Background/Purpose: Osteoporosis is a bone disease characterized by low bone mass and changes in bone architecture, leading to pain and reduced mobility in patients. Glucocorticoid-induced osteoporosis (GIOP) is the best known form of secondary osteoporosis. Glucocorticoids (GC) are commonly used to treat inflammation, such as in rheumatic diseases. However, GC use can have a negative effect on the skeletal system and lead to osteoporosis.

(i) Establishing and characterizing a human in vitro bone model consisting of osteoblasts and osteoclasts embedded in β-TCP (“healthy” bone model), (ii) treatment with dexamethasone to induce GIOP (“osteoporotic” bone model) and (iii) using this model as a testing platform for the treatment of osteoporosis.

Methods: Our model includes osteoblasts and osteoclasts, which are mainly responsible for bone remodeling. We defined an osteoclast differentiation protocol using low-attachment plates and cultured the cells for 21 days in ∝MEM medium, 5% FCS, 5% human AB serum, 2 mmol L-glutamine, 25 ng/ml M-CSF, and 50 ng/ml RANKL. To provide the basic scaffold for the structure of the “healthy” bone model, mesenchymal stromal cells (MSCs) were seeded on β-tricalcium phosphate (β-TCP). This bone model, consisting of differentiated osteogenic cells, was fully characterized in our previous work [1].

Results: The multinuclearity, typical ß-actin ring formation, cellular activity by TRAP staining and functionality in resorption assays proved functional osteoclasts. Our protocol allowed us to passage these cells without cell loss or loss of function. To establish the previously “healthy” (i.e., untreated) bone model, we seeded osteoclasts onto a pre-seeded β-TCP construct and cultured the co-culture for 7 days. We then analyzed the supernatant and detected marked secretion of RANKL, MMP-9, and free phosphate. This indicates the functionality of both osteoclasts and osteoblasts in our 3D model. Subsequently, the healthy model will be transferred to the osteoporosis-simulating model where treatment with dexamethasone will be applied. Once established, we plan to use the model we have developed for in vitro preclinical trials to test marketed drugs.

Conclusion: Ultimately, we will obtain an in vitro 3D co-culture of osteoblasts/osteoclasts simulating human native bone, which will be treated with dexamethasone to mimic key aspects of GIOP in vitro.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/generation-of-a-human-3d-in-vitro-bone-model-that-mimics-glucocorticoid-induced-osteoporosis/