Recent Approaches to the Manufacturing of Biomimetic Multi-Phasic Scaffolds for Osteochondral Regeneration

Abstract

Cartilage lesions of the knee are common disorders affecting people of all ages; as the lesion progresses, it extends to the underlying subchondral bone and an osteochondral defect appears. Osteochondral (OC) tissue compromises soft cartilage over hard subchondral bone with a calcified cartilage interface between these two tissues. Osteochondral defects can be caused by numerous factors such as trauma and arthritis. Tissue engineering offers the possibility of a sustainable and effective treatment against osteochondral defects, where the damaged tissue is replaced with a long-lasting bio-manufactured replacement tissue. This review evaluates both bi-phasic and multi-phasic scaffold-based approaches of osteochondral tissue regeneration, highlighting the importance of having an interface layer between the bone and cartilage layer. The significance of a biomimetic approach is also evidenced and shown to be more effective than the more homogenous design approach to osteochondral scaffold design. Recent scaffold materials and manufacturing techniques are reviewed as well as the current clinical progress with osteochondral regeneration scaffolds.

Keywords: bi-phasic; biomimetic; multi-phasic; osteochondral regeneration; scaffold.

Figure 1

Schematic of osteochondral tissue and its components. Adapted with permission from ref [4]. Copyright 2015 by John Wiley & Sons, Inc.

Figure 2

Gross appearance of the knees after implantation in vivo at 6 and 12 weeks. (a) At 6 weeks in group A; (b) At 6 weeks in group B; (c) At 6 weeks in group C; (d) At 12 weeks in group A; (e) At 12 weeks in group B; (f) At 12 weeks in group C. Adapted with permission from ref [32]. Copyright 2015 by John Wiley & Sons, Inc.

Figure 3

Scheme of the preparation of the conically graded chitosan-gelatin hydrogel/poly(lactide-co-glycolide) (PLGA) scaffold. Adapted with permission from ref [38]. Copyright 2014 by John Wiley & Sons, Inc.

Figure 4

Schematic of articular cartilage anatomy which illustrates how the GAG content, collagen X and compressive modulus increase from the superficial to the deep zones of articular cartilage. Collagen II is also shown too decrease in content from the superficial to the deep zones of articular cartilage. Adapted with permission from ref [41]. Copyright 2011 by Elsevier, Inc.

Figure 5

Diagram of the lyophilisation process used to fabricate the final osteochondral scaffold. Scaffold contains superficial (SZ), transition (TZ), calcified cartilage (CCZ), and osseous zones (OZ). Adapted with permission from ref [42]. Copyright 2011 by John Wiley & Sons, Inc.