A review of fibrin and fibrin composites for bone tissue engineering

Abstract

Tissue engineering has emerged as a new treatment approach for bone repair and regeneration seeking to address limitations associated with current therapies, such as autologous bone grafting. While many bone tissue engineering approaches have traditionally focused on synthetic materials (such as polymers or hydrogels), there has been a lot of excitement surrounding the use of natural materials due to their biologically inspired properties. Fibrin is a natural scaffold formed following tissue injury that initiates hemostasis and provides the initial matrix useful for cell adhesion, migration, proliferation, and differentiation. Fibrin has captured the interest of bone tissue engineers due to its excellent biocompatibility, controllable biodegradability, and ability to deliver cells and biomolecules. Fibrin is particularly appealing because its precursors, fibrinogen, and thrombin, which can be derived from the patient's own blood, enable the fabrication of completely autologous scaffolds. In this article, we highlight the unique properties of fibrin as a scaffolding material to treat bone defects. Moreover, we emphasize its role in bone tissue engineering nanocomposites where approaches further emulate the natural nanostructured features of bone when using fibrin and other nanomaterials. We also review the preparation methods of fibrin glue and then discuss a wide range of fibrin applications in bone tissue engineering. These include the delivery of cells and/or biomolecules to a defect site, distributing cells, and/or growth factors throughout other pre-formed scaffolds and enhancing the physical as well as biological properties of other biomaterials. Thoughts on the future direction of fibrin research for bone tissue engineering are also presented. In the future, the development of fibrin precursors as recombinant proteins will solve problems associated with using multiple or single-donor fibrin glue, and the combination of nanomaterials that allow for the incorporation of biomolecules with fibrin will significantly improve the efficacy of fibrin for numerous bone tissue engineering applications.

Keywords: bone repair; fibrin; fibrin beads; fibrin coating; fibrin preparation; fibrinogen; injectable hydrogel; nanofibrous scaffold.

Figure 1

Fibrinogen structure. Aα chains are shown in blue, Bβ chains are shown in green, and γ chains are shown in red. Disulfide bridges stabilizing the coiled-coil regions are shown in yellow.

Figure 2

Scanning electron micrograph of 1 mg/L human fibrinogen polymerized by 1 U/mL thrombin at pH 7.4 and 150 mM NaCl. Full width of the figure is 62.5 mm. Janmey PA, Winer JP, Weisel JW. Fibrin gels and their clinical and bioengineering applications. J R Soc Interface. 2009;6(30):1–10, by permission of The Royal Society.

Figure 3

AFM images of a control fibrin gel (A) and a strained fibrin gel (B). Scanning electron microscopy images of a control fibrin gel (C) (bar: 1 µm) and bundle-like structures formed in a strained fibrin gel (D) (bar: 5 µm). Reproduced from Matsumoto T, Sasaki J-I, Alsberg E, Egusa H, Yatani H, Sohmura T. Three-dimensional cell and tissue patterning in a strained fibrin gel system. PLoS One. 2007;2(11):e1211. Mineral depositions of contained mouse BMSCs detected by von Kossa staining of a control gel (E) and strained gel (F) (bar: 50 µm). Reproduced from with permission of The Royal Society of Chemistry. H&E stained images of ectopic bone formation by nonstatic (G) and static (H) fibrin gels. Implanted fibrin gels were harvested at 6 weeks after implantation in mice (bar: 50 µm). Reproduced from Sasaki JI, Matsumoto T, Imazato S. Oriented bone formation using biomimetic fibrin hydrogels with three-dimensional patterned bone matrices. J Biomed Mater Res A. 2015;103(2):622–627. The arrows indicate the mechanical force direction. Abbreviations: AFM, atomic force microscopy; BMSCs, bone marrow-derived stromal cells; H&E, hematoxylin and eosin.

Figure 4

Different methods used to isolate fibrinogen from plasma. Abbreviations: EtOH, ethanol; PEG, poly(ethylene glycol); SDS-PAGE, sodium dodecyl sulfate polyacrylamide gel electrophoresis; TBS, Tris-buffered saline.

Figure 5

Confocal microscopic images of actin-stained hMSCs on (A) control Ti and (B) modified Ti after 6 h of incubation. The interpenetrating network of fibrin alginate scaffolds can be clearly seen on the modified Ti plate with the cells exhibiting a well spread morphology with a highly organized actin cytoskeletal arrangement than for the control plate. Reproduced from Soumya S, Sreerekha P, Menon D, Nair SV, Chennazhi KP. Generation of a biomimetic 3D microporous nano-fibrous scaffold on titanium surfaces for better osteointegration of orthopedic implants. J Mater Chem. 2012;22(5):1904–1915 with permission of The Royal Society of Chemistry. Abbreviation: hMSC, human mesenchymal stem cell.

Figure 6

Live/dead fluorescence imaging of MG-63 cells cultured on collagen sponges (COL-S), COL-S/fibrinogen (FNG) 10, COL-S/FNG 40, and COL-S/FNG 80 scaffolds in normal growth media. The viability/cytotoxicity assay was performed after 5 days of culture. Live and healthy cells were stained green by calcein acetoxymethyl (Calcein AM), and dead cells were stained red by ethidium homodimer-1 (EthD-1). Copyright © John Wiley and Sons. Reproduced from Kim BS, Kim JS, Lee J. Improvements of osteoblast adhesion, proliferation, and differentiation in vitro via fibrin network formation in collagen sponge scaffold. J Biomed Mater Res A. 2013;101(9):2661–2666.

Figure 7

(A) Gross examination and soft X-ray examination of the fibrin gel group, fibrin gel apatite-coated PLGA/HA particulate group, BMP-2-loaded fibrin gel group, and BMP-2-loaded apatite-coated PLGA/HA particulates suspended in a fibrin gel group at 8 weeks after implantation into critical-sized calvarial defects of rats. (B) Radiological defect healing at 8 weeks. Reproduced from Kim SS, Gwak SJ, Kim BS. Orthotopic bone formation by implantation of apatite-coated poly (lactide-co-glycolide)/hydroxyapatite composite particulates and bone morphogenetic protein-2. J Biomed Mater Res A. 2008;87(1):245–253. Abbreviations: PLGA, poly(lactic-co-glycolic acid); HA, hydroxyapatite; BMP-2, bone morphogenetic protein 2; HAp, hydroxylapatite particulates.

Figure 8

Schematic representation of the electrospinning of PCL fibrin multiscale nanoscaffolds. The arrows indicate steps that are repeated sequentially to obtain a composite scaffold. Abbreviations: DC, direct current; PCL, poly caprolactone.