Valentin, Jolene Elizabeth
(2010)
Macrophage Involvement in the Remodeling of an Extracellular Matrix Scaffold.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
The remodeling response to extracellular matrix (ECM) scaffold materials such as porcine small intestinal submucosa (SIS) is characterized by intense mononuclear cell infiltration during the first 4 weeks post-implantation. Persistence of macrophages in wounds is typically diagnosed as chronic inflammation with downstream formation of scar tissue and/or foreign body reaction, but ECM scaffolds remodel into organized site-specific tissue. Macrophages can express either proinflammatory (M1) or immunomodulatory and tissue remodeling (M2) phenotypes. Processing methods used during the manufacturing of ECM scaffolds can influence macrophage phenotype and downstream remodeling outcome.In the first study, human monocyte-derived macrophages were cultured on SIS and carbodiimide (CDI) crosslinked SIS in 20% and 6% oxygen concentrations. Macrophage phenotype was evaluated by expression of M1 (CXCL10 and CCR7) and M2 (ARG-1, CCL13, CCL18, and MRC-1) gene markers, and secretion of CXCL10, CCL13, CCL18, and MMP9. Macrophages cultured on SIS expressed an M2 profile, while macrophages cultured on CDI-SIS expressed a mixed M1/M2 profile. No consistent patterns were observed when comparing oxygen concentrations.The second study used radioactive 14C-labeled scaffolds to measure ECM scaffold degradation in a rodent model of musculoskeletal reconstruction with and without the depletion of macrophages. Tissues were characterized by expression of M1 (iNOS and IFN-ã) and M2 (ARG-1 and IL-10) gene markers, and cell surface markers CD68 (pan-macrophage), CCR7 (M1), and CD163 (M2). Results showed that macrophages are required for early and rapid degradation of SIS scaffolds, and that CDI-SIS is resistant to macrophage-mediated degradation. Furthermore, depletion of macrophages resulted in an attenuated inflammatory response and slowed the rate of scaffold degradation.The third study determined the contractile response and histomorphologic appearance of tissue repaired with SIS, CDI-SIS, or autologous tissue at 26 weeks after implantation. Contractile properties and fatigue resistance of remodeled tissue and of contralateral native tissue were assessed using an in-situ methodology. Muscle fiber-type distribution, blood vessel density and distribution, and innervation were determined. The tissue repaired with SIS showed complete replacement by tissue that histologically and functionally resembled native muscle. CDI-SIS was characterized by chronic inflammatory response and produced little to no measurable tetanic force output.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
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| ETD Committee: |
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| Date: |
26 January 2010 |
| Date Type: |
Completion |
| Defense Date: |
2 November 2009 |
| Approval Date: |
26 January 2010 |
| Submission Date: |
15 October 2009 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Bioengineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
contractility; ECM; hypoxia; M1; musculoskeletal; SIS; M2; phenotype |
| Other ID: |
http://etd.library.pitt.edu/ETD/available/etd-10152009-125605/, etd-10152009-125605 |
| Date Deposited: |
10 Nov 2011 20:03 |
| Last Modified: |
19 Dec 2016 14:37 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/9474 |
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