Human Cartilage Repair with a Photoreactive Adhesive-Hydrogel Composite A poly(ethylene glycol) diacrylate hydrogel was designed to support cartilage matrix production, with easy surgical application. A model in vitro system demonstrated deposition of cartilage-specific extracellular matrix in the hydrogel biomaterial and stimulation of adjacent cartilage tissue development by mesenchymal stem cells. [Sci Transl Med] Abstract Promoting Reprogramming FGF2 Reveals that the Extracellular Matrix Is a Barrier for Reprogramming Fibroblasts to Pluripotency Recent evidence has revealed that reprogramming efficiency could be improved by fibroblast growth factors (FGF2), while the underlying molecular mechanism remains unknown. Here investigators dissected the roles of FGF2 in promoting mouse fibroblast reprogramming and disclosed the molecular mechanism behind this process. [Stem Cells] Abstract The IL-6 Trans-Signaling-STAT3 Pathway Mediates Extracellular Matrix and Cellular Proliferation in Fibroblasts from Hypertrophic Scar Researchers investigated the role of the IL-6 trans-signaling-signal transducer and activator of transcription 3 (STAT3) pathway in hypertrophic scar (HS) fibroblasts derived from post-burn HS skin. [J Invest Dermatol] Full Article PAK-PIX Interactions Regulate Adhesion Dynamics and Membrane Protrusion to Control Neurite Outgrowth The roles of P21-activated kinase (PAK) in the regulation of axon outgrowth downstream of extracellular matrix proteins are poorly understood. Here investigators showed that PAKs 1-3 and PIX are expressed in the developing spinal cord and differentially target to point contacts and filopodial tips within motile growth cones. [J Cell Sci] Abstract LPA1-Induced Cytoskeleton Reorganization Drives Fibrosis through Connective Tissue Growth Factor-Dependent Fibroblast Proliferation Using a mouse peritoneal fibrosis model, scientists demonstrated central roles for lysophosphatidic acid (LPA) and LPA1 in fibroblast proliferation. Genetic deletion or pharmacological antagonism of LPA1 protected mice from peritoneal fibrosis, blunting the increases in peritoneal collagen by 65.4 and 52.9%, respectively, compared to control animals and demonstrated that peritoneal fibroblast proliferation was highly LPA1 dependent. [FASEB J] Abstract Mutations in the Catalytic Domain of Human Matrix Metalloproteinase-1 (MMP-1) that Allow for Regulated Activity through the Use of Ca2+ By systematically creating point mutations in the catalytic and linker domains of human MMP-1, researchers generated a protein library amenable to physiological parameter-based screening. Mutants screened for temperature sensitive activity had mutations clustered at or near amino acids critical for metal binding. [J Biol Chem] Abstract | Full Article Effects of Cysteine Proteases on the Structural and Mechanical Properties of Collagen Fibers Excessive cathepsin K (catK) mediated turnover of fibrillar type I and II collagens in bone and cartilage leads to osteoporosis and osteoarthritis. The authors aimed to explore the structural and mechanical consequences of collagen fiber degradation by catK. [J Biol Chem] Abstract | Full Article Cleavage of Extracellular Matrix in Periodontitis: Gingipains Differentially Affect Cell Adhesion Activities of Fibronectin and Tenascin-C Fibronectin and tenascin-C are pericellular extracellular matrix glycoproteins present in periodontal tissues. Whereas fibronectin mediates fibroblast adhesion, tenascin-C binds to fibronectin and inhibits its cell-spreading activity. Using purified proteins in vitro, investigators asked whether fibronectin and tenascin-C are cleaved by gingipains at clinically relevant concentrations, and how fragmentation by the bacterial proteases affects their biological activity in cell adhesion. [Biochim Biophys Acta] Abstract Non-Destructive Analysis of Extracellular Matrix Development in Cardiovascular Tissue-Engineered Constructs Procollagen I carboxyterminal peptide, procollagen III aminoterminal peptide, tropoelastin and sulphated glycosaminoglycans were investigated for their potential use as non-destructive markers in culture medium of statically cultivated cell-seeded fibrin gels. [Ann Biomed Eng] Abstract |