Faculty Advisor or Committee Member

Kristen L. Billiar, Advisor

Faculty Advisor or Committee Member

George D. Pins, Committee Member


Daniel Gibson




The purpose of this research was to study the synthesis and remodeling of extracellular matrix (ECM) by fibroblasts with special emphasis on the culture environment (media composition and initial ECM composition) and the resulting mechanical integrity of the ECM. This was investigated by culturing fibroblasts for 3 weeks in a variety of culture conditions consisting of collagen gels, fibrin gels, or media permissive to the self-production of ECM (Cell-Derived Matrix), and quantifying the mechanics of the resulting ECM. The mechanical characteristics were related to the biochemistry of the resulting ECM, notably in terms of collagen accumulation and collagen fibril diameters. The ultimate tensile strength (UTS) of the collagen gels and fibrin gels at the end of the 3-week period was 168.5 ± 43.1 kPa and 133.2 ± 10.6 kPa, respectively. The ultimate tensile strength of the cell-derived matrices was 223.2 ± 9 kPa, and up to 697.1 ± 36.1 kPa when cultured in a chemically-defined medium that was developed for the rapid growth of matrix in a more defined environment. Normalizing the strength to collagen density resulted in a UTS / Collagen Density in these groups of 6.4 ± 1.9 kPa/mg/cm3, 25.9 ± 2.4 kPa/mg/cm3, 14.5 ± 1.1 kPa/mg/cm3, and 40.0 ± 1.9 kPa/mg/cm3, respectively. Cells were synthetically more active when they produced their own matrix than when they were placed within gels. The resulting matrix was also significantly stronger when it was self-produced than when the cells rearranged the matrix within gels that corresponded to a significantly larger fraction of non-acid and pepsin extractable collagen. These studies indicate that cell-derived matrices have potential both as in vitro wound healing models and as soft connective tissue substitutes.


Worcester Polytechnic Institute

Degree Name



Biomedical Engineering

Project Type


Date Accepted





tension, failure strain, mechanics, fibroblasts, regenerative medicine, serum-free, UTS, proteoglycans, thickness, glycosaminoglycans, extensibility, collagen, wound-healing model, cell-remodeled matrix, cell-derived matrix, fibroblast-populated, collagen gel, biomechanical characterization, fibrin gel, strength, chemically-defined medium, growth factors, tissue growth, tissue regeneration, total protein content, human, tissue formation, biochemical characterization, Extracellular matrix, Fibroblasts, Biomechanics, Biochemistry, Wound healing