Antioxidant nanozyme microneedles with stem cell loading for in situ endometrial repair

Endometrial injury could result in infertility as well as recurrent miscarriage in women of reproductive age. Stem cells are valuable for the treatment of the endometrial injury; while their effective transplantations and functions displaying are still challenges. Herein, we present novel antioxidant cerium oxide (CeO2) nanozyme microneedles with stem cell loading for in situ endometrial repair. The MNs were made of gelatin methacryloyl (GelMA) with nanozyme and stem cells in the backing layer and tips, respectively, imparting the MNs with distinctive features including antioxidant activity, high cell viability, and rapid degradation. With the MN patch, the damaged endometrium shows the well-defined regeneration of smooth muscle and neovascularization. Notably, embryos can be implanted in the regenerated sites and stay alive to the late pregnancy stage, indicating that the hybrid microneedles not only promote the morphological reconstruction of injured uterus, but also increase the pregnancy rate and restore the reproductive function. These features indicated that the flexible multifunctional biohybrid MNs could serve as an ideal candidate for versatile in situ tissue repair and regeneration.