The engineering of human reproduction is one of the defining scientific advances of the past century. Methods to specifically engineer the testis have an equally long and rich history, and have experienced significant progress over the past two decades, leading to current-day breakthroughs which are shifting the paradigms by which we study testicular biology and setting the stage for revolutionary new technologies to preserve and restore the fertility of human patients. The historic theme in this field is the vision of one day developing entirely ex vivo and in vitro tissue models for the study of testicular physiology and the production of in vitro derived gametes. If achieved, these new technologies might address prepubertal and azoospermic human infertility, and the lack of human research models for use in reproductive toxicology and male contraceptive development. The hypothesis for accomplishing these visions, is one shared by the biological engineering field as a whole, that biomimetic culture microenvironments are both supportive of, and instructive to, engineered tissue structure and function. This premise was tested directly in studies probing the relationship between testicular organoid self-assembly, culture microenvironment (extracellular matrix and spatial orientations), and tissue maturity. Corollary investigations into ex vivo microfluidic and static culture of human and mouse testicular explants also elucidated new perspectives towards the simulation of in vivo mimetic microenvironments for tissue culture. The combined results from this work suggest that cell maturity and state of differentiation are more important determinants of biomimetic organoid development, than the culture microenvironment. Furthermore, for explant culture, it was identified that current culture methods (static and fluidic) cannot on their own, produce a culture environment capable of preserving tissue structure or spermatogenic function but can support interstitial endocrine function. Together these organoid and explant studies demonstrate the null hypothesis of this dissertation and suggest that engineered testis structure and function is not dependent on the culture microenvironment but are innate pre-existing properties of testicular tissues and organoid-forming cells. This conclusion helps define a number of necessary ‘next-steps’ to further optimize in vitro testicular organoid development and ex vivo explant culture methods. These include identifying the responsible cell type(s) for organoid self-assembly, elucidating the genetic drivers of post-natal and in vitro testicular morphogenesis, and innovating improved methods of ex vivo tissue alteration and neovascularization for testicular tissue culture.

Creator

• Edmonds, Maxwell Ethan

DOI

• https://doi.org/10.21985/n2-ezsq-2742

Subject

• Bioengineering
• Biology
• Endocrinology

Language

• en

Alternate Identifier

• etdadmin_upload_743728
• http://dissertations.umi.com/northwestern:15119

Keyword

• testis
• model
• organoid
• reproduction
• microenvironment
• explant

Date created

• 2020-01-01

Resource type

• Dissertation

Rights statement

• In Copyright