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The use of ultrasound of low intensity, parathyroid hormone or alendronate sodium in bone healing of femoral fractures in spinal cord injured rats

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Author(s):
Mariana Maloste Butezloff
Total Authors: 1
Document type: Doctoral Thesis
Press: Ribeirão Preto.
Institution: Universidade de São Paulo (USP). Faculdade de Medicina de Ribeirão Preto (PCARP/BC)
Defense date:
Examining board members:
Marcello Henrique Nogueira Barbosa; Sandra Yasuyo Fukada Alves; Rodrigo Gonçalves Pagnano; Antonio Carlos Shimano
Advisor: José Batista Volpon
Abstract

Background: Bone fracture is a frequent event in individuals with spinal cord injury (SCI) as a consequence of the marked reduction in bone mass and quality. SCI-induced bone loss may also induce changes in bone healing, leading to a poor callus formation and even non-unions. Therefore, the search for therapeutic interventions that may improve bone healing in this particular population may have a remarkable clinical importance. Purpose: To evaluate the influence of sodium alendronate, parathyroid hormone and low intensity ultrasound on the quality of fracture bone callus formation in SCI rats. Material and Methods: 75 male Wistar rats were randomly divided into five groups (n=15) (1) CON: control rats subjected to fracture, but not to spinal cord injury; (2) SCI: spinal cord injured rats and femur bone fracture; (3) SCI+ALE: spinal cord injured rats with bone fracture and treatment with sodium alendronate; (4) SCI+PTH: spinal cord injured rats with bone fracture and treatment with parathyroid hormone, and (5) SCI+LIPUS: spinal cord injured rats with bone fracture and treatment with low intensity ultrasound. A complete transection of the spinal cord was performed at the T10 level. In the control group the spinal cord was exposed but not sectioned. At 10 days post-injury (or Sham) a bone fracture was produced at the femoral shaft and fixed with an intramedullary pin. The ALE and PTH treatments began on day 1, and US began on day 3, after fracture and on day 14 all rats were euthanized. Non-fractured tibias and femur bone callus were analyzed by DXA, micro-computed tomography (?CT), histology, histomorphometry, immunohistochemistry (OPG, RANK and RANKL), mechanical test, real time PCR and ELISA (OPG and IGF-1). Results: SCI significantly impaired the bone quality, downregulated the osteoblastic-related gene expression and increased bone resorption, resulting in several phenotypic changes. SCI deteriorated the microarchitecture, reduced bone mass and weakened bone strength. Bone healing in SCI occurred predominantly by intramembranous ossification, leading to a poor callus formation. Conversely, the administration of alendronate, PTH and LIPUS were effective at ameliorating and even fully reestablish the bone microarchitecture, cells activity and mechanical strength. Similarly, both the pharmacological and mechanical therapeutics analyzed in this study were potentially efficient to increase bone callus density, to improve callus microstructure and metabolism, and to increase newly bone strength. In short,we revealed that SCI induced severe bone deterioration and changes in bone healing, which were ameliorated and even fully restored by the administration of alendronate, PTH, LIPUS and passive standing. Conclusions: The therapeutic approaches used in this study had great efficacy in restoring non-fractured bone integrity and with improvement of bone callus in paraplegic rats. (AU)

FAPESP's process: 16/13026-6 - The use of low-intensity ultrasound, parathyroid hormone or sodium alendronate on the bone healing of femurs in rats with spinal cord injury
Grantee:Mariana Maloste Butezloff
Support type: Scholarships in Brazil - Doctorate