title: Strontium exerts dual effects on calcium phosphate cement: Accelerating the degradation and enhancing the osteoconductivity both in vitro and in vivo.
abstract: Calcium phosphate cements (CPCs) have long been used as osteoconductive bone substitutes in the treatment of bone defects. However, the degradation rate of CPC is typically too slow to match the new bone growth rate. It is known that strontium increases the solubility of hydroxyapatite as well as exerts both anabolic and anticatabolic effects on bone. Therefore, we hypothesized that the incorporation of strontium would accelerate the degradation rate and enhance the osteoconductivity of CPC. In this study, Three groups, CPC (0% Sr-CPC), 5% Sr-CPC, and 10% Sr-CPC, were prepared, with the total molar ratio for Sr/(Sr+Ca) in the cement powder phase being 0, 5, and 10%, respectively. In the immersion test, less residual weight was observed in both 5% Sr-CPC and 10% Sr-CPC groups than CPC group. In addition, a higher osteoblastic cell proliferation rate and alkaline phosphatase activity were obtained in the strontium groups. In a rat femur bone defect model comparing CPC with 10% Sr-CPC, at 2 weeks postoperation, early endochondral ossification was found in the 10% Sr-CPC group, whereas only fibrous tissue was observed in control group; at 4-16 weeks postoperation, progressive osteoconduction toward the cement was observed in both groups. At 32 weeks, a higher peri-cement bone area and reduced cement area were noted in the 10% Sr-CPC group. In conclusion, in the 10% Sr-CPC group, strontium exerts dual effects on CPC: accelerating degradation rate and enhancing osteoconductivity, as shown here both in vitro and in vivo.
authors.affiliation: Shenzhen Key Laboratory for Innovative Technology in Orthopaedic Trauma, Department of Orthopaedics and Traumatology, The University of Hong Kong-Shenzhen Hospital, The University of Hong Kong, Shenzhen, China.
authors.forename: Guan-Ming
authors.initials: GM
authors.lastname: Kuang
authors.forename: W P
authors.initials: WP
authors.lastname: Yau
authors.forename: Jun
authors.initials: J
authors.lastname: Wu
authors.forename: Kelvin W K
authors.initials: KW
authors.lastname: Yeung
authors.forename: Haobo
authors.initials: H
authors.lastname: Pan
authors.forename: W M
authors.initials: WM
authors.lastname: Lam
authors.forename: W W
authors.initials: WW
authors.lastname: Lu
authors.forename: K Y
authors.initials: KY
authors.lastname: Chiu
mesh_terms: D000818:Animals; D001843:Bone Cements / Q000494:pharmacology*; D001861:Bone Regeneration / Q000187:drug effects*; D001842:Bone and Bones / Q000187:drug effects / Q000473:pathology / Q000648:ultrastructure; D002130:Calcium Phosphates / Q000494:pharmacology*; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D051379:Mice; D008970:Molecular Weight; D016062:Porosity; D011208:Powders; D017207:Rats, Sprague-Dawley; D013324:Strontium / Q000494:pharmacology*; D014961:X-Ray Diffraction
chemical_list: D001843:Bone Cements; D002130:Calcium Phosphates; D011208:Powders; C020243:calcium phosphate; D013324:Strontium
keywords: calcium phosphate cement; degradation; osteoconductivity; strontium