A Novel Hollow‐Tube‐Biphasic‐Whisker‐Modified Calcium Phosphate Ceramics with Simultaneously Enhanced Mechanical Strength and Osteogenic Activity

Abstract

Due to the inherent brittleness and low mechanical strength, it is still a challenge for calcium phosphate (Ca-P) ceramics to be used in load-bearing bone defect repair. To achieve a good balance between mechanical strength and osteogenic activity, hollow-tube-whisker-modified biphasic calcium phosphate (BCP) ceramics (BCP-HW) are successfully fabricated by an in situ growth process in the present study. Compared to the initial BCP ceramics (BCP-C) and those with solid whiskers, BCP-HW exhibits larger specific surface area (3.9 times vs BCP-C) and higher mechanical strength (3.4 times vs BCP-C), endowing it with stronger stimulation on adhesion, proliferation, and osteogenic differentiation of bone marrow mesenchymal stem cells. In an intramuscular implantation model of canine, BCP-HW shows excellent osteoinductivity and promotes the maturation of new bone, and the resultant compressive strength of the implant increases to ≈12 MPa at 3 months postoperatively. In another critical-sized segmental bone defect model of rabbit femur, BCP-HW has the best repairing effect. After implantation for 6 months, much more new bone ingrowth and higher bending load are observed in BCP-HW than BCP-C. Collectively, these findings suggest that the in situ hollow-tube whisker construction possesses immense potential in expanding the applications of Ca-P ceramics to load-bearing bone defect repair.

Construction of Vascularized Tissue Engineered Bone with nHA-Coated BCP Bioceramics Loaded with Peripheral Blood-Derived MSC and EPC to Repair Large Segmental Femoral Bone Defect

“…Previous studies have shown that micro-/nanotopography on Ca–P ceramic surfaces could modulate cell behavior. Compared with the microscale surface structure, the nanoscale surface structure of scaffolds can form more micropores and mesopores, thus promoting the deposition of proteins in these pores and providing abundant active sites for cell attachment. , …”

“…Compared with the microscale surface structure, the nanoscale surface structure of scaffolds can form more micropores and mesopores, thus promoting the deposition of proteins in these pores and providing abundant active sites for cell attachment. 9,43 Moreover, cells are particularly sensitive to the microstructure of the scaffold surface. The adhesion of cells on the microscale surface is realized by the mutual aggregation of multiple receptor molecules, and the structural rearrangement can occur with the change of the microscale topological structure of the surface of the scaffold.…”

“…8 However, in recent years, a growing number of studies proved that the bioceramics only need to meet the initial stability; their mechanical strength will be improved with the ingrowth of new bone tissue after implantation. 8,9 Meanwhile, most bioceramics will degrade slowly and finally achieve the regenerative repair of segmental bone defects. This is more in line with the idea of bone tissue engineering and regenerative medicine.…”

“…Biodegradable metals are the focus of current research, but their biodegradation behavior and biocompatibility still require further research. , Traditionally, the ceramic materials are not suitable for repairing segmental bone defects due to their inherent brittleness and poor mechanical properties . However, in recent years, a growing number of studies proved that the bioceramics only need to meet the initial stability; their mechanical strength will be improved with the ingrowth of new bone tissue after implantation. , Meanwhile, most bioceramics will degrade slowly and finally achieve the regenerative repair of segmental bone defects. This is more in line with the idea of bone tissue engineering and regenerative medicine.…”

Nanowhiskers Orchestrate Bone Formation and Bone Defect Repair by Modulating Immune Cell Behavior

“…Previous studies reported that biphasic calcium phosphate (BCP) ceramics with whisker surface structures present favorable bone regeneration and bone defect repair performance. , Herein, we fabricated BCP ceramics with nanowhisker surface structure to investigate their large-segment bone defect repair performance in a rabbit tibial model. Then, the immunomodulatory features of nanowhisker structures and which of them influence osteogenesis and biomaterial resorption were further investigated.…”