The degradation of chondrogenic pellets using cocultures of synovial fibroblasts and U937 cells

Abstract

Osteoarthritis (OA) of the knee is often characterized by joint space narrowing on X-ray, knee pain, and a loss of joint function through progressive cartilage degradation and intermittent synovial inflammation. The objective of this work was to develop an in vitro model in a clinically relevant system. Normal human synovial fibroblasts were cultured with U937 cells for 3 days then combined with a chondrogenic stem cell pellet for another 4 days. This culture system mimicked many of the aspects of early stage OA including production of cytokines and degradative enzymes, MMP-1 and MMP-3, resulting in a conditioned medium profile similar to OA synovial fluid. This catabolic environment resulted in the release of glycosaminoglycan (GAG) from the pellet. In a similar manner to early stage OA, the pellet had increased aggrecan and collagen II expression. All of these effects are hallmarks of early stage OA. This relatively simple tissue model containing a 3D cartilage component interacting with synoviocytes and macrophages could be useful to understand early causes and progression of OA. It can be scaled easily thus useful for high throughput screening of disease modifying drugs in a clinically relevant system.

Corticosterone suppresses IL-1β-induced mPGE2 expression through regulation of the 11β-HSD1 bioactivity of synovial fibroblasts in vitro

“…Synovial fibroblasts and osteoblasts generate active glucocorticoids through the expression of 11β-HSD1 (7). Such activity increases, in vitro , in response to pro-inflammatory cytokines or glucocorticoids.…”

A Three-Dimensional Chondrocyte-Macrophage Coculture System to Probe Inflammation in Experimental Osteoarthritis

“…[24][25][26][27] Indeed, an increasing number of studies recently reporting in vitro OA models have cultured chondrocytes within 3D microenvironments. [28][29][30][31][32] However, important auxiliary cell types such as macrophages have continued to be cultured in 2D, 28,31,33 despite the primary location of the macrophages in the knee joint being within the synovial membrane. Moreover, phenotypic changes in macrophages cocultured with chondrocytes have largely been unexplored in previous in vitro studies.…”

Adapted chondrogenic differentiation of human mesenchymal stem cells via controlled release of TGF-β1 from poly(ethylene oxide)-terephtalate/poly(butylene terepthalate) multiblock scaffolds

“…Furthermore, the low amounts of GAG released in the culture medium from pellets cultured in the presence of TGF‐β1‐loaded scaffolds suggest a similar integrity of the GAG content of the extracellular matrix compared to pellets cultured in the presence of soluble TGF‐β1. The presence of GAG released in the culture medium is known to be associated with a pathologic upregulation of MMPs and inflammatory cytokines . In vitro chondrogenic differentiation of MSCs in the presence of TGF‐β induces the expression of multiple cartilage‐specific molecules including type‐II collagen and aggrecan, but may additionally promote the expression of chondrocyte hypertrophy‐associated genes including type‐X collagen, ALP, and MMP‐13 .…”

“…The presence of GAG released in the culture medium is known to be associated with a pathologic upregulation of MMPs and inflammatory cytokines. 34,42 In vitro chondrogenic differentiation of MSCs in the presence of TGF-b induces the expression of multiple cartilage-specific molecules including type-II collagen and aggrecan, 43,44 but may additionally promote the expression of chondrocyte hypertrophy-associated genes including type-X collagen, ALP, and MMP-13. 39,45 Here, the TGF-b1-loaded scaffolds increased the expression of type-II collagen of 700-fold and aggrecan of 200-fold compared with that obtained with supplementation of the factor in medium, reflected also in the highest score of immunoreactivity to type-II collagen compared with all the other groups.…”