3D-printed hydrogel scaffold-loaded granulocyte colony-stimulating factor sustained-release microspheres and their effect on endometrial regeneration.

After injury, the endometrium cannot self-repair or regenerate because damage to the uterine basal layer often leads to intrauterine adhesions (IUAs), which can cause serious problems such as infertility and recurrent miscarriage. At present, no clinically effective method is available for the treatment of IUAs. With its advantages of being individualized and precise, three-dimensional (3D) bioprinting technology has been used to regenerate various damaged tissues and organs. Granulate colony-stimulating factor (G-CSF) clearly plays a positive role in endometrial regeneration, but precise and individualized drug applications are a prerequisite for improving the therapeutic effect of G-CSF. This study utilized a 3D-printed hydrogel in combination with a sustained-release microsphere (SRM) system to prepare a 3D-printed G-CSF-SRM system (3D microsphere) in vitro. The system advantageously allowed the spatial control of drug distribution and structural individualization. In addition to being long-acting and having a sustained release, the 3D microspheres increased the local concentration of G-CSF. Using a Sprague-Dawley rat IUA model, we confirmed that the 3D microspheres promoted local endometrial regeneration, significantly suppressed endometrium tissue fibrosis, and improved endometrial cell (epithelial and stromal cell) and vascular regeneration. The 3D microspheres significantly improved the endometrial receptivity and restored the pregnancy function of the damaged endometrium. We believe that the 3D-printed G-CSF-SRM hydrogel scaffold design concept may be used to develop a more precise and individualized treatment method for the structural and functional repair of damaged endometrial tissues.

Comparing the Characteristics of Amniotic Membrane-, Endometrium-, and Urinary-Derived ECMs and Their Effects on Endometrial Regeneration in a Rat Uterine Injury Model.

The decellularized extracellular matrices (d-ECMs) currently utilized to repair endometrial injuries are derived from three tissue sources, the endometrium (dE-ECM), placental amniotic membrane (dA-ECM), and urinary (dU-ECM). Notably, the structures of dU-ECM and dE-ECM are similar. These d-ECMs are derived from different tissues, and their specific roles in endometrial injury repair remain unclear. This study aimed to analyse the characteristics of the tissue microstructures and compositions to confirm specific differences among the three ECM types. And using a rat model of endometrial injury, the effects of all the matrices after implantation in vivo on the promotion of endometrial regeneration were analysed. After decellularization, dE-ECM had more residual active factors than the other two ECM types, while dA-ECM had significantly less DNA, α-Gal antigen components and extracellular matrix components than the other two groups. Although the three ECMs had no effect on the proliferation of stromal cells in vitro, dA-ECM may have increased the sensitivity of stromal cells to oestradiol (E2) responses. In vivo experiments confirmed the promotional effect of dA-ECM on endometrial regeneration. For example, the endometrial thickness, collagen deposition, endometrial tissue regeneration, vascular regeneration and pregnancy outcomes were significantly better in this group than in the other two groups. These findings might be associated with the excellent immune tolerance of dA-ECM. Therefore, when selecting a d-ECM for the treatment of endometrial injury, dE-ECM, which has the strongest tissue specificity, is not the preferred choice. Controlling the inflammatory responses in local lesions at the early stage may be a prerequisite for ECMs to exert their functions.

3D Bioprinting a human iPSC-derived MSC-loaded scaffold for repair of the uterine endometrium.

Common events in the clinic, such as uterine curettage or inflammation, may lead to irreversible endometrial damage, often resulting in infertility in women of childbearing age. Currently, tissue engineering has the potential to achieve tissue manipulation, regeneration, and growth, but personalization and precision remain challenges. The application of "3D cell printing" is more in line with the clinical requirements of tissue repair. In this study, a porous grid-type human induced pluripotent stem cell-derived mesenchymal stem cell (hiMSC)-loaded hydrogel scaffold was constructed using a 3D bioprinting device. The 3D-printed hydrogel scaffold provided a permissive in vitro living environment for hiMSCs and significantly increased the survival duration of transplanted hiMSCs when compared with hiMSCs administered locally in vivo. Using an endometrial injury model, we found that hiMSC transplantation can cause early host immune responses (the serological immune response continued for more than 1 month, and the local immune response continued for approximately 1 week). Compared with the sham group, although the regenerative endometrium failed to show full restoration of the normal structure and function of the lining, implantation of the 3D-printed hiMSC-loaded scaffold not only promoted the recovery of the endometrial histomorphology (endometrial tissue and gland regeneration) and the regeneration of endometrial cells (stromal cells and epithelial cells) and endothelial cells but also improved endometrial receptivity functional indicators, namely, pinopode formation and leukemia inhibitory factor and αvß3 expression, which partly restored the embryo implantation and pregnancy maintenance functions of the injured endometrium. These indicators were significantly better in the 3D-printed hiMSC-loaded scaffold group than in the unrepaired (empty) group, the hiMSCs alone group and the 3D scaffold group, and the empty group showed the worst repair results. Our study confirm that the 3D-printed hiMSC-loaded hydrogel scaffold may be a promising material for endometrial repair.