siRNA Knockdown of Tissue Inhibitor of Metalloproteinase-1 in Keloid Fibroblasts Leads to Degradation of Collagen Type I Investigators evaluated the role played by knockdown of tissue inhibitors of metalloproteinases (TIMPs) in keloid formation, they transduced human keloid-derived fibroblasts with small interfering RNAs (siRNAs) targeting TIMP-1 or -2 using a lentiviral vector and assessed the biological effects. [J Invest Dermatol] Abstract Young Developmental Age Cardiac Extracellular Matrix Promotes the Expansion of Neonatal Cardiomyocytes In Vitro The extracellular matrix (ECM) is altered during heart development, and studies suggest that it plays an important role in regulating myocyte proliferation. The effects of fetal, neonatal and adult cardiac ECM on the expansion of neonatal rat ventricular cells in vitro were studied. [Acta Biomater] Abstract Loss of Extracellular Matrix from Articular Cartilage Is Mediated by the Synovium and Ligament after Anterior Cruciate Ligament Injury Post-traumatic osteoarthritis may be initiated by early expression of proteolytic enzymes capable of causing degradation of the articular cartilage at time of injury. The authors investigated the production of three of these key proteases in multiple joint tissues after anterior cruciate ligament injury and subsequent markers of cartilage turnover. [Osteoarthritis Cartilage] Abstract Extracellular Matrix Collagen Alters Cell Proliferation and Cell Cycle Progression of Human Uterine Leiomyoma Smooth Muscle Cells To better understand the pathogenesis of uterine leiomyomas (ULs) and the role of extracellular matrix collagens in their growth, scientists investigated the interaction of leiomyoma smooth muscle cells with two different forms of collagen, non-polymerized collagen and polymerized collagen, in the absence or presence of platelet-derived growth factor, an abundant growth factor in ULs. [PLoS One] Full Article Integrin-Specific Control of Focal Adhesion Kinase and RhoA Regulates Membrane Protrusion and Invasion Scientists demonstrated that loss of β1 but not β3 integrins leads to increased spread cell area and focal adhesion number in cells on 2D immobilized fibronectin. Increased adhesion numbers in β1 knockdown cells correlated with decreased cell migration on 2D surfaces. [PLoS One] Full Article Antigen-Specific B Lymphocytes Acquire Proteoglycan Aggrecan from Cartilage Extracellular Matrix Resulting in Antigen Presentation and CD4+ T Cell Activation The authors showed that B cells are highly efficient at extracting integral components of the extracellular matrix (ECM) for subsequent presentation. In particular they demonstrated that B cells specific for aggrecan, an integral component of cartilage ECM, acquire this rheumatoid arthritis candidate autoantigen in both a BCR- and a contact-dependent manner. [Immunology] Abstract The Naïve Effector Cells of Collagen Type I during Acute Experimental Pancreatitis Are Acinar Cells and Not Pancreatic Stellate Cells Researchers investigated the expression of collagen type I and the mRNA level of its regulatory factor, TGF-β1, in tissue samples of acute pancreatitis and aimed to determine the significance of collagen type I in predisposition to pancreatic fibrosis during acute pancreatitis. [Biochem Biophys Res Commun] Abstract |