Analysis of collagen gel degradation in an experimental cell culture model using fibroblasts isolated from peri-implantitis lesions

Background. Periodontitis and peri-implantitis are chronic inflammatory diseases that lead to progressive connective tissue degradation and alveolar bone resorption. The presence of characteristic periodontitis-associated fibroblasts (PAFs) that display a remarkably high capacity for extracellular matrix (ECM) degradation was previously reported in periodontitis lesions. Objectives. The aim of the study was to analyze collagen gel degradation in an experimental cell culture model using fibroblasts isolated from peri-implantitis lesions. Material and methods. A patient-derived experimental cell culture model of periodontitis was developed. Gingival tissues were obtained during peri-implant, periodontal, and tooth extraction surgeries. Fibroblasts isolated from tissues affected by peri-implantitis, mixed in a three-dimensional (3D) collagen gel, were co-cultured with gingival epithelial cells. The degree of collagen gel degradation was analyzed using gel contraction, and a histologic examination was performed. Results. In 5 examined cases, gel contraction was observed in the 3D co-culture model to considerably different degrees, which may demonstrate the presence of peri-implantitis-associated fibroblasts (PIAFs) that display a high capacity for collagen degradation. Histologically, the collagen gels with PIAFs showed numerous vacuoles adjacent to the cells when compared to gels with normal fibroblasts. The PIAFs from one case showed a rapid and significantly elevated level of collagen gel degradation in comparison to the PIAFs from the other cases. Conclusions. The study revealed the presence of PIAFs among the fibroblasts isolated from peri-implantitis lesions, displaying a capacity for collagen degradation. Further detailed studies are required to clarify the characteristics of PIAFs as well as their role in the occurrence and progression of peri-implantitis.