Extracellular matrix (ECM) materials have diverse physiological functions by themselves and can also act as reservoirs of cytokines and growth factors, so that they can affect the cell phenotype, attachment, migration and proliferation of cells.
CHAPTER II: In this study, firstly a chondrocyte-derived extracellular matrix (CD-ECM) scaffold derived from porcine chondrocyte was evaluated for whether it can support and maintain chondrogenesis of rabbit mesenchymal stem cells (rMSCs) in vitro and in the nude mouse model in vivo. The initially formed cartilaginous tissues turned into bone matrix with time centripetally from the outside of the region as observed by Safranin-O and von Kossa stains. This phenomenon progressed much more rapidly in the PGA scaffold than in the ECM scaffold. In the ECM scaffold, the chondrogenic phenotypes of rMSCs were also maintained longer than in the PGA scaffold. These results suggest that the ECM scaffold not only strongly supports chondrogenic differentiation of rMSCs, but also helps maintain its phenotype in vivo.
CHAPTER III: The present study investigated the positive correlation among the loss of chondrogenic phenotypes, hypertrophic change and vessel invasion. Rabbit MSCs were subjected to chondrogenic differentiation in CD-ECM or PGA scaffold for 1 week in vitro and implanted in the back of nude mice for 6 weeks in vivo. The area showing loss of chondrogenic phenotypes in Safranin-O stain was correlated well with the mineralized area in the von kossa stain and the area with vessel-like structure in the Gomori aldehyde fuchsin stain at 6 weeks in terms of their size and distribution. This phenomenon progressed much more rapidly in the PGA constructs than in the CD-ECM constructs, and correlated well with the loss of chondrogenic phenotypes overall. Overall, this study showed that tissue engineered cartilage using the CD-ECM scaffold maintained better chondrogenic phenotypes in vivo and showed lower levels of hypertrophic changes and vessel invasion in particular.
CHAPTER IV: In this study, the chondrocyte-derived ECM (CD-ECM) was evaluated for inhibit vessel invasion in vitro and in vivo. Human umbilical vein endothelial cells (HUVECs) were plated on bio-membrane made of CD-ECM and human amniotic membrane (HAM) in vitro. The adhesion, proliferation, and tube formation activity of HUVECs were examined. Also, the CD-ECM and HAM powders were mixed individually in Matrigel and injected subcutaneously into nude mice in vivo. The vessel invasion into Matrigel was examined after 1 week. The adhesion and proliferation of HUVECs were more efficient on the HAM membrane than on the CD-ECM membrane. The vessel invasion also occurred more deeply and intensively in Matrigel containing HAM than in the one containing CD-ECM in vivo. In summary, the CD-ECM biomaterial promises to be beneficial implant material for cartilage repair, chondrogenic differentiation of MSCs and non-permissive properties for unfavorable endothelial cells.
Key word: Chondrocyte-derived extracellular matrix (CD-ECM), Mesenchymal stem cells (MSCs), Hypertrophic change, Degeneration, Vessel invasion, angiogenic factor, Endothelial cell