Amlodipine accelerates bone healing in a stable closed femoral fracture model in mice

Abstract

Calcium channel blockers (CCBs), which are widely used in the treatment of hypertension, have been shown to influence bone metabolism. However, there is little information on whether CCBs also influence the process of fracture healing. Therefore, the effect of the CCB amlodipine on bone healing was studied in a stable closed fracture model in mice using intramedullary screw fixation. Bone healing was investigated by radiology, biomechanics, histomorphometry and Western blot analysis 2 and 5 weeks after fracture healing. Animals were treated daily (post operatively) per per os using a gavage with amlodipine low dose (1 mg/ kg body weight, n = 20), amlodipine high dose (3 mg/kg body weight, n = 20) or vehicle (NaCl) (control, n = 20) serving as a negative control. At 2 and 5 weeks, histomorphometric analysis revealed a significantly larger amount of bone tissue within the callus of amlodipine low-dose- and high-dose-treated animals when compared to controls. This was associated with a smaller amount of cartilaginous and fibrous tissue, indicating an acceleration of fracture healing. Biomechanics showed a slightly, but not significantly, higher bending stiffness in amlodipine low-dose- and high-dose-treated animals. Western blot analysis revealed a significantly increased expression of bone morphogenetic protein (BMP)-2 and vascular endothelial growth factor (VEGF). Moreover, the analysis showed a 5-fold higher expression of osteoprotegerin (OPG) and a 10-fold elevated expression of the receptor activator of NF-κB ligand (RANKL), indicating an increased bone turnover. These findings demonstrated that amlodipine accelerated fracture healing by stimulating bone formation, callus remodelling and osteoclast activity.

Development of an ischemic fracture healing model in mice

“…The 2-week time point was chosen to analyze the early time point of fracture healing, whereas the 5-week time point was used to investigate the long-term healing outcome of femoral fractures. Of note, we observed a reliable femoral fracture consolidation at 5 weeks after surgery with the present model in previous studies (8,9).…”

Sildenafil, a phosphodiesterase-5 inhibitor, stimulates angiogenesis and bone regeneration in an atrophic non-union model in mice

“…The late onset of this enhanced VEGF expression may be explained by the fact that the process of endochondral and intramembranous bone healing with subsequent formation of novel bone tissue is delayed in the segmental defect model used in the present study. Successful bone regeneration requires osteoclastmediated cartilage and bone resorption within the callus tissue [50]. Accordingly, we found a higher number of TRAP-positive osteoclasts within the callus tissue of sildenafil-treated animals.…”

Methods to accelerate fracture healing – a narrative review from a clinical perspective

“…Other drugs that have been considered to accelerate fracture healing include selective prostaglandin agonists ( 111 ), cyasterone ( 112 ), statins, and anti-sclerostin antibodies ( 113 ), but there is a lack of evidence from clinical studies in patients. In animal studies, amlodipine ( 114 ), cilostazol ( 115 ), L-arginin ( 116 ), sildenafil ( 117 ), and metformin ( 118 ) were shown to facilitate fracture healing. Aditionally, irisin ( 119 ), tumeric acid ( 120 ), aqueous extract of Prunus dulcis ( 121 ), and the Chinese acupuncture and herbal formula powder prescription ‘Zhèng Gŭ Zĭ Jīn Dān’ ( 122 ) are thought to accelerate fracture healing, but this has not yet been shown in clinical studies with patients and with an appropriate study design.…”