Background/Purpose: Osteoporosis is a bone disease characterized by low bone mass and changes in bone architecture, often leading to pain, fractures and reduced mobility in affected patients. Glucocorticoid-induced osteoporosis (GIOP) is known as the most important form of secondary osteoporosis. To set up a GIOP in vitro model, we established and characterized a human in vitro bone model, subsequently using methylprednisolone to induce GIOP and later treat the model with anti-osteoporotic drugs.

Methods: To provide the basic scaffold for the structure of the bone model, mesenchymal stromal cells (MSCs)

were differentiated on β-TCP. Afterwards, human osteoclasts, differentiated from CD14⁺ monocytes, were added, and the models were treated with 10^-6 M methylprednisolone to induce osteoporosis. As pharmacological treatment of GIOP, we used alendronic acid and denosumab. Bone forming and resorbing activity was monitored using μ-computed tomography (µ-CT), supernatant analysis, gene expression, scanning electron microscopy and immunofluorescence.

Results: Results showed that a ratio of 10⁴ osteoblasts and 5*10³ osteoclasts works best. We furthermore analysed the supernatant and detected secretion of alkaline phosphatase (ALP), lactate dehydrogenase (LDH), osteoprotegerine (OPG), matrixmetallopeptidase 9 (MMP-9), free phosphate, and calcium. Our results confirmed the functionality of our 3D model. Subsequently, we transferred our untreated model to the osteoporosis-simulating model by treating with methylprednisolone and could show a disruption of bone homeostasis in favour of osteoclast activity. If these models were treated with alendronic acid or denosumab, markers of bone metabolism (Ca²⁺, ALP, bone volume) returned to pre-pathophysiological.

Conclusion: Ultimately, we obtained an in vitro 3D co-culture of osteoblasts and osteoclasts simulating human native bone capable of mimicking key aspects of GIOP in vitro via treatment with methylprednisolone. As a proof of concept, GIOP was treated with established antiresorptive drugs showing an increase of osteogenesis markers.

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