A new form of directed cell migration, called mechanotaxis (or durotaxis), in which both speed and directional persistence are influenced by substrate mechanical properties, has been recently described in the literature. Exploiting mechanotaxis therapeutically, in conjunction with chemotaxis and haptotaxis, may represent a new approach to designing biomaterials that provide the appropriate combinations of chemical and mechanical cues to promote the selective migration of osteoblasts (or mesenchymal stem cells) from surrounding healthy tissue into small bony defects. Prior to pursuing craniofacial tissue engineering applications, additional basic science studies addressing the relevance of mechanotaxis for bone, combined with efforts to determine the mechanisms by which cells sense their local mechanical environment to initiate a program of cell motility, are required. This R03 application proposes a set of feasibility studies to determine if a pre-osteoblastic cell line (MC3T3-E1) will migrate via mechanotaxis on model substrates. Specifically, this proposal aims to: 1.) Fabricate polyacrylamide hydrogels with pre-defined mechanical compliance using a photopolymerization process, and to subsequently functionalize these hydrogels with extracellular matrix (ECM) proteins to support MC3T3-E1 adhesion and spreading; 2.) Quantify cell migration speed and directional persistence of MC3T3-E1 cells on ECM-modified hydrogel substrates possessing uniform stiffness, sharp interfaces in stiffness, or gradients in stiffness; and 3.) Determine what role, if any, is played by the Rho GTPases in sensing substrate compliance and regulating the mechanotactic response. Successful completion of these aims will not only provide useful fundamental data regarding cell migration mechanisms, but may also guide future osteoconductive strategies that exploit this mechanotaxis paradigm. Such strategies will be explored in the applicant's future R21 and R01 proposals. ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Dental & Craniofacial Research (NIDCR)
Type
Small Research Grants (R03)
Project #
5R03DE016117-02
Application #
7083558
Study Section
NIDCR Special Grants Review Committee (DSR)
Program Officer
Lumelsky, Nadya L
Project Start
2005-07-01
Project End
2007-06-30
Budget Start
2006-07-01
Budget End
2007-06-30
Support Year
2
Fiscal Year
2006
Total Cost
$68,893
Indirect Cost
Name
University of California Irvine
Department
Biomedical Engineering
Type
Schools of Engineering
DUNS #
046705849
City
Irvine
State
CA
Country
United States
Zip Code
92697
Khatiwala, Chirag B; Kim, Peter D; Peyton, Shelly R et al. (2009) ECM compliance regulates osteogenesis by influencing MAPK signaling downstream of RhoA and ROCK. J Bone Miner Res 24:886-98
Kundu, Anup K; Khatiwala, Chirag B; Putnam, Andrew J (2009) Extracellular matrix remodeling, integrin expression, and downstream signaling pathways influence the osteogenic differentiation of mesenchymal stem cells on poly(lactide-co-glycolide) substrates. Tissue Eng Part A 15:273-83
Khatiwala, Chirag B; Peyton, Shelly R; Metzke, Mark et al. (2007) The regulation of osteogenesis by ECM rigidity in MC3T3-E1 cells requires MAPK activation. J Cell Physiol 211:661-72
Peyton, Shelly R; Ghajar, Cyrus M; Khatiwala, Chirag B et al. (2007) The emergence of ECM mechanics and cytoskeletal tension as important regulators of cell function. Cell Biochem Biophys 47:300-20
Khatiwala, Chirag B; Peyton, Shelly R; Putnam, Andrew J (2006) Intrinsic mechanical properties of the extracellular matrix affect the behavior of pre-osteoblastic MC3T3-E1 cells. Am J Physiol Cell Physiol 290:C1640-50
Kundu, Anup K; Putnam, Andrew J (2006) Vitronectin and collagen I differentially regulate osteogenesis in mesenchymal stem cells. Biochem Biophys Res Commun 347:347-57