Defense Date


Document Type


Degree Name

Doctor of Philosophy


Biomedical Engineering

First Advisor

Dr. Jennifer Puetzer

Second Advisor

Dr. Henry Donahue

Third Advisor

Dr. Rene Olivares-Navarrete

Fourth Advisor

Dr. Lesley Chow

Fifth Advisor

Dr. Seth Cheatham


The anterior cruciate ligament (ACL) connects to bone via structurally complex attachments known as entheses. Entheses are composed of gradients in organization, composition, mineralization, and cell phenotype and are critical for proper load transfer between mechanically dissimilar elastic ligaments and stiff bone. Currently, these gradients are not restored in natural healing, repair, or in engineered replacements, yielding limited repair options and high failure rates, demonstrating the need to develop native-like entheses for improved functional and lasting repair. The collective focus of this work was to drive development of native-like entheses in engineered ligaments by mimicking developmentally inspired mechanical cues. We found that compressive boundary clamps, which restrict cellular contraction and produce a zonal tensile-compressive environment at the clamping interface, guide ligament fibroblasts to produce multizonal, early postnatal-like enthesis gradients in organization and composition. Further, the addition of βTCP under these clamps enhanced maturation of these engineered entheses mirroring development via endochondral ossification (Chapter 2). Next, the application of developmental mechanical cues mimicking growth rate and cyclic muscle loading were found to differentially drive maturation of entheses in ACL fibroblast seeded engineered ligament constructs (Chapter 3). Based on the exciting findings we found of this culture system driving ACL fibroblasts to form immature entheses, we were interested in evaluating whether these mechanical cues were enough to drive human mesenchymal stem cells (hMSCs) to differentiate and produce similar zonal entheses. Static mechanical cues were found to drive zonal stem cell differentiation and accelerated early postnatal-like enthesis gradients in hMSC seeded constructs (Chapter 4). Further, application of dynamic mechanical cues drove further maturation and differentiation of hMSC constructs beyond early postnatal-like development towards later postnatal enthesis development with more mature native-like gradients in collagen organization, matrix composition, and cell phenotype (Chapter 5). Collectively, developmental mechanical cues were able to drive the development of some of the most physiologically appropriate engineered entheses to date. Further, this work established and characterized a promising in vitro culture system that closely mirrors native enthesis development. This is a promising platform for use in future studies to investigate and understand how mechanical cues can further improve enthesis regeneration efforts moving forward.


© Michael Ethan Brown

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VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission


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