaling from the biologic via the CC Chemokine Ligand (CCL), Tenascin-C, and EphB pathways, with cell proportion analyses revealing a transition from blood progenitor-dominated at week 1 to effector populations including MPs, Tregs, and B cells at weeks 2 and 4. Echocardiographic and histological data suggest functional improvements as early as one week post-treatment.
Conclusions
These studies show that the biologic patch mediates cardiac repair through paracrine-driven immunomodulation. Proteomics suggest the biologic secretome drives a coordinated immune response characterized by an M1-to-M2 MP shift, increase of reparative effector cells, and a novel TREM2+ MP and FOXP3+ T cell population. Ongoing single-cell multiomic profiling aims to further understand underlying epigenetic and transcriptomic mechanisms.