The effects of stepped structures of hydroxyapatite surface on the mRNA expression profile of immature dendritic cells

Hydroxyapatite (HA) has significant clinical promise for the repair of bone defects and the modification of implant material interfaces. However, after implantation, there are potential risks of chronic inflammation. Dendritic cells (DCs) are key cells in regulating chronic inflammatory responses, and their phenotype and functions are influenced by the surface structure of materials. Therefore, in order to provide some theoretical guidance for the optimal design of HA surface structures, this study tried to construct stepped structures on HA surfaces and investigate the effects of stepped structures on the cytoskeletal, cellular morphology, and mRNA expression profile of immature dendritic cells (imDCs). HA dishes with stepped structures were prepared utilizing the principle of oriented attachment growth, and subsequently used to construct in vitro cell culture models. The imDCs were observed by immunofluorescence staining to characterize their cytoskeleton structures and cellular morphology. Besides, transcriptome sequencing was used to examine the changes in the mRNA expression profile of imDCs. The results indicated that the stepped structures exposed on HA surfaces would increase the spread area of imDCs and affect the cell adhesion morphology. In addition, the results of the transcriptome sequencing revealed significant alterations in the mRNA expression profile, with differentially expressed genes (DEGs) predominantly enriched in the pathways associated with the focal adhesion signal pathway, the chemokine signal pathway, and the IL-17 signal pathway. Thus, the stepped structures could modulatethe cellular morphology and the immunological functions of imDCs by modulating the aforementioned signal pathways, including the focal adhesion pathway, the chemokine signaling pathway, and the IL-17 signaling pathway, thereby affecting the immune response process.