Development of a Metaphyseal Non-Union Model in the Osteoporotic Rat Femur

Abstract

The aim of this current study was to establish a metaphyseal femoral non-union model in osteoporotic rats by comparing a power tool versus a manual tool for fracture creation. Twelve adult female Sprague Dawley rats were ovariectomized (OVX) and received a special diet for 6 weeks. Biweekly pQCT measurements confirmed a significant reduction in the cancellous and total bone mineral density in OVX rats compared to control (CTRL) animals. After 6 weeks, OVX rats underwent surgery creating a distal metaphyseal osteotomy, either using a piezoelectric- (n = 6) or a manual Gigli wire (n = 6) saw. Fractures were stabilized with a Y-shaped mini-locking plate. Within each group, three rats received Alginate directly into the fracture gap. OVX animals gained more weight over 8 weeks compared to CTRL animals. pQCT analysis showed a significant difference in the volumetric cancellous bone mineral density between OVX and CTRL rats. A histological examination of the osteoporotic phenotype was completed. Radiographic evaluation and Masson–Goldner trichrome staining with the piezoelectric saw failed to demonstrate bony bridging or a callus formation. New bone formation and complete healing were seen after 6 weeks in the Gigli group. For the creation of a metaphyseal atrophic non-union in the osteoporotic bone, a piezoelectric saw should be used.

Synergistic effect of umbilical cord extracellular vesicles and rhBMP-2 to enhance the regeneration of a metaphyseal femoral defect in osteoporotic rats

“…The objective of the current study was to explore the possible synergistic effects of human umbilical cordderived mesenchymal stem cell-secreted extracellular vesicles in enhancing rhBMP-2-mediated bone repair in osteoporotic bone, utilizing a previously established metaphyseal rat femur defect model [17]. Based on the analysis of native X-rays, semi-quantitative and descriptive histology, micro-computed tomography (µCT), and biomechanical evaluations, we demonstrate that a single, orthotopic administration of hUC-MSC-sEVs in combination with a low dose of rhBMP-2 resulted in the most favorable outcomes for fracture healing.…”

“…After an appropriate acclimatization phase, all rats underwent a ventral ovariectomy (OVX, n = 64) and osteoporosis was further induced by feeding a calcium-, phosphorus-, vitamin D3-, soy-and phytoestrogen-free diet (Altromin-C1034, Altromin Spezialfutter GmbH, Lage, Germany) for a total of six weeks as previously described in Deluca et al [17]. Subsequently, all animals underwent right femoral surgery to create an osteotomy gap with a Gigli wire saw as published [17]. Briefly, thirty minutes preoperatively all rats received 0,03 mg/ kg buprenorphine as a subcutaneous (s. c.) injection and inhalation anesthesia (isoflurane) was induced.…”

“…All native radiographs, µCT images, and histological sections were evaluated by three independent observers (Author 1, 4, and 10) who were blinded to the groups. The radiographs and µCTs were scored for callus formation, quality of union, and bone remodeling after 6 weeks as previously described [17,21] and summarized in Table 1. The maximum expected total score is 8 for bone fracture repair.…”

“…The maximum expected total score is 8 for bone fracture repair. The histological sections were evaluated by the same investigators for fracture healing and scored as summarized in Table 2 [17,21] at 4 and 6 weeks after treatment. The maximum total histological score for bone fracture healing achievable is 12.…”

“…The combination of osteoinductive scaffolds with umbilical cord-derived mesenchymal stem cell-secreted extracellular vesicles (UC-MSC-sEVs) has previously shown promising results in enhancing in vivo bone repair [17,18]. While this approach has demonstrated efficacy, there is an intriguing potential for the combination of human hUC-MSC-sEVs with a low dose of recombinant human (rh)BMP-2 to further enhance bone healing.…”