Ex-vivo preservation of ovine ovarian tissue using PEGylated fibrin hydrogel: a practical biomaterial-based strategy

Can PEGylated fibrin hydrogel serve as a supportive three-dimensional scaffold to improve short-term survival of ovarian cortical tissue, which has implications for fertility preservation?

Ovine ovarian cortical fragments were encapsulated in PEGylated fibrin hydrogel, synthesized by conjugating four-arm PEG-succinimidyl glutarate with fibrinogen (10:1 ratio) and cross-linked with thrombin and CaCl₂. Encapsulated and non-encapsulated tissues were cultured for 96 h. Morphological and functional assessments included histology, Masson's trichrome staining, immunohistochemistry for caspase-3 and vascular endothelial growth factor (VEGF), immunofluorescence for CD31, and lactate dehydrogenase cytotoxicity assays.

Encapsulation significantly preserved primordial follicle density at 48 h (P = 0.01), and reduced degeneration of growing follicles at 72 h (P = 0.006). Stromal cell density was maintained in the encapsulated group at 48 h (P = 0.01), 72 h (P = 0.02) and 96 h (P = 0.001). The proportions of caspase-3-positive stromal cells and follicles were lower in encapsulated tissues at 72 h (P = 0.009 and P = 0.007, respectively), indicating that apoptosis may be reduced. Moreover, in the encapsulated group, the CD31-positive percentage area was elevated at 24 h (P = 0.05), 48 h (P < 0.0001) and 72 h (P = 0.001), whereas the proportion of VEGF-positive cells was higher at 48 h (P = 0.01) and 72 h (P = 0.05), suggesting enhanced angiogenic signalling.

PEGylated fibrin hydrogel provides short-term cryoprotection by supporting stromal and follicular viability, and stimulating angiogenesis during ex-vivo ovarian tissue culture. These findings highlight its potential as a biomimetic scaffold in ovarian tissue engineering, although further optimization is required for extended culture periods and clinical translation.