BMP4 micro-immunotherapy increases collagen deposition and reduces PGE2 release in human gingival fibroblasts and increases tissue viability of engineered 3D gingiva under inflammatory conditions

Abstract

Background: We aimed to evaluate the effect of low doses (LD) bone morphogenetic protein-2 (BMP2) and BMP4 micro-immunotherapy (MI) in two in vitro models of periodontal wound healing/regeneration. Methods: We first evaluated the effect of LD of BMP2 and BMP4 MI on a 2D cell culture using human gingival fibroblasts (hGF) under inflammatory conditions induced by IL1 beta. Biocompatibility, inflammatory response (Prostaglandin E2 (PGE2) release), collagen deposition and release of extracellular matrix (ECM) organization-related enzymes (matrix metalloproteinase-1 (MMP1) and metalloproteinase inhibitor 1 (TIMP1)) were evaluated after short (3 days) and long-term (24 days) treatment with BMP2 or BMP4 MI. Then, given the results obtained in the 2D cell culture, LD BMP4 MI treatment was evaluated in a 3D cell culture model of human tissue equivalent of gingiva (GTE) under the same inflammatory stimulus, evaluating the biocompatibility, inflammatory response and effect on MMP1 and TIMP1 release. Results: LD BMP4 was able to decrease the release of the inflammatory mediator PGE2 and completely re-establish the impaired collagen metabolism induced by IL1 beta treatment. In the 3D model, LD BMP4 treatment improved tissue viability compared with the vehicle, with similar levels to 3D tissues without inflammation. No significant effects were observed on PGE2 levels nor MMP1/TIMP1 ratio after LD BMP4 treatment, although a tendency to decrease PGE2 levels was observed after 3 days. Conclusions: LD BMP4 MI treatment shows anti-inflammatory and regenerative properties on hGF, and improved viability of 3D gingiva under inflammatory conditions. LD BMP4 MI treatment could be used on primary prevention or maintenance care of periodontitis.