Adsorbed fibrinogen leads to improved bone regeneration and correlates with differences in the systemic immune response
2013
Santos, S.G. | Lamghari, M. | Almeida, C.R. | Oliveira, M.I. | Neves, N. | Ribeiro, A.C. | Barbosa, J.N. | Barros, R. | Maciel, J. | Martins, M.C.L. | Gonçalves, R.M. | Barbosa, M.A.
Designing new biomaterials that can modulate the inflammatory response instead of attempting just to reduce it constitutes a paradigm change in regenerative medicine. This work aimed to investigate the capacity of an immunomodulatory biomaterial to enhance bone regeneration. For that purpose we incorporated a molecule with well-established pro-inflammatory and pro-healing roles, fibrinogen, in chitosan scaffolds. Two different incorporation strategies were tested, leading to concentrations of 0.54±0.10mg fibrinogen g⁻¹ scaffold immediately upon adsorption (Fg-Sol), and 0.34±0.04mg fibrinogen g⁻¹ scaffold after washing (Fg-Ads). These materials were implanted in a critical size bone defect in rats. At two months post-implantation the extent of bone regeneration was examined by histology and the systemic immune response triggered was evaluated by determining the percentages of myeloid cells, T and B lymphocytes in the draining lymph nodes. The results obtained indicate that the fibrinogen incorporation strategy conditioned the osteogenic capacity of biomaterials. Fg-Ads scaffolds led to more bone formation, and the presence of Fg stimulated angiogenesis. Furthermore, animals implanted with Fg-Ads scaffolds showed significant increases in the percentages of B lymphocytes and myeloid cells in the draining lymph nodes, while levels of T lymphocytes were not significantly different. Finally, a significant increase in TGF-β1 was detected in the plasma of animals implanted with Fg-Ads. Taken together the results presented suggest a potential correlation between the elicited immune response and biomaterial osteogenic performance.
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