Sinko, D. S. | Search bioRxiv

bioRxiv2026

Microporous Immune-Isolating Capsule with Improved Diffusion for Restored Dynamic Bidirectional Hormone Signaling in a Murine Model of Premature Ovarian Insufficiency

Pediatric cancer survivors treated with gonadotoxic chemotherapy or radiation face lifelong premature ovarian insufficiency (POI), leading to elevated risk of cardiovascular disease, osteoporosis, and metabolic dysfunction. Pharmacological hormone replacement therapy (HRT) cannot replicate the pulsatile, bidirectional signaling of the hypothalamic-pituitary-gonadal (HPG) axis, leaving a critical therapeutic gap. Immune-isolating hydrogel capsules offer a promising strategy for the implantation of donor ovarian tissue without immunosuppression yet they require optimization for human applications. Here, we engineer a microporous immune-isolating capsule by incorporating thermosensitive gelatin microgels as sacrificial porogens. Microfluidic fabrication yielded monodisperse microgels that dissolved at 37{degrees}C generating disconnected micropores within a non-degradable poly(ethylene glycol) (PEG) matrix. Critically, the diffusion of FSH-scale analogs (40 kDa) increased by almost two-fold through the microporous capsules relative to nanoporous controls, while antibody-scale molecules (150 kDa) were blocked, demonstrating size-discriminating permeability. In ovariectomized mice implanted with encapsulated ovarian xenografts for 20 weeks, microporous capsules restored dynamic HPG-axis signaling evidenced by elevated levels of estradiol and progesterone, FSH suppression, and fluctuating hormone levels that resembled physiological patterns. Microporosity also improved graft viability, increasing stromal cellularity and reducing follicular apoptosis. These findings support microporous immune-isolating capsules as a platform for physiologically authentic therapy for POI.

bioengineering↗

bioRxiv2025

MAP hydrogel promotes revascularization of human ovarian graft and integration with the hypothalamic-pituitary axis in a mouse model of primary ovarian insufficiency

Ovarian tissue cryopreservation and autotransplantation (OTCT) is a crucial fertility preservation strategy for patients facing gonadotoxic cancer treatments, but its clinical success is hampered by ischemic injury and follicle loss following transplantation. This study aimed to enhance OTCT outcomes by employing microporous annealed particle (MAP) hydrogels to promote human ovarian graft revascularization. Unlike non-encapsulated tissue grafts, which exhibited early but transient and disorganized host vascular infiltration followed by regression, tissue grafts encapsulated in MAP hydrogels (OvaMAPs) demonstrated delayed yet organized and stable, long-term revascularization. OvaMAPs had significantly greater mouse CD31+ tissue area and vessel length after 3 and 6 weeks post-transplantation in ovariectomized immunodeficient mice compared to non-encapsulated grafts. By 20 weeks, both groups restored physiological estradiol levels (with OvaMAPs reaching 158 pg/mL) and suppressed follicle-stimulating hormone, confirming integration of the grafts with the hosts hypothalamic-pituitary axes. Notably, OvaMAPs achieved comparable endocrine function restoration with reduced estradiol variability, indicating more consistent graft function. In conclusion, MAP hydrogel encapsulation promoted long-term graft revascularization and vascular stability after OTCT, ultimately supporting consistent endocrine integration with host physiology.

bioengineering↗