The role of biomaterials in ovarian tissue cryopreservation and transplantation: a scoping review.

Fertility preservation for women undergoing gonadotoxic treatments remains a critical clinical challenge. Ovarian tissue(OT) cryopreservation and transplantation are promising strategies. This review aims to map the biomaterials used in OT culture and cryopreservation, identify key knowledge gaps, and outline future research directions. Following the Arksey&O'Malley (2005) framework and the PRISMA-ScR guidelines, a literature search was conducted on PubMed and Web of Science. The review protocol was prospectively registered on the Open Science Framework (OSF.IO/NRZM7). Of 3,217 studies, 41 were included in the analysis: 32 were in vivo studies, 8 were in vitro, and 1 was clinical. The main biomaterials used for OT culture and cryopreservation included fibrin, alginate, collagen, hyaluronic acid, and extracellular matrix. Key preservation strategies involve encapsulating OT within biomaterial-based systems and enriching culture media with biomaterials. Hydrogels have demonstrated advantages by providing structural scaffolding and facilitating the diffusion of oxygen, nutrients, and bioactive supplements, thereby promoting angiogenesis and supporting OT functional restoration. Growing interest was noted in combinatorial approaches that integrate multiple biomaterials with stem cells, plasma proteins, and growth or antioxidant factors to enhance folliculogenesis and restore oestrous cycles. Despite progress, critical challenges persist, including capsule disintegration and the associated risk of immune sensitisation, as well as limited understanding of long-term tissue revascularisation and OT-biomaterial interactions. Overall, biobased materials strategies, particularly hydrogels, show promise for improving OT preservation and functionality, but further research is needed to optimise these materials and understand their long-term implications for fertility outcomes. Among the included studies, only one was a clinical study; the rest consisted of in vivo animal models and in vitro experiments. This limitation should be recognised, as it prevents direct application of the results to clinical practice. Consequently, further clinical research is crucial to confirm these strategies and facilitate their safe and effective implementation in fertility preservation protocols.