Anti-Inflammatory Activity of a Demineralized Bone Matrix: An In Vitro Pilot Study

Abstract

Demineralized bone matrix (DBM) is commonly used for the reconstruction of bone defects. Early graft consolidation involves a transient inflammatory process. It is, however, unclear whether DBM can modulate this process. To test this possibility, we prepared acid lysates of demineralized ground cortical (DGC) and moldable demineralized fibers (MDF). Murine RAW 264.7 and primary bone marrow macrophages were exposed to acid lysates of DGC and MFD prior to provoking an inflammatory response with lipopolysaccharide (LPS). Similarly, murine ST2 mesenchymal cells were exposed to DGC and MFD with and without interleukin 1β (IL1) and TNFα. We show here that acid lysates of DGC and MFD reduced the expression of IL1 and IL6 in RAW 264.7 macrophages, as determined by RT-PCR and, for IL6, by immunoassay. This response was confirmed with primary macrophages. Likewise, desalted acid lysates exert anti-inflammatory properties on RAW 264.7 cells and in ST2 cells, the forced expression of IL6, inducible nitric oxide synthase (iNOS) and chemokine ligand 5 (CCL5) was reduced. These in vitro findings suggest that DGC and MFD lower the inflammation-induced expression of inflammatory mediators in murine cell-based bioassays.

Response of human peripheral blood monocyte-derived macrophages (PBMM) to demineralized and decellularized bovine bone graft substitutes

“…A previous study examined the inflammatory reaction caused by three different commercially available demineralized matrices (DBM) using a murine air pouch model, highlighting the importance of considering both efficacy and safety of materials and methods used for their processing when selecting a bone grafting method [ 41 ]. At the same time demineralized bone matrix (DBM) generated by yet another method exhibited a lower inflammation-induced expression of inflammatory mediators in murine cell-based bioassays [ 42 ]. However, current understanding allows modification of biomaterial physico-chemical design to support biomaterial-induced macrophage polarization for tissue regeneration [ 43 ].…”

“…However, current understanding allows modification of biomaterial physico-chemical design to support biomaterial-induced macrophage polarization for tissue regeneration [ 43 ]. In an in vitro pilot study by Panahipour et al ., it was found that DBM demonstrated anti-inflammatory activity by reducing the expression of IL-1β and IL-6 in RAW 264.7 macrophage cells, suggesting a potential modulation of the inflammatory responses [ 42 ]. Such conflicting results may be attributed to differences in the methodology of the studies, particularly in terms of the graft processing techniques utilized, which produced variable physico-chemical and topographical characteristics that elicit varying host tissue responses besides the likely presence of residual native cells within the grafts that may evoke the inflammatory responses.…”