In vitro and in silico modeling of cellular and matrix-related changes during the early phase of osteoarthritis

Abstract

Objective: Understanding the pathophysiological processes of osteoarthritis (OA) require adequate model systems. Although different in vitro or in vivo models have been described, further comprehensive approaches are needed to study specific parts of the disease. This study aimed to combine in vitro and in silico modeling to describe cellular and matrix-related changes during the early phase of OA. We developed an in vitro OA model based on scaffoldfree cartilage-like constructs (SFCCs), which was mathematically modeled using a partial differential equation (PDE) system to resemble the processes during the onset of OA.Design: SFCCs were produced from mesenchymal stromal cells and analyzed weekly by histology and qPCR to characterize the cellular and matrix-related composition. To simulate the early phase of OA, SFCCs were treated with interleukin-1β (IL-1β), tumor necrosis factor α (TNFα) and examined after 3 weeks or cultivated another 3 weeks without inflammatory cytokines to validate the regeneration potential. Mathematical modeling was performed in parallel to the in vitro experiments.Results: SFCCs expressed cartilage-specific markers, and after stimulation an increased expression of inflammatory markers, matrix degrading enzymes, a loss of collagen II (Col-2) and a reduced cell density was observed which could be partially reversed by retraction of stimulation. Based on the PDEs, the distribution processes within the SFCCs, including those of IL-1β, Col-2 degradation and cell number reduction was simulated. Conclusions:By combining in vitro and in silico methods, we aimed to develop a valid, efficient alternative approach to examine and predict disease progression and new therapeutic strategies.

An in vitro human-based fracture gap model – Mimicking the crosstalk between bone and immune cells

“…The applied technique patented by Ponomarev et al . 23 exploits the capacity of MSC to undergo mesenchymal condensation on a macroscale to produce macro-tissues in a highly reproducible standardized manner without causing necrosis formation in the center 24 . The advantage of such macroscale approaches is the physiologically relevant size, geometry, low cell number and density compared to the matrix and mechanical properties when compared to e.g.…”

“…The advantage of such macroscale approaches is the physiologically relevant size, geometry, low cell number and density compared to the matrix and mechanical properties when compared to e.g. spheroids 24 . However, the generation and examination of these constructs are time-consuming and require high numbers of cells limiting the throughput of the system but enabling the performance of several analyses from one model.…”

“…H&E staining was performed as described previously 24 . In short, slices were fixed with 4 (v/v) % PFA (10 min), washed with distilled water and stained with Harris’s hematoxylin solution (Merck Millipore).…”