In Vitro Comparison of Macrophage Polarization and Osteoblast Differentiation Potentials between Granules and Block Forms of Deproteinized Bovine Bone Mineral.

Masako Fujioka-Kobayashi,Michihide Kono,Richard J Miron,Hiroki Katagiri,Simon D Marjanowski,Benoit Schaller

doi:10.3390/ma13122682

Abstract

Deproteinized bovine bone mineral (DBBM) bone grafts are commonly utilized for guided bone regeneration (GBR) techniques in regenerative dentistry. It has been hypothesized that different forms (blocks versus particulates) might demonstrate the varying properties of cell behavior during the regenerative process. Therefore, the aim of the present study was to investigate DBBM granules and blocks for their effects on osteoblasts and macrophages (Mφs). DBBM granules and blocks were filled to the same size (φ6.4 mm in diameter × 2.0 mm in height) in cell culture wells and assessed for cell viability and cell differentiation of human osteoblast-like Saos-2 cells, and Mφs derived from human monocyte THP-1 cells. The two groups were first characterized by micro-CT analysis, which demonstrated that DBBM granules had a two-fold greater material volume and a four-fold larger surface area than the blocks. DBBM blocks showed superior viability for both osteoblasts and Mφs. Osteoblast experiments were then utilized to better characterize the influence of DBBM shapes/forms on osteoblast differentiation. Alkaline phosphatase (ALP) staining on the undecalcified frozen sections was observed throughout the DBBM granule surface, yet this staining was only observed on the upper portion of the DBBM blocks. Furthermore, DBBM blocks showed M1-Mφ polarization trends with higher IL-1 and IL-6 mRNA expression in Mφs, while the conditioned media from Mφs cultured on DBBM granules promoted osteoblast differentiation with higher mRNA levels of Runx 2, ALP and osteocalcin. In conclusion, the DBBM granules showed more regenerative effects, lower M1 marker expression, and higher osteoblast differentiation potential when compared with the blocks, which might be related to the larger material volume, higher surface area and greater ability for the cells to penetrate through the scaffold.

Highlights

Guided bone regeneration (GBR) is a surgical technique using bone grafting materials to support bone formation in osseous defects [1,2]
The quantitative results showed two-fold greater material volumes and a four-fold larger surface area in Deproteinized bovine bone mineral (DBBM) granules compared with the blocks, owing to ials 2020, 13, x FOR PEER REVIEW
DBBM granules showed a higher fill granules and blocks filled in a 6.4 mm diameter × 2 mm height cylinder. (A) Three-dimensional (3D)

Summary

Introduction

Guided bone regeneration (GBR) is a surgical technique using bone grafting materials to support bone formation in osseous defects [1,2]. Materials 2020, 13, 2682 owing to its osteoinductivity (bone-forming growth factors) and osteoconductivity (support of three-dimensional bone ingrowth within the scaffold), as well as providing osteogenic cells. Xenogenic bone substitutes, deproteinized bovine bone mineral (DBBM) granules have widely been utilized in regenerative dentistry for the management of periodontal bone defects, extraction socket preservation, alveolar ridge augmentation, and sinus floor elevation without disease transmission [5]. Despite very limited material resorption, over the years, DBBM granules have provided excellent osteoconductivity and new bone stability without adverse effects [6,7]. More recently, a block form of DBBM has been brought to the market for cases requiring a ridge contour increase or volume stability of the augmented region [8]

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