PROJECT SUMMARY/ABSTRACT
Ovarian tissue cryopreservation (OTC), a fertility preservation option for cancer patients and others at increased
risk of developing infertility that is ideally performed prior to the gonadotoxic treatment, has enabled >140 live
births. However, fertility restoration is currently limited to transplantation of OTC tissue, and some patients may
not be able to use this option due to the risk of reintroducing their disease. An alternative that is not yet developed
for the clinic, would be to use the primordial follicles, the oocyte and support cell units that are cryopreserved in
OTC, and perform in vitro growth and maturation (IVGM) to produce eggs. Current assisted reproductive
technologies require 20 – 30 eggs to offer a good chance of producing a child. However, current IVGM protocols
performed in the research lab are not efficient and yield only a few eggs for every 10 or more patients.
Importantly, the success of current methods for isolating primordial follicles from ovarian tissue drastically differs
between patients and, at best, only a small percentage are obtained intact. Secondary follicles more easily
remain intact, but few are cryopreserved during OTC. Therefore, primordial follicles must be activated to grow to
secondary follicles if OTC tissue is used to make eggs. The rate limiting steps for advancing IVGM are: (1)
efficiently and reliably isolating healthy primordial follicles that are activated to grow, and (2) efficiently and
reliably growing and maturing secondary follicles into good quality eggs. 3D-printed bioscaffolds of specific
architectures can support the viability and growth of secondary follicles through egg maturation in vitro, as well
as primordial follicle growth and maturation through egg maturation, ovulation, and live birth in mice. These
promising results lay the foundation to further explore the use of specifically designed bioscaffolds to address
current limitations of IVGM. This application tests the hypothesis that a dynamic synthetic microenvironment will
provide the necessary mechanical and architectural cues to induce stromal cell migration out of ovarian tissue,
release of the embedded follicles, and support follicle growth and oocyte maturation into an egg. 3D-printed
bioscaffolds of varying mechanical and remodeling properties using tunable highly porous biomaterials will be
utilized to induce follicle migration from cortical tissue and provide a dynamic environment that remodels over
time as the follicles grow. Bovine ovaries as used to mimic human ovaries in size, cortical density, follicle growth
and maturation for the following aims: (1) to define the bioscaffolds that support stromal cell migration and
subsequent release, activation, and growth of primordial follicles; and (2) to define the bioscaffolds that induce
growth and maturation of isolated secondary follicles in vitro. These studies will identify specific properties of
synthetic microenvironments that can enhance follicle isolation from ovarian tissue, as well as those that support
the growth and maturation of follicles into eggs. If successful, this work would enable researchers to study
folliculogenesis from primordial follicle activation to an egg in a controlled environment, would uncover a
completely novel approach to IVGM and support the development of future technologies for IVGM in humans.
