3D-Printed DOX-LF-Loaded PLGA Biphasic Composite Scaffold Modulates Macrophage Polarization and Enhances Osteogenic-Angiogenic Regenerative Potential for Periodontitis

Background: To develop an immunomodulatory scaffold integrating antibacterial activity with osteogenic–angiogenic coupling for inflammatory periodontal repair. Methods: A biphasic poly(lactic-co-glycolic acid) (PLGA) scaffold incorporating doxycycline-lactoferrin (DOX-LF)-loaded calcium alginate microspheres and fibroblast growth factor 2/bone morphogenetic protein 9 (FGF2/BMP9)-loaded chitosan nanospheres was fabricated by low-temperature three-dimensional (3D) printing, porogen leaching, and freeze-drying. Material properties, antibacterial activity, macrophage polarization, periodontal ligament stem cell (PDLSC) osteogenesis, and human umbilical vein endothelial cell (HUVEC) angiogenesis were evaluated. Small interfering RNA (siRNA)-mediated milk fat globule-epidermal growth factor 8 (MFGE8) knockdown was used to investigate the underlying mechanism. Results: The scaffold formed an interconnected porous network and released approximately 88.4% of DOX and 60% of LF over 240 h. PLGA/DOX-LF reduced Porphyromonas gingivalis viability to approximately 20% (p < 0.001). In lipopolysaccharide (LPS)-stimulated macrophages, it produced the greatest suppression of M1-associated markers and induction of M2-associated markers, while MFGE8 knockdown significantly reduced MFGE8 expression (p < 0.001) and attenuated these effects. Conditioned medium restored PDLSC migration, ALP activity, and mineralization to approximately 70%, 70–75%, and 80% of control levels, respectively, and increased HUVEC tube length (p < 0.01) and angiogenic gene expression (all p < 0.001). Conclusions: A 3D-printed biphasic PLGA scaffold incorporating DOX-LF-loaded calcium alginate microspheres and FGF2/BMP9-loaded chitosan nanospheres was successfully constructed. These in vitro findings support PLGA/DOX-LF as a proof-of-concept platform for antibacterial immunomodulation and osteogenic–angiogenic coupling, pending in vivo validation.