3D human osteoblast - osteoclast in vitro co-culture

Abstract

Bone remodeling is a complex, poorly understood process which replaces old and diseased bone with new functional bone. Deregulation of this process leads to increased bone resorption or bone formation resulting in several bone diseases like osteoporosis or osteopetrosis. It is crucial to understand the mechanisms behind bone remodeling to develop efficient therapies against such bone diseases. To enable the study of human bone remodeling in vitro, a 3D human osteoblast-osteoclast co-culture was established which aimed to link bone formation and bone resorption within a 3D mineralized silk scaffold. Human bone marrow derived mesenchymal stem cells were seeded onto silk scaffolds (d=5mm, h=3mm) and differentiated towards mineral producing osteoblasts within a spinner flask bioreactor. Mineralized silk - osteoblast constructs were seeded with human monocytes and differentiated towards osteoclasts. Mineral content was monitored via micro computed tomography. Prior to seeding, monocytes were pre-screened to assess osteoclastic differentiation and resorption potential. Silk scaffolds (n = 8) were successful mineralized over a period of 13 weeks. Initial mineralization occurred between week 3 and 5 of culture. Among four donors, donor 4 monocytes were selected as suitable cells for the co-culture showing the highest cell size, multinucleation, the highest resorption (60.03% of total mineral area resorbed) and extracellular TRAP levels (2.4 mmol/L). The co-culture constructs in bioreactor 1 showed a significant decrease in mean mineral volume (- 1.339 mm3) between day 12 and day 22 under static, osteoclastic conditions. Co-culture constructs in bioreactor 2 showed no significant decrease in mean mineral volume between day 4 and day 22. In this study, a co-culture between human osteoblasts and osteoclasts showing bone formation and bone resorption could be established. The presence of mature nucleated osteoclasts could not be concluded but assumed based on the present mineral resorption.

Date of Award	2019
Original language	English
Awarding Institution	Vienna University of Technology
Supervisor	Stefan Remmers (Supervisor 2), Johanna Melke (Supervisor 2), Sandra Hofmann (Supervisor 2), Keita Ito (Supervisor 2) & Andreas Teuschl (External coach)