Three-dimensional bioprinting of multicell-laden scaffolds containing bone morphogenic protein-4 for promoting M2 macrophage polarization and accelerating bone defect repair in diabetes mellitus

Bioact Mater. 2020 Sep 25;6(3):757-769. doi: 10.1016/j.bioactmat.2020.08.030. eCollection 2021 Mar.

Authors

Xin Sun¹, Zhenjiang Ma¹, Xue Zhao^{2

3}, Wenjie Jin¹, Chenyu Zhang¹, Jie Ma¹, Lei Qiang^{1

4}, Wenhao Wang^{1

4}, Qian Deng^{1

4}, Han Yang⁵, Jinzhong Zhao⁶, Qianqian Liang⁷, Xiaojun Zhou⁸, Tao Li⁹, Jinwu Wang¹

Affiliations

¹ Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, No. 639 Zhizaoju Road, Shanghai, 200011, China.
² Department of Radiology, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, No. 639 Zhizaoju Road, Shanghai, 200011, China.
³ Department of Radiology, Minhang Hospital of Fudan University, Minhang Central Hospital, No. 170 Xinsong Road, Shanghai 201100, China.
⁴ Southwest JiaoTong University College of Medicine, No. 111 North 1st Section of Second Ring Road, Chengdu, 610031, China.
⁵ School of Biomedical Engineering, Shanghai JiaoTong University, No. 1956 Huashan Road, Shanghai, 200030, China.
⁶ Department of Sports Medicine, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, No. 600, Yishan Road, Shanghai 200233, China.
⁷ Spine Institute, Shanghai University of Traditional Chinese Medicine, No.1200 Cailun Road, Shanghai 200032, China.
⁸ College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, No. 2999, North Renmin Road, Shanghai 201620, China.
⁹ Department of Orthopaedics, Xinhua Hospital affiliated to Shanghai Jiaotong University School of Medicine, No.1665 Kongjiang Road, Shanghai, 200092, China.

Abstract

Critical-sized bone defect repair in patients with diabetes mellitus remains a challenge in clinical treatment because of dysfunction of macrophage polarization and the inflammatory microenvironment in the bone defect region. Three-dimensional (3D) bioprinted scaffolds loaded with live cells and bioactive factors can improve cell viability and the inflammatory microenvironment and further accelerating bone repair. Here, we used modified bioinks comprising gelatin, gelatin methacryloyl (GelMA), and 4-arm poly (ethylene glycol) acrylate (PEG) to fabricate 3D bioprinted scaffolds containing BMSCs, RAW264.7 macrophages, and BMP-4-loaded mesoporous silica nanoparticles (MSNs). Addition of MSNs effectively improved the mechanical strength of GelMA/gelatin/PEG scaffolds. Moreover, MSNs sustainably released BMP-4 for long-term effectiveness. In 3D bioprinted scaffolds, BMP-4 promoted the polarization of RAW264.7 to M2 macrophages, which secrete anti-inflammatory factors and thereby reduce the levels of pro-inflammatory factors. BMP-4 released from MSNs and BMP-2 secreted from M2 macrophages collectively stimulated the osteogenic differentiation of BMSCs in the 3D bioprinted scaffolds. Furthermore, in calvarial critical-size defect models of diabetic rats, 3D bioprinted scaffolds loaded with MSNs/BMP-4 induced M2 macrophage polarization and improved the inflammatory microenvironment. And 3D bioprinted scaffolds with MSNs/BMP-4, BMSCs, and RAW264.7 cells significantly accelerated bone repair. In conclusion, our results indicated that implanting 3D bioprinted scaffolds containing MSNs/BMP-4, BMSCs, and RAW264.7 cells in bone defects may be an effective method for improving diabetic bone repair, owing to the direct effects of BMP-4 on promoting osteogenesis of BMSCs and regulating M2 type macrophage polarization to improve the inflammatory microenvironment and secrete BMP-2.

Keywords: Bone morphogenic protein-4; Bone regeneration; Diabetic bone defect; Macrophage polarization; Three-dimensional bioprinting.