Biomimetic biphasic scaffolds for osteochondral defect repair

Abstract

The osteochondral defects caused by vigorous trauma or physical disease are difficult to be managed. Tissue engineering provides a possible option to regenerate the damaged osteochondral tissues. For osteochondral reconstruction, one intact scaffold should be considered to support the regeneration of both cartilage and subchondral bone. Therefore, the biphasic scaffolds with the mimic structures of osteochondral tissues have been developed to close this chasm. A variety of biomimetic bilayer scaffolds fabricated from natural or synthetic polymers, or the ones loading with growth factors, cells, or both of them make great progresses in osteochondral defect repair. In this review, the preparation and in vitro and/or in vivo verification of bioinspired biphasic scaffolds are summarized and discussed, as well as the prospect is predicted.

Keywords: biomaterial; biomimetic; biphasic scaffold; osteochondral regeneration; tissue engineering.

Figure 1.

Classification of articular cartilage defects. Osteochondral defects characterize of the damage extending deep into the subchondral bone. (Reprinted with permission from Ref. [4])

Figure 2.

Typical histological structure of osteochondral unit (A). Typical scanning electron microscope (SEM) cross-section microimage of integrated bi-layered poly(2-hydroxyethyl methacrylate (PHEMA)/HA//PHEMA/HAp scaffold (B). (Reprinted with permission from Refs. [5, 32])

Figure 3.

Schematic illustration of integration of chondral phase and osseous part via stereolithography (A). Fabricated ceramic scaffold (Left) and PEG/β-TCP scaffold (Right; B). The cured PEG hydrogel is tightly anchored to the underlying ceramic substrate. Illustration of scaffold implantation in rabbit trochlea osteochondral defects (C and D). Gross appearance of repaired cartilage (E), 3D model of repaired subchondral bone (F), and histology of repaired cartilage (G) after implantation of PEG/β-TCP scaffold for 52 weeks. (Reprinted with permission from Refs. [34, 57])

Figure 4.

Diagrammatic representation of construction procedure of bilayer gene-activated composite osteochondral graft along with MSCs loaded into TGF-β1-activated CG scaffold layer and BMP-2-activated HCG scaffold layer (A). Macroscopic observation (B), H&E staining (C), and immunohistochemical staining of Col II (D) and Col I (E) of bilayer gene-activated osteochondral graft after 2 weeks of culture in vitro (× 200). Macrophotography of osteochondral defect repair in vivo (F), histological analysis by H&E staining (G), immunohistochemical staining of Col II (H), and immunohistochemical staining of Col I and Alcian blue staining for hyaline cartilage (I) after implanting bilayer gene-activated composite osteochondral scaffold incubated for 2 weeks in vitro for 12 weeks. (Reprinted with permission from Ref. [44])