Bioactive Membrane Immobilized with Lactoferrin for Modulation of Bone Regeneration and Inflammation

Guided bone regeneration refers to the process in which bone defects could be regenerated by facilitated healing through the use of membranes, potentially with the delivery of osteoinductive molecules, however, the regeneration often failed due to inflammation during bone formation. In this study, we developed a membrane immobilized with lactoferrin to modulate both bone regeneration and inflammatory responses. Lactoferrin was immobilized on electrospun nanofibers (LF50) by exploiting an adhesive polydopamine coating method. When human adipose-derived stem cells (hADSCs) were seeded onto the nanofibers, the LF50 significantly increased the osteogenic differentiation. For example, the gene expression of osteopontin was 6.9 +/- 2.3 times greater in the cells on LF50 than the cells on unmodified nanofibers without lactoferrin. In addition, the gene expression of tumor necrosis factor-alpha (TNF-alpha) of the macrophage cell line (RAW264.7) cultured on the LF50 was 0.3 +/- 0.1 times reduced, indicating the lactoferrin was able to reduce inflammatory response. With implantation of nanofibers on in vivo mouse calvarial defects, the LF50 resulted in 60.9% +/- 4.5% of new bone formation, which was six times greater than the results of other groups. Furthermore, when the fibers were implanted onto the in vivo mouse subcutaneous model challenged with lipopolysaccharide and interferon-gamma, the area of inflammatory tissue was significantly reduced in the LF50 implanted group as 0.6 +/- 0.1 mm(2) as compared with the control group (1.1 +/- 0.1 mm(2)). Taken together, the lactoferrin immobilization onto the nanofiber by polydopamine chemistry may be an effective delivery method for improving bone regeneration while regulating the inflammation. Impact statement In vivo critical-sized bone reconstruction remains challenging due to the severe inflammation, which would be an unavoidable problem during surgical process. Therefore, the present study aims to develop a guided nanofibrous membrane immobilized with lactoferrin, which has dual functions with osteoinduction and anti-inflammation. The lactoferrin-immobilized fibers demonstrated significantly enhanced in vitro osteogenic differentiation of adipose-derived stem cells as well as decreased polarization of macrophage to M1 with relatively reduced amount than that reported from previous reports. We also found that the membrane improved in vivo bone regeneration and decreased inflammatory tissue formation. Taken together, this system would be a new platform for successful bone regeneration.