Engineering an immuno-isolating hydrogel for restoring ovarian endocrine function

University Of Michigan At Ann Arbor, Ann Arbor MI

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Abstract

Project Summary Premature ovarian failure (POF) is a common complication of anticancer treatments due to extreme toxicity of chemotherapy and bone marrow transplantation. In female cancer survivors POF causes sterility, along with the consequences of absent ovarian endocrine function: premature osteopenia and muscle wasting, and accelerated cardiovascular diseases. These long lasting effects are significant, particularly for young girls reaching puberty. The overall goal of the proposal is to develop means to restore ovarian endocrine function in young women with POF by utilizing allogeneic transplantation of ovarian tissue. We will engineer an advanced synthetic hydrogel carrier with spatially controlled degradation to provide a dynamic environment to support prolonged survival and function of the allogeneic ovarian transplant. First, we will investigate how the physical properties of the hydrogel, such as stiffness, degradation rate and pore size affect tissue survival and physiological function and longevity. We will design a dual hydrogel system, with a degradable core to support follicle growth and function, and non-degradable immune-isolating shell. The shell will prevent the infiltration of the immune cells into the graft and leaking of the implanted cells from the graft. Second, we will investigate how graft size and composition (the balance between stromal cells, and early and late stage follicles) determines graft longevity. Ovarian follicles have an ?expiration date? and degenerate after one cycle, thus the initial number of the follicles in the graft sets up the maximum longevity of the graft. Other factors, like hypoxia and stiff environment, can limit the function of the graft. We will determine the optimal size and composition of the follicular pool that maximize graft longevity and function a syngeneic mouse model. Lastly, we will determine whether immunity against the graft limits graft function. We will investigate the mechanism and the timeline of the ovarian graft rejection and answer two questions: 1) is the recipient sensitized to the allogeneic tissue encapsulated in the hydrogel and 2) whether T cells infiltrate through the protective layer around the graft and destroy the tissue. With respect to outcomes, this project will engineer an immunoisolating system for allotransplantation of the ovarian tissue and will present a real clinical opportunity to initiate normal puberty in young women with POF. 1