Antimicrobial Peptides-Loaded Hydroxyapatite Microsphere With Different Hierarchical Structures for Enhanced Drug Loading, Sustained Release and Antibacterial Activity

Immunomodulatory effects of calcium phosphate microspheres: influences of particle size on macrophage polarization and secretion patterns

This study investigated the immunomodulatory effects of calcium phosphate (CaP) microspheres, focusing on how particle size influenced macrophage polarization and cytokine secretion patterns. SEM analysis revealed that HA microspheres predominantly exhibited a spherical shape with distinct sizes and sub-micro-sized pores. The average particle sizes for the S1, S2, and S3 groups were 17.36 μm, 27.59 μm, and 47.14 μm, respectively. In vitro experiments demonstrated that small-sized S1 microspheres were more readily phagocytosed by macrophages, leading to a pro-inflammatory M1 phenotype characterized by increased gene expression of iNos and inflammatory cytokines (IL-1β, IL-6, TNF-α), and a higher proportion of CCR7+ M1 macrophages. In contrast, the larger S2 and S3 microspheres favored an anti-inflammatory M2 phenotype, with higher expression of Arg and anti-inflammatory cytokines (IL-10), and greater proportions of CD206+ M2 macrophages. Additionally, HA microspheres were injected into mouse quadriceps muscles, revealing significant differences in immune cell infiltration and tissue response. The S1 microspheres induced a prolonged and more severe inflammatory response, while the S2 and S3 microspheres were embedded in cell-rich tissue with minimal inflammation or fibrosis. It indicated the potential of larger microspheres (S2 and S3) to create a more favorable immune microenvironment that supported faster and more effective tissue healing. These findings underscore the importance of optimizing microsphere size to achieve desired immunomodulatory effects, thereby enhancing their clinical efficacy.

Emerging Bioactive Agent Delivery-Based Regenerative Therapies for Lower Genitourinary Tissues

Injury to lower genitourinary (GU) tissues, which may result in either infertility and/or organ dysfunctions, threatens the overall health of humans. Bioactive agent-based regenerative therapy is a promising therapeutic method. However, strategies for spatiotemporal delivery of bioactive agents with optimal stability, activity, and tunable delivery for effective sustained disease management are still in need and present challenges. In this review, we present the advancements of the pivotal components in delivery systems, including biomedical innovations, system fabrication methods, and loading strategies, which may improve the performance of delivery systems for better regenerative effects. We also review the most recent developments in the application of these technologies, and the potential for delivery-based regenerative therapies to treat lower GU injuries. Recent progress suggests that the use of advanced strategies have not only made it possible to develop better and more diverse functionalities, but also more precise, and smarter bioactive agent delivery systems for regenerative therapy. Their application in lower GU injury treatment has achieved certain effects in both patients with lower genitourinary injuries and/or in model animals. The continuous evolution of biomaterials and therapeutic agents, advances in three-dimensional printing, as well as emerging techniques all show a promising future for the treatment of lower GU-related disorders and dysfunctions.

Porous gelatin microsphere-based scaffolds containing MC3T3-E1 cells and calcitriol for the repair of skull defect

There is an increasing demand for biomaterials with skull regeneration for clinical application. However, most of the current skull repair materials still have limitations, such as inadequate sources, poor cell adherence, differentiation, tissue infiltration, and foreign body sensation. Therefore, this study developed porous microsphere-based scaffolds containing mouse embryonic osteoblast precursor cells (MC3T3-E1 cells) and calcitriol (Cal) using gelatin and gelatin/hydroxyapatite through green freeze-crosslinking and freeze-drying. Gelatin was employed to prepare porous microspheres with a particle size of 100-300 μm, containing open pores of 2-70 μm and interconnected paths. Furthermore, the addition of Cal to porous gelatin microsphere-based scaffolds containing MC3T3-E1 cells (PGMSs-MC) and porous gelatin/hydroxyapatite composite microspheres containing MC3T3-E1 cells (HPGMSs-MC) improved their osteoinductivity and cell proliferation and promoted the formation of mature and well-organized bone. The developed Cal-HPGMSs-MC and Cal-PGMSs-MC displayed a good porous structure and cytocompatibility, histocompatibility, osteoconductivity, and osteoinduction. Thus, the designed scaffolds provide a promising prospect for tissue-engineered constructs with skull growth and integration, laying a foundation for further research on the reconstruction of skull defects.