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Effect of Discoidin Domain Receptors on Biomimetic Matrix Mineralization

Farzadi, Arghavan
http://rave.ohiolink.edu/etdc/view?acc_num=osu1563447989534881

Abstract Details

2019, Doctor of Philosophy, Ohio State University, Biomedical Engineering.
Collagen fibrils serve as the major template for mineral deposits in both biologically derived and engineered tissues. In recent years certain non-collagenous proteins have been elucidated as important players in differentially modulating intra vs. extra-fibrillar mineralization of collagen. We and others have previously shown that the expression of the collagen receptors, discoidin domain receptors (DDR1 and DDR2) positively correlate with mineralization of the extra-cellular matrix (ECM). While the role of DDR-mediated cell-signaling in modulating ECM mineralization is an active area of research, very little is understood on how DDRs influence the location, type and quality of mineral deposits in the ECM. This study employs a biomimetic approach to take a closer look at naturally derived ECM and its mineralization by DDRs. The first chapter provides a brief overview of the components of the extracellular matrix (ECM) and their role in modulating mineralization. We also summarize our current understanding of DDRs in modulating ECM mineralization. The first aim of this thesis (Chapter 2) was to examine if the ectodomain (ECD) of DDR2 modulates intra versus extra-fibrillar mineralization of collagen independent of cell-signaling. For this purpose, a decellularized collagenous substrate, namely glutaraldehyde fixed porcine pericardium (GFPP) was subjected to biomimetic mineralization protocols. GFPP was incubated in modified simulated body fluid (mSBF) or polymer-induced liquid precursor (PILP) solutions in the presence of recombinant DDR2 ECD (DDR2-Fc) to mediate extra or intra- fibrillar mineralization of collagen. Thermogravimetric analysis revealed that DDR2-Fc increased mineral content in GFPP calcified in mSBF while no significant differences were observed in PILP mediated mineralization. Electron microscopy approaches were used to evaluate the quality and quantity mineral deposits. An increase in the matrix to mineral ratio, frequency of particles and size of mineral deposits, was observed in the presence of DDR2-Fc in mSBF. The EDS map and spectra of mineralized collagen confirmed the presence of calcium phosphate and DDR2 ECD did not change the composition. However, Raman spectra and electron diffraction pattern of calcium phosphates confirmed the deposition of crystalline hydroxyapatite in the presence of DDR2 ECD. The second aim of this thesis (Chapter 3) was to investigate the interaction of DDR2 ECD with collagen and the mineral phase and its influence on mineralization. Von Kossa staining and The third aim of this thesis (Chapter 4) was to study the effect of genetically modified ECM on matrix mineralization. For this purpose, de-cellularized aortic tissue derived from DDR1 knock-out (KO) mice and wildtype littermate were subjected to the biomimetic mineralization protocols. Matrix mineralization of the resulting tissue was analyzed using histochemical stains and electron microscopy. Von kossa staining indicated that tissues from wildtype mice exhibited enhanced mineral deposition when incubated in mSBF and PILP as compared to DDR1 KO. A major site of mineralization was the elastin lamella present in the medial layer of the aorta. Ultrastructural analysis of collagen fibrils revealed that extrafibrillar mineralization was enhanced in fibrils from the wild-type mice. Endogenous mineralization of aortic valves was attenuated in DDR1 KO mice consistent with our results using biomimetic protocols. Finally, in chapter 5, we summarize the role of DDRs at the cell-matrix interface in modulating the location, type and quality of ECM mineralization and its implications in health and disease.immunohistochemistry analysis of adjacent sections indicated that recombinant DDR2-Fc bound to both the matrix and the mineral phase of GFPP subjected to biomimetic protocols. Further, DDR2-Fc was found to bind to hydroxyapatite (HAP) particles and enhance the nucleation of mineral deposits in mSBF solutions independent of collagen. Taken together, our observations elucidate DDR2 ECD as a novel player in the modulation of extra-fibrillar mineralization of collagen by binding to native collagen, binding to HAP and promoting nucleation of HAP.
Gunjan Agarwal (Advisor)
Lakshmi, P. Dasi (Committee Member)
Brian, L. Foster (Committee Member)
106 p.
Biomedical Engineering
Hydroxyapatite, Biomimetic mineralization, Pericardium

Recommended Citations

Citations

  • Farzadi, A. (2019). Effect of Discoidin Domain Receptors on Biomimetic Matrix Mineralization [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1563447989534881

    APA Style (7th edition)

  • Farzadi, Arghavan. Effect of Discoidin Domain Receptors on Biomimetic Matrix Mineralization . 2019. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1563447989534881.

    MLA Style (8th edition)

  • Farzadi, Arghavan. "Effect of Discoidin Domain Receptors on Biomimetic Matrix Mineralization ." Doctoral dissertation, Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1563447989534881

    Chicago Manual of Style (17th edition)

osu1563447989534881
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This open access ETD is published by The Ohio State University and OhioLINK.