Controlled fibroblast directional motility, self-organization and synthetic capacity are fundamental to connective tissue development, growth, remodeling and repair. However, the signals which drive these aspects of fibroblast behavior are poorly understood. It is becoming increasingly clear that fibroblasts in mesenchymal tissue possess intrinsic patterning and synthetic potential and, under appropriate conditions, could be harnessed to repair or regenerate highly-organized connective tissues such as the corneal stroma. In mammalian stromal development, neural crest-derived mesenchymal cells invade the prospective corneal space, organize themselves, then produce, extend and subsequently maintain stromal extracellular matrix (ECM) architecture under increasing intraocular pressure. Our understanding of this process is quite limited, particularly with respect to 1) drivers of inital corneal mesenchymal/fibroblast cell patterning, 2) mechanisms of local and global control of matrix deposition and 3) mechanisms which guide tissue extension (growth) under mechanical force. Our limited appreciation of factors which control matrix deposition, retention and resorption extends to tissue regeneration including stromal wound healing, scar resolution and implant remodeling. It has been a dogmatic belief that the highly-organized collagenous arrays found in the stroma are refractory to in situ regeneration (particularly in humans). Our long-term basic science goals are to determine how highly-organized connective tissue is constructed, extended during growth, maintained, repaired and remodeled. Our long-term translational goals are to utilize this knowledge to formulate new approaches to corneal wound repair and regeneration. To accomplish the long term goals, it is necessary to first determine what factors control fibroblast organizational behavior during matrix production and to determine by what mechanism they control the orientation and retention of deposited collagen. The specific objective of this proposal is to investigate the effect of mechanical signaling on the organization synthesis and retention of collagenous matrix. To accomplish this objective, we will utilize our expertise in live, dynamic cell imaging, bioreactor design, mechanobiology and mechanochemistry. Our central hypothesis for this proposal is that mechanical signaling provides a robust and persistent guidance cue to corneal fibroblasts which is capable of 1) controlling the global organization of the cells, 2) guiding the deposition and preferential retention of collagen and 3) controlling tissue growth. To examine these hypotheses we will utilize our recently developed mechanobioreactor which permits live, long-term imaging of fibroblasts during the production of tissue. Loads of varying magnitude will be placed on a culture system and the output of the cells will be recorded on a minute-to-minute basis. The results of the proposed investigations should not only fully test the central hypothesis, but provide quantitative details about the levels of force necessary to stimulate and control the behavior of PCFs during matrix production.

Public Health Relevance

Completion of this proposal will provide insight into the basic science of how mechanics influences cells during the production of highly-organized tissue such as the corneal stroma. The proposed work will also investigate the role of mechanical force in guiding the chemistry associated with the assembly of load-bearing tissue. Ultimately, we expect that the work will lead to better approaches to tissue engineering and a deeper understanding of the role that mechanics plays in the construction of vertebrate connective tissue.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
2R01EY015500-07
Application #
8387865
Study Section
Special Emphasis Panel (BVS)
Program Officer
Mckie, George Ann
Project Start
2004-04-01
Project End
2015-08-31
Budget Start
2012-09-01
Budget End
2013-08-31
Support Year
7
Fiscal Year
2012
Total Cost
$388,750
Indirect Cost
$138,750
Name
Northeastern University
Department
Engineering (All Types)
Type
Schools of Engineering
DUNS #
001423631
City
Boston
State
MA
Country
United States
Zip Code
02115
Paten, Jeffrey A; Siadat, Seyed Mohammad; Susilo, Monica E et al. (2016) Flow-Induced Crystallization of Collagen: A Potentially Critical Mechanism in Early Tissue Formation. ACS Nano 10:5027-40
Tonge, Theresa K; Ruberti, Jeffrey W; Nguyen, Thao D (2015) Micromechanical Modeling Study of Mechanical Inhibition of Enzymatic Degradation of Collagen Tissues. Biophys J 109:2689-2700
Paten, Jeffrey A; Tilburey, Graham E; Molloy, Eileen A et al. (2013) Utility of an optically-based, micromechanical system for printing collagen fibers. Biomaterials 34:2577-87
Flynn, Brendan P; Tilburey, Graham E; Ruberti, Jeffrey W (2013) Highly sensitive single-fibril erosion assay demonstrates mechanochemical switch in native collagen fibrils. Biomech Model Mechanobiol 12:291-300
Flynn, Brendan P; Tilburey, Graham E; Ruberti, Jeffrey W (2013) Erratum to: Highly sensitive single-fibril erosion assay demonstrates mechanochemical switch in native collagen fibrils. Biomech Model Mechanobiol 12:847
Wang, Lina; Johnson, Joshua A; Chang, David W et al. (2013) Decellularized musculofascial extracellular matrix for tissue engineering. Biomaterials 34:2641-54
Saeidi, Nima; Guo, Xiaoqing; Hutcheon, Audrey E K et al. (2012) Disorganized collagen scaffold interferes with fibroblast mediated deposition of organized extracellular matrix in vitro. Biotechnol Bioeng 109:2683-98
Mega, Yair; Robitaille, Mike; Zareian, Ramin et al. (2012) Quantification of lamellar orientation in corneal collagen using second harmonic generation images. Opt Lett 37:3312-4
Saeidi, Nima; Karmelek, Kathryn P; Paten, Jeffrey A et al. (2012) Molecular crowding of collagen: a pathway to produce highly-organized collagenous structures. Biomaterials 33:7366-74
Chang, Shu-Wei; Flynn, Brendan P; Ruberti, Jeffrey W et al. (2012) Molecular mechanism of force induced stabilization of collagen against enzymatic breakdown. Biomaterials 33:3852-9

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