In vivo prevascularization strategy enhances neovascularization of β-tricalcium phosphate scaffolds in bone regeneration

Jia Xu; Junjie Shen; YunChu Sun; Tianyi Wu; Yuxin Sun; Yimin Chai; Qinglin Kang; Biyu Rui; Gang Li

doi:10.1016/j.jot.2022.09.001

In vivo prevascularization strategy enhances neovascularization of β-tricalcium phosphate scaffolds in bone regeneration

J Orthop Translat. 2022 Oct 15:37:143-151. doi: 10.1016/j.jot.2022.09.001. eCollection 2022 Nov.

Authors

Jia Xu¹, Junjie Shen¹, YunChu Sun¹, Tianyi Wu¹, Yuxin Sun², Yimin Chai¹, Qinglin Kang¹, Biyu Rui¹, Gang Li³

Affiliations

¹ Department of Orthopedic Surgery, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, PR China.
² Department of Orthopaedics and Traumatology, Bao-An District People's Hospital, Shenzhen, PR China.
³ Department of Orthopaedics and Traumatology, Li Ka Shing Institute of Health Sciences and Lui Che Woo Institute of Innovative Medicine, Faculty of Medicine, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, PR China.

Abstract

Background: Neovascularization is critical for bone regeneration. Numerous studies have explored prevascularization preimplant strategies, ranging from calcium phosphate cement (CPC) scaffolds to co-culturing CPCs with stem cells. The aim of the present study was to evaluate an alternative in vivo prevascularization approach, using preimplant-prepared macroporous beta-tricalcium phosphate (β-TCP) scaffolds and subsequent transplantation in bone defect model.

Methods: The morphology of β-TCPs was characterized by scanning electron microscopy. After 3 weeks of prevascularization within a muscle pouch at the lateral size of rat tibia, we transplanted prevascularized macroporous β-TCPs in segmental tibia defects, using blank β-TCPs as a control. Extent of neovascularization was determined by angiography and immunohistochemical (IHC) evaluations. Tibia samples were collected at different time points for biomechanical, radiological, and histological analyses. RT-PCR and western blotting were used to evaluate angio- and osteo-specific markers.

Results: With macroporous β-TCPs, we documented more vascular and supporting tissue invasion in the macroporous β-TCPs with prior in vivo prevascularization. Radiography, biomechanical, IHC, and histological analyses revealed considerably more vascularity and bone consolidation in β-TCP scaffolds that had undergone the prevascularization step compared to the blank β-TCP scaffolds. Moreover, the prevascularization treatment remarkably upregulated mRNA and protein expression of BMP2 and vascular endothelial growth factor (VEGF) during bone regeneration.

Conclusion: This novel in vivo prevascularization strategy successfully accelerated vascular formation to bone regeneration. Our findings indicate that prevascularized tissue-engineered bone grafts have promising potential in clinical applications.

The translational potential of this article: This study indicates a novel in vivo prevascularization strategy for growing vasculature on β-TCP scaffolds to be used for repair of large segmental bone defects, might serve as a promising tissue-engineered bone grafts in the future.

Keywords: Angiogenesis; Beta-tricalcium phosphate; Bone regeneration; Prevascularization; Tissue engineering.