(PR075) Characterizing the Role of Cell Adhesion Molecules in Stem Cell from Apical Papilla – Macrophage Interactions in a 3D Organoid Model

Objectives: The regeneration potential of Stem Cells from Apical Papilla (SCAP) is influenced by microenvironment, extra-cellular matrix, pro-inflammatory cytokines, and immune cells, particularly macrophages. Three-dimensional (3D) organoids are unique models to replicate this intricate environment, providing extracellular scaffolding and facilitating complex cell interactions. Juxtracrine interactions between macrophages and SCAP have been hypothesized to play an important role in this process, however, this remains largely unknown. This study will investigate the cell adhesion molecules that mediate cell-to-cell interactions between SCAP and macrophages in both an inflammatory (LPS) and healing (IL-4) environments using a 3D organoid model.

Methods: Two co-culture models were utilized: 2-dimensional (2D) co-culture and a 3D collagen-based organoid model. Each model included an unstimulated control and two experimental groups: IL-4 treated, and LPS treated. Samples were collected at 0, 2, 5 and 7 days and were subject to qPCR and immunocytochemistry. Experiments were conducted in triplicates and data analyzed by two-way ANOVA.

Results: Relative gene expression analysis shows that IL-4 induces CD200R expression, LPS induces ICAM-1 expression, and both IL-4 and LPS reduce the expression of CD11a. The 2D co-culture had higher expressions of CD200R and ICAM-1, while the 3D co-culture had a higher expression of CD200. Immunofluorescence analysis showed no effect of inflammatory conditions on protein expression within 2D co-cultures up to day 7.