Vaginal Tissue Engineering via Gelatin-Elastin Fiber-Reinforced Hydrogels.

The vagina is a fibromuscular tube-shaped organ spanning from the hymenal ring to the cervix that plays critical roles in menstruation, pregnancy, and female sexual health. Vaginal tissue constituents, including cells and extracellular matrix components, contribute to tissue structure, function, and prevention of injury. However, much microstructural function remains unknown, including how the fiber-cell and cell-cell interactions influence macromechanical properties. A deeper understanding of these interactions will provide critical information needed to reduce and prevent vaginal injuries. Our objectives for this work herein are to first engineer a suite of biomaterials for vaginal tissue engineering and second to characterize the performance of these biomaterials in the vaginal microenvironment. We successfully created fiber-reinforced hydrogels of gelatin-elastin electrospun fibers infiltrated with gelatin methacryloyl hydrogels. These composites recapitulate vaginal material properties, including stiffness, and are compatible with the vaginal microenvironment: biocompatible with primary vaginal epithelial cells and in acidic conditions. This work significantly advances progress in vaginal tissue engineering by developing novel materials and developing a state-of-the-art tissue engineered vagina.

Bioengineering approaches for patient-specific analysis of placenta structure and function.

The leading cause of perinatal mortality is fetal growth restriction (FGR), defined as in utero fetal growth below the 10th percentile. Insufficient exchange of oxygen and nutrients at the maternal-fetal interface is associated with FGR. This transport occurs through the vasculature of the placenta, particularly in the terminal villi, where the vascular membranes have a large surface area and are the thinnest. Altered structure of the placenta villi is thought to contribute to decreased oxygen exchange efficiency, however, understanding how the three-dimensional microstructure and properties decrease this efficiency remains a challenge. Here, a novel, multiscale workflow is presented to quantify patient-specific biophysical properties, 3D structural features, and blood flow of the villous tissue. Namely, nanoindentation, optical coherence tomography, and ultrasound imaging were employed to measure the time-dependent material properties of placenta tissue, the 3D structure of villous tissue, and blood flow through the villi to characterize the microvasculature of the placenta at increasing length scales. Quantifying the biophysical properties, the 3D architecture, and blood flow in the villous tissue can be used to infer changes in maternal-fetal oxygen transport at the villous membrane. Overall, this multiscale understanding will advance knowledge of how microvascular changes in the placenta ultimately lead to FGR, opening opportunities for diagnosis and intervention.

Evaluation of gelatin bloom strength on gelatin methacryloyl hydrogel properties.

Gelatin methacryloyl (GelMA) hydrogels are widely used for a variety of tissue engineering applications. The properties of gelatin can affect the mechanical properties of gelatin gels; however, the role of gelatin properties such as bloom strength on GelMA hydrogels has not yet been explored. Bloom strength is a food industry standard for describing the quality of gelatin, where higher bloom strength is associated with higher gelatin molecular weight. Here, we evaluate the role of bloom strength on GelMA hydrogel mechanical properties. We determined that both bloom strength of gelatin and weight percent of GelMA influenced both stiffness and viscoelastic ratio; however, only bloom strength affected diffusivity, permeability, and pore size. With this library of GelMA hydrogels of varying properties, we then encapsulated Swan71 trophoblast spheroids in these hydrogel variants to assess how bloom strength affects trophoblast spheroid morphology. Overall, we observed a decreasing trend of spheroid area and Feret diameter as bloom strength increased. In identifying clear relationships between bloom strength, hydrogel mechanical properties, and trophoblast spheroid morphology, we demonstrate that bloom strength should considered when designing tissue engineered constructs.

Evaluation of gelatin bloom strength on gelatin methacryloyl hydrogel properties.

Gelatin methacryloyl (GelMA) hydrogels are widely used for a variety of tissue engineering applications. The properties of gelatin can affect the mechanical properties of gelatin gels; however, the role of gelatin properties such as bloom strength on GelMA hydrogels has not yet been explored. Bloom strength is a food industry standard for describing the quality of gelatin, where higher bloom strength is associated with higher gelatin molecular weight. Here, we evaluate the role of bloom strength on GelMA hydrogel mechanical properties. We determined that both bloom strength of gelatin and weight percent of GelMA influenced both stiffness and viscoelastic ratio; however, only bloom strength affected diffusivity, permeability, and pore size. With this library of GelMA hydrogels of varying properties, we then encapsulated Swan71 trophoblast spheroids in these hydrogel variants to assess how bloom strength affects trophoblast spheroid morphology. Overall, we observed a decreasing trend of spheroid area and Feret diameter as bloom strength increased. In identifying clear relationships between bloom strength, hydrogel mechanical properties, and trophoblast spheroid morphology, we demonstrate that bloom strength should considered when designing tissue engineered constructs.