Chitosan and platelet-derived growth factor synergistically stimulate cell proliferation in gingival fibroblasts.

BACKGROUND AND OBJECTIVE Chitosan is a naturally derived polymer that may be applied in periodontal therapy for tissue-reconstruction purposes. Previous studies have shown that chitosan may stimulate tissue healing. However, reports exploring the cellular responses stimulated by chitosan are lacking. In the present study we analyzed whether chitosan may promote cell proliferation in primary cultures of human gingival fibroblasts. MATERIAL AND METHODS Chitosan particles were generated, and their size, zeta potential and morphology were characterized using transmission and scanning electron microscopy and zetasizer analysis. The biocompatibility of chitosan particles was analyzed using the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) cell-viability assay and by detecting the release of lactate dehydrogenase into the cell-culture medium. The total number of cells was estimated by staining with crystal violet followed by measurement of the absorbance at 560 nm on a microplate reader. Cell proliferation was studied by detecting proliferating cell nuclear antigen protein levels, immunofluorescence for Ki67 and incorporation of 5'-bromo-2'-deoxyuridine. RESULTS The sizes of the chitosan particles generated were in the micrometer and nanometer ranges. Cell viability was increased in the presence of chitosan. Moreover, the combination of chitosan and platelet-derived growth factor (PDGF-BB) potently stimulated cell viability, cell proliferation and activation of the ERK1/2 pathway involved in cell proliferation. CONCLUSIONS The present study shows that chitosan is well tolerated by gingival fibroblasts and is able to stimulate cell proliferation through the ERK1/2 signaling pathway. A synergistic response between chitosan and growth factors (such as PDGF-BB) may stimulate cell proliferation in gingival fibroblasts exposed to this biomaterial.