Massachusetts Institute of Technology Harvard Medical School Brigham and Women’s/Massachusetts General Hosp. VA Boston Healthcare System 2.79J/3.96J/BE.441/HST522J CELL-MATRIX INTERACTIONS M. Spector, Ph.D. Cell Extracellular Matrix 4 mm 10 μm Articular Cartilage Chondrocytes (P2 Canine) in a Type I Collagen-GAG Scaffold Image removed due to copyright considerations. “Control Volume” B. Kinner UNIT CELL PROCESSES Concept of a “Control Volume” around a Cell Cell + Matrix Product + Soluble (Regulator) Regulator B “Control Volume” Soluble Regulator A COLLAGEN-GAG MATRICES: MODEL BIOMATERIALS (ANALOGS OF EXTRACELLULAR MATRIX) Investigation of cell interactions (UCPs) in vitro ? Type I (bovine and porcine) ? Type II (porcine) ? Chondroitin 6-sulfate Image removed due to copyright considerations. 1mm Image removed due to copyright considerations. ? Freeze-dried ? Dehydrothermally cross-linked ? Additional cross-linking 500μm IV Yannas, et al. PNAS, 1989 CELL –MATRIX INTERACTIONS WITH COLLAGEN-GAG MATRICES IN VITRO ? Cell interactions with the scaffold – Mitosis, migration, synthesis, and contraction, and their interrelationships ? Can provide insights into scaffold composition and structure for improved performance in regenerative medicine ? Can provide insights into cell behavior in vivo Chondrocytes (Passage 2 Canine) in a Type I Collagen-GAG Matrix Live cell imaging for a period of 5 hours. Image removed due to copyright considerations. J. Cheng CELL –MATRIX INTERACTIONS ? Mitosis ? Migration ? Synthesis ? Contraction Chondrocyte (P2 Canine) in a Type I Collagen-GAG Matrix: Mitosis Image removed due to copyright considerations. J. Cheng DNA Content 0 10 20 30 40 50 60 0102030 Day DNA ( u g ) DHT UV GTA EDAC CR Lee, et al., Biomat. 2001;22:3145 Mean ± SEM Effects of Cross-Linking on Chondrocyte Proliferation in Type I Collagen-GAG Matrices Inc. x-linking CELL –MATRIX INTERACTIONS ? Mitosis ? Migration ? Synthesis ? Contraction Chondrocytes (P2 Canine) in a Type I Collagen- GAG Matrix: Migration and Contraction Image removed due to copyright considerations. B. Kinner CELL –MATRIX INTERACTIONS ? Mitosis ? Migration ? Synthesis ? Contraction nmol nmol /hour/ /hour/ μ μ g DNA g DNA Protein Synthesis; Proline Incorporation 0 0.05 0.1 0.15 2 7 15 29 Day Proteoglycan Synthesis; Sulfate Incorporation 0 0.01 0.02 0.03 2 7 15 29 Day UV GTA EDC Effects of Cross-Linking on Chondrocyte Biosynthesis in Collagen-GAG Matrices DHT CR Lee, et al., Biomat. 2001;22:3145 CELL –MATRIX INTERACTIONS ? Mitosis ? Migration ? Synthesis ? Contraction Chondrocytes (P2 Canine) in a Type I Collagen-GAG Matrix: Contraction Image removed due to copyright considerations. 40 min B Kinner Non-Seeded: 8 days 21 days Image removed due to copyright considerations. Image removed due to copyright considerations. Non-Seeded and Cell-Seeded Collagen-GAG Scaffolds S. Vickers Cell-Mediated Contraction 30 40 50 60 70 80 90 100 0102030 Day % O r i g i n al D i am et er DHT UV GTA EDAC Mean ± SEM CR Lee, et al., Biomat. 2001;22:3145 Adult canine articular chondrocytes (passage 3) contract a type I collagen-GAG matrix, reflected in the decrease in diameter Little x-link., low modulus Highly x-link., high modulus CELL –MATRIX INTERACTIONS ? What are the interrelationships among UCPs: mitosis, synthesis and contraction? BIOMATERIALS-TISSUE INTERACTIONS Cell + Matrix Connective Tissue Epithelia Muscle Nerve BIOMATERIALS-TISSUE INTERACTIONS Cell + Matrix Connective Tissue Epithelia Muscle Nerve Adhesion Protein Collagen Biomaterial BIOMATERIALS-TISSUE INTERACTIONS Cell + Matrix Connective Tissue Epithelia Muscle Nerve Adhesion Protein Collagen Biomaterial Integrin “UNIT CELL PROCESSES” Cell + Matrix Mitosis Synthesis Migration Contraction Endocytosis Exocytosis UCP Connective Tissue Epithelia Muscle Nerve