RNA Isolation from Articular Cartilage The isolation of high-quality RNA from articular cartilage is a notoriously challenging task. This is due to the tissue's low cellularity and the presence of a dense extracellular matrix rich in proteoglycans. These molecules, which are highly cross-linked and negatively charged, interfere with RNA extraction, often resulting in low yield and poor RNA quality. Traditional methods are designed for larger cartilage specimens, typically weighing at least 25 mg. However, these methods are unsuitable for smaller samples, such as those obtained from focal cartilage defects, which are usually less than 3 mg. This limitation has necessitated the development of improved protocols tailored for small tissue inputs. A new RNA isolation protocol was developed to address this need. It was designed to extract high-quality RNA from less than 3 mg of rabbit articular cartilage. The method combines TRIzol extraction with Proteinase K digestion, QIAshred...