Tailored star poly (ε-caprolactone) wet-spun scaffolds for in vivo regeneration of long bone critical size defects

One of the most challenging requirements of a successful bone tissue engineering approach is the development of scaffolds specifically tailored to individual tissue defects. Besides materials chemistry, well-defined scaffold's structural features at the micro- and macro-levels are needed for optimal bone in-growth. In this study, polymeric fibrous scaffolds with a controlled internal network of pores and modelled on the anatomical shape and dimensions of a critical size bone defect in a rabbit's radius model were developed by employing a computer-aided wet-spinning technique. The tailored scaffolds made of star poly(epsilon-caprolactone) or star poly(epsilon-caprolactone)-hydroxyapatite composite material were implanted into 20-mm segmental defects created in radial diaphysis of New Zealand white rabbits. Bone regeneration and tissue response were assessed by X-rays and histological analysis at 4, 8 and 12weeks after surgery. No signs of macroscopic and microscopic inflammatory reactions were detected, and the developed scaffolds showed a good ability to support and promote the bone regeneration process. However, no significant differences in osteoconductivity were observed between star poly(epsilon-caprolactone) and star poly(epsilon-caprolactone)-hydroxyapatite scaffolds. Long-term study on implanted star poly(epsilon-caprolactone) scaffolds confirmed the presence of signs of bone regeneration and remodelling, particularly evident at 24weeks.