The development of collagen based composite scaffolds for bone regeneration

Abstract

Bone is consisted of bone matrix, cells and bioactive factors, and bone matrix is the combination of inorganic minerals and organic polymers. Type I collagen fibril made of five triple-helical collagen chains is the main organic polymer in bone matrix. It plays an important role in the bone formation and remodeling process. Moreover, collagen is one of the most commonly used scaffold materials for bone tissue engineering due to its excellent biocompatibility and biodegradability. However, the low mechanical strength and osteoinductivity of collagen limit its wider applications in bone regeneration field. By incorporating different biomaterials, the properties such as porosity, structural stability, osteoinductivity, osteogenicity of collagen matrixes can be largely improved. This review summarizes and categorizes different kinds of biomaterials including bioceramic, carbon and polymer materials used as components to fabricate collagen based composite scaffolds for bone regeneration. Moreover, the possible directions of future research and development in this field are also proposed.

Keywords: Biomaterials; Bone regeneration; Collagen; Composite scaffolds; Tissue engineering.

Graphical abstract

Fig. 1

(a) SEM imaging of the bilayer scaffold. (b) H&E staining pictures within the implanted scaffolds at weeks 4. The dotted white line indicates the interface between scaffold layers. The upper half is the pure collagen layer and the bottom half is the collagen/Mg-HA layer .

Fig. 2

X-ray pictures of the bone healing process of rabbit distal femoral condyles after surgery. (a) Treated with Cerasorb Ortho Foam. (b) The control group with an empty defect. The red circle indicates drilled holes. Scale bars equal to 1 mm .

Fig. 3

Fluorescence microscopy images of the bone defect of SD rats after implantation. (a, b): 4 weeks, (c, d): 8 weeks. At week 4, newly formed woven bone had been found beside CM scaffold while no newly formed bone was found in COL scaffold. Larger amount of newly formed bone can be observed in CM scaffold than that in COL scaffold. TC: tetracycline, XO: xylenol orange. WB: woven bone. BT: bone tissue, FT: fibrous tissue .

Fig. 4

A schematic illustrating the covalent conjugation of the carboxyl groups of GO flakes to the amine groups of the collagen scaffolds.

Fig. 5

a) Cranial defects with 14 mm in diameter were created in the parietal bones by a hand powered trephine. Initial defect before implantation (top) and 12 weeks after implantation of nanoparticulate mineralized collagen/GAG scaffolds (bottom) cranial defects are shown. b) Representative three-dimensional reconstructions of the CT scans of two kinds of scaffold with cross sections are shown .