Alda Flores

University of Texas at San Antonio, San Antonio, Texas, United States

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Publications (3)13.86 Total impact

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    ABSTRACT: Statins have been shown to stimulate BMP2 transcription and bone formation. This raises the possibility that they could be useful for enhancing rates of fracture repair. Observational studies in patients treated with oral statins for lipid-lowering have been controversial. The likely reason for their inconsistent effects is that the statin concentration reaching the periphery was too low after oral administration to produce a reproducible biologic effect. Thus, we examined the effects of lovastatin (LV) given transdermally in a well-described preclinical model of fracture repair. Effects on the healing fracture callus were assessed by biomechanical strength, radiographs, and quantitative morphology. LV was administered transdermally (TD) for 5 days after fracture in several doses (0.1-5 mg/kg/d) and compared with vehicle-treated control rats and rats treated with LV by oral gavage (PO) at 5-25 mg/kg/d for 5 days from the day of fracture. Radiological evaluation of bones treated with TD LV showed enhanced fracture repair at 2 and 6 wk. BMD in the callus area at 6 wk was also increased in the TD group compared with vehicle-treated controls (p < 0.05). The force required to break TD-treated bones (0.1 mg/kg/d for 5 days) was 42% greater than vehicle-treated controls (p < 0.02), and there was a 90% increase in stiffness (p < 0.01). PO LV at much higher doses (10 and 25 mg/kg/d) showed increased stiffness but no change in other biomechanical properties. By histological examination, a significant increase was also observed in the size of the callus, surrounding proliferating cell nuclear antigen-positive cells, and osteoblast and osteoclast number in TD-treated rats compared with controls at day 8 after fracture (n = 6). In summary, we found that TD LV in low doses accelerates fracture healing, whereas 10-fold the lipid-lowering dose was required to produce any effect when it was administered orally. These studies provide valuable information on the potential of statins and TD delivery as a new and effective therapeutic modality in fracture repair.
    Journal of bone and mineral research: the official journal of the American Society for Bone and Mineral Research 08/2008; 23(11):1722-30. · 6.04 Impact Factor
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    ABSTRACT: Impaired bone formation contributes to the lack of bone healing in multiple myeloma and there is a need for agents with bone anabolic properties to reverse the bone deficit in patients. Bortezomib, a proteasome inhibitor with antitumour efficacy in myeloma patients, enhanced new bone formation in mouse calvarial cultures; this effect was blocked by dickkopf 1(Dkk1), an antagonist of Wnt signalling implicated in myeloma bone disease. Bortezomib inhibited Dkk1 expression in calvariae and bone marrow-derived stromal cells, suggesting a novel mechanism by which bortezomib exerts its effects in bone. Clinical trials in patients with myeloma bone disease are needed to validate these results.
    British Journal of Haematology 12/2007; 139(3):434-8. · 4.94 Impact Factor
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    ABSTRACT: Statins stimulate bone formation in vitro and in vivo and, when given in large doses or by prolonged infusions, stimulate biomechanical strength of murine long bones with healing fractures. However, administration of statins by large oral doses or prolonged infusions to a fracture site is not a feasible therapeutic approach to hasten healing of human fractures. We administered lovastatin in biodegradable polymer nanobeads of poly(lactic-co-glycolide acid) to determine if lovastatin delivered in low doses in nanoparticles of a therapeutically acceptable scaffold could increase rates of healing in a standard preclinical model of femoral fracture. We found that these nanobeads: (1) stimulated bone formation in vitro at 5 ng/mL, (2) increased rates of healing in femoral fractures when administered as a single injection into the fracture site, and (3) decreased cortical fracture gap at 4 weeks as assessed by microcomputed tomography. These preclinical results suggest that lovastatin administered in a nanobead preparation may be therapeutically useful in hastening repair of human fractures.
    Journal of Orthopaedic Research 11/2007; 25(10):1351-7. · 2.88 Impact Factor