Chemoattractive Properties of Cytokines Towards Stro-1⁺ DPSCs

Objectives: The aim of this work was to determine whether odontoblasts secrete specific cytokines that are chemotactic for Stro-1 sorted DPSCs.
Methods: DPSCs were isolated from mixed dental pulp cell cultures using magnetically activated cell sorting (MACS), based on the expression of the mesenchymal stem cell (MSC) marker Stro-1. Sorted cells were assessed for their expression of MSC and hematopoietic cell surface markers using flow cytometry. Odontoblasts-like cells were differentiated from dental pulp cells using beta-glycerophosphate, as described previously by us. The odontoblast-like cells were stimulated with lipoteichoic acid (LTA) and the secretome of the cells was screened for the presence of 43 growth factors and cytokines using a commercially available array (Abcam UK). Selected cytokines were assessed for their ability to induce the migration of DPSCs using a transwell migration assay.
Results: Following cell sorting, >98% of Stro-1⁺ DPSCs were shown to express the MSC markers CD73, CD90, CD105 and CD44. <1% of the Stro-1⁺ DPSCs were positive for the hematopoietic markers CD45, CD34, CD11b, CD19 and HLA-DR. Treatment of the odontoblasts with LTA resulted in an increase several cytokines including GRO-α, IL-8, IL-6 and MCP-1. MCP-1 was found to induce Stro-1⁺ DPSC migration in a dose-dependent manner.
Conclusions: This work identifies a potential pathway whereby odontoblasts are able to recruit DPSCs to the site of injury through the secretion of MCP-1.