Methods: Pulp tissues were engineered by culturing SHED in a poly-L-lactic acid tooth/scaffold. After 14 days, LPS (5 μg/ml) or saline was added into the culture medium, followed by incubation for 4 hours. The tissues were processed for formaldehyde-fixed, demineralized paraffin sections and immunoperoxidase-stained for CD68. Then, CD68-expressing cells in cell rich areas where most of the scaffold had been absorbed were retrieved by using laser capture microdissection, and subjected to real-time PCR analysis of class II MHC, CD80, CD83 and CD86 mRNA expression.
Results: The expression levels of class II MHC, CD80, CD83, and CD86 mRNAs were significantly higher in the CD68-expressing cells retrieved from LPS-treated engineered pulp tissue, as compared with those from saline-treated engineered pulp tissues (P < 0.05).
Conclusions: CD68-expressing macrophages in the engineered pulp tissue showed upregulation of APC-related genes following LPS-challenge, suggesting that these cells are able to mature into potent APCs in response to LPS.