Interaction between a 3D collagen matrix used for periodontal soft tissue regeneration and T-lymphocytes: An in vitro pilot study

Abstract

Previous experimental models showed that activation of the immune system, particularly T cells, is required for optimal healing following wounds or surgery in the oral cavity. Therefore, studies to explore the interactions between the immune system and the collagen matrix are mandated. The specific aim of the present study was to analyze the interactions between T lymphocytes and a resorbable three-dimensional (3D) collagen matrix routinely used for soft tissue regeneration during periodontal surgery. Peripheral venous blood samples were collected from five patients. Following Ficoll-Paque separation, mononuclear cells were grown on fully resorbable 3D collagen matrices for 5 days. Lymphocytes were analyzed by flow cytometry for different surface markers, including CD4, CD8, CD38 and CD69. Cell viability and late apoptosis/necrosis were assessed in each group using an apoptosis assay based on Annexin V/propidium iodide staining. After 5 days in contact with the collagen matrix, the T cells expressed different surface markers. The overall T cell population increased significantly in the collagen matrix group compared to the respective controls (31.9±6.5 vs. 38.7±3.8%). CD8 and CD69 also increased significantly compared to their controls (CD69: 19.7±3.0 vs. 27.1±4.5% for collagen vs. control groups). At the same time, CD4 and CD38 expression was similar in both groups. Viability and apoptosis/necrosis were also identical in the samples and controls. These results show that the interaction between the collagen matrix and the immune cells stimulated activation of T cells and did not impair the healing process.

Keywords: T-lymphocytes; apoptosis; collagen matrix; oral mucosa; wound healing.

Figure 1.

Representative dot plots of unstimulated T cells (control) and collagen matrix-activated T cells. A representative dot plot for the unstimulated T cells (control) is shown in (A), and a representative dot plot for the collagen matrix-activated T cells is shown in (B), displaying an increase in the percentage of cytotoxic T cells.

Figure 1.

Representative dot plots of unstimulated T cells (control) and collagen matrix-activated T cells. A representative dot plot for the unstimulated T cells (control) is shown in (A), and a representative dot plot for the collagen matrix-activated T cells is shown in (B), displaying an increase in the percentage of cytotoxic T cells.

Figure 2.

Representative dot plots for unstimulated T cells (control) and collagen matrix-activated T cells. A representative dot plot for the unstimulated T cells (control) is shown in (A), and a representative dot plot for the collagen matrix-activated T cells is shown in (B), displaying surface modifications of the CD69 activation marker.

Figure 2.

Representative dot plots for unstimulated T cells (control) and collagen matrix-activated T cells. A representative dot plot for the unstimulated T cells (control) is shown in (A), and a representative dot plot for the collagen matrix-activated T cells is shown in (B), displaying surface modifications of the CD69 activation marker.

Figure 3.

Lymphocyte immunophenotypes: T and non-T cells were immunophenotyped. The unstimulated T cells were compared to collagen matrix-activated T cells following 5 days of incubation. *P<0.05.

Figure 4.

Lymphocyte viability: Τhe viability of unstimulated T cells, expressed as percentage of total cells, was compared to the viability of collagen matrix-activated T cells. Cells in late stages of apoptosis of necrosis were included in the cell death/cellular death levels.