26 In vitro and ex vivo models to test the anti-inflammatory and regenerative effects of small molecules in osteoarthritis
Osteoarthritis (OA) is the most common type of arthritis and one of the main causes of pain and disability in the elderly. It is associated with inflammation and a breakdown of cartilage in knee and hip joints. Currently, no drugs have proved convincing disease modifying efficacy. There is an urgent need to explore disease-modifying OA drugs that can alleviate, prevent, or even reverse the development of OA. In our previous study, small molecule compounds extracted from Traditional Chinese Medicine showed significant anabolic and inflammation preventing effects on human OA cartilage cells (chondrocytes) in vitro. Furthermore, to explore more promising small molecules, six small molecules (RCGD 423, Wogonin, XAV-939, Zingerone, THSG, and Paeonol) with potential regenerative and anti-inflammatory effects were evaluated for their cytotoxicity on human OA chondrocytes in vitro. Zingerone, THSG and Paeonol at 1 to 50 μM did not affect chondrocytes viability and all the 6 compounds did not show cytotoxic effect at 1 μM. Apart from the in vitro screening, the pre-clinical ex vivo explant culture model mimics more the physiological condition in evaluating therapeutic effects for OA. The aim of the study is to assess the anti-inflammatory and regenerative effects of selected compounds first in a 3D cell culture in vitro, and then in a bioreactor guided ex vivo model. The outcomes of these selected compounds will be investigated under physiological and degenerative mechanical loading on the human OA cartilage explants or bovine explants. The extracellular matrix production and the gene expression, of anabolic, catabolic, and inflammatory markers will be evaluated. Histological analysis will be applied to reveal proteoglycan and collagen deposition.