Facilitated vascularization and enhanced bone regeneration by manipulation hierarchical pore structure of scaffolds

Yang Liu; Shengbing Yang; Lingyan Cao; Xiaohui Zhang; Jing Wang; Changsheng Liu

doi:10.1016/j.msec.2019.110622

Facilitated vascularization and enhanced bone regeneration by manipulation hierarchical pore structure of scaffolds

Mater Sci Eng C Mater Biol Appl. 2020 May:110:110622. doi: 10.1016/j.msec.2019.110622. Epub 2020 Jan 7.

Authors

Yang Liu¹, Shengbing Yang², Lingyan Cao³, Xiaohui Zhang¹, Jing Wang⁴, Changsheng Liu⁵

Affiliations

¹ The State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, People's Republic of China; Engineering Research Center for Biomedical Materials of Ministry of Education, East China University of Science and Technology, Shanghai 200237, People's Republic of China.
² Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai 200011, People's Republic of China.
³ Department of Prosthodontics, Oral Bioengineering and Regenerative Medicine Lab, Shanghai Key Laboratory of Stomatology, Ninth People's Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Shanghai 200011, People's Republic of China.
⁴ The State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, People's Republic of China; Engineering Research Center for Biomedical Materials of Ministry of Education, East China University of Science and Technology, Shanghai 200237, People's Republic of China. Electronic address: biomatwj@163.com.
⁵ Engineering Research Center for Biomedical Materials of Ministry of Education, East China University of Science and Technology, Shanghai 200237, People's Republic of China; Key Laboratory for Ultrafine Materials of Ministry of Education, East China University of Science and Technology, Shanghai 200237, People's Republic of China. Electronic address: liucs@ecust.edu.cn.

PMID: 32204064
DOI: 10.1016/j.msec.2019.110622

Abstract

Sufficient vascularization is quite important for preventing cell death and promoting host integration during the repair of the critical sized bone defects. Porous structure providing enough space for the ingrowth of vessels is an essential consideration during the scaffold's development. In this study, we designed and fabricated three kinds of porous structured scaffolds based on poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx), such as mono-structured PHBHHx scaffolds with macro pores (PH-1), di-structured PHBHHx scaffolds with macro-meso pores (PHS-2), and tri-structured PHBHHx scaffolds with macro-micro-meso pores (PHS-3), respectively. In vitro effects of the hierarchical porous scaffolds on human umbilical vein endothelial cells (HUVECs), such as cell attachment, glucose and lactate detection, relative gene expressions of endothelial markers were investigated. The PHS-3 scaffolds exhibited preferential potency of inducing better angiogenesis in vitro. Consequently, the hierarchical porous scaffolds were applied to load rhBMP-2 and repair the critical sized bone defect (15 mm) in rabbits. Microangiography analysis by three dimensional micro-computed tomographic (micro-CT) demonstrated that the volume of blood vessels within the defect area was higher in the rhBMP-2 loaded PHS-3 (PHS-3/rhBMP-2) than that in other rhBMP-2 loaded porous scaffolds with simplex or double scaled pores (PH-1/rhBMP-2 or PHS-2/rhBMP-2) at 4 weeks and 8 weeks, which implied that multi-level porous structure was conducive to nutrition transmission and revascularization. Further investigations of orthotopic bone formation by micro-CT, histological and immunohistochemistry analysis confirmed the most accelerated new bone formation rate in the PHS-3/rhBMP-2 group. The maximum load value of the regenerated bone induced by PHS-3/rhBMP-2 at 12 weeks was 258.47 ± 14.77 N which did not show significant difference from the normal bone of 268.81 ± 12.05 N. These results highlighted that introducing multi-level pores into the biocompatible scaffolds may be an effective approach to promote angiogenesis and bone regeneration.

Keywords: Bone regeneration; Hierarchical structure; Scaffold; Vascularization.

MeSH terms

3-Hydroxybutyric Acid / chemistry*
Animals
Antigens, Differentiation / biosynthesis
Bone Morphogenetic Protein 2 / chemistry
Bone Regeneration*
Caproates / chemistry*
Cell Adhesion
Gene Expression Regulation*
Human Umbilical Vein Endothelial Cells
Humans
Male
Neovascularization, Physiologic*
Osteogenesis*
Porosity
Rabbits
Tissue Scaffolds / chemistry*

Substances

Antigens, Differentiation
BMP2 protein, human
Bone Morphogenetic Protein 2
Caproates
poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)
3-Hydroxybutyric Acid