Delayed short‐course treatment with teriparatide (PTH1–34) improves femoral allograft healing by enhancing intramembranous bone formation at the graft–host junction

Clinical management of critical bone defects remains a major challenge. Despite preclinical work demonstrating teriparatide (PTH_1–34) effectiveness in small animals, inconclusive data from clinical trials have raised questions of dose and regimen. To address this, we completed a comprehensive study in the murine femoral allograft model, to assess the effects of dose (0.4, 4, and 40 µg/kg/day) and various treatment regimens on radiographic, histologic, and biomechanical healing at 2, 4, and 9 weeks. Only the high dose (40 µg/kg) of PTH_1–34 demonstrated significant effects when given daily over 9 weeks. Remarkably, equivalent biomechanical results were obtained with delayed, short treatment from 2 to 6 weeks that did not induce a significant increase in endochondral bone formation and callus volume. In contrast, PTH_1–34 treatment from 1 to 5 weeks postop demonstrated similar osteogenic effects as immediate daily treatment for 9 weeks, but failed to achieve a significant increase in biomechanics at 9 weeks. MicroCT and histologic analyses demonstrated that the 2‐week delay in treatment allowed for timely completion of the endochondral phase, such that the prominent effects of PTH_1–34 were enhanced intramembranous bone formation and remodeling at the graft–host junction. These findings support the potential use of PTH_1–34 as an adjuvant therapy for massive allograft healing, and suggest that there may be an ideal treatment window in which a short course is administered after the endochondral phase to promote osteoblastic bone formation and remodeling to achieve superior union with modest callus formation. © 2012 American Society for Bone and Mineral Research     

BMP‐7–induced ectopic bone formation and fracture healing is impaired by systemic NSAID application in C57BL/6‐mice

Nonsteroidal antiinflammatory drugs (NSAIDs) are known to potentially impair the fracture healing process. The aim of the present study was to determine if the impairment of bone healing by systemic NSAID application is, at least in part, due to an interaction of NSAIDs with the bone anabolic BMP‐7 pathway. Therefore, we first analyzed fracture healing in control and diclofenac‐treated mice, where we not only found a significant impairment of fracture healing due to diclofenac treatment as assessed by biomechanical testing and µCT imaging, but also found high coexpression of bone morphogenetic protein‐7 (BMP‐7) and cyclooxygenase‐2 (COX‐2) within the fracture callus of both groups. To experimentally address the possible interaction between BMP‐7 and COX‐2, we then induced ectopic bone formation in control (n = 10) and diclofenac‐treated mice (n = 10) by application of BMP‐7 (recombinant human OP‐1, rhOP‐1) into the hamstring muscles. After 20 days of treatment, each ectopic bone nodule was analyzed by contact‐radiography, µCT, histology, and histomorphometry. Diclofenac application decreased the trabecular number and bone mass in the ectopic bone nodules significantly due to reduced osteoblast number and activity. These data demonstrate that the bone anabolic effect of BMP‐7 and fracture healing is impaired by diclofenac application, and suggest that the potential negative impact of NSAIDs on fracture healing is, at least in part, due to interference with BMP‐7 signaling. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:785–791, 2010     

Patient HSP70‐hom TG haplotype is associated with decreased transplant‐related mortality and improved survival after sibling HLA‐matched hematopoietic stem cell transplantation

Kim I, Kim JH, Rhee JY, Kim JW, Cho HJ, Cho E‐Y, Lee J‐E, Hong Y‐C, Park SS, Yoon S‐S, Park MH, Park S, Kim BK. Patient HSP70‐hom TG haplotype is associated with decreased transplant‐related mortality and improved survival after sibling HLA‐matched hematopoietic stem cell transplantation.
Clin Transplant 2010: 24: 459–466.
© 2009 John Wiley & Sons A/S. Abstract: Heat shock protein 70‐hom (HSP70‐hom) plays an important role in protein folding and immune responses. Therefore, HSP70‐hom gene polymorphisms may act as important factors in predicting the prognosis of patients receiving allogeneic hematopoietic stem cell transplantation (HSCT). To evaluate the role of HSP70‐hom gene polymorphisms in the prognosis of patients receiving sibling human leukocyte antigen (HLA)‐matched allogeneic HSCT, the HSP70‐hom polymorphisms, T2437C and G2763A, were genotyped in 147 patients receiving sibling HLA‐matched allogeneic HSCT. Individual diplotypes were estimated from genotype data of the two HSP70‐hom polymorphisms using the expectation maximization algorithm. Patients with the 2763GG or GA genotype showed longer overall survival compared with those with the 2763AA genotype, and patients with a TG haplotype (TG/TA, TG/TG or TG/CG) also showed longer overall survival compared with those with a non‐TG haplotype (TA/TA or TA/CG) (both G2763A genotype and diplotype, p < 0.01). Moreover, the 2437TT genotype was found to be protective for treatment‐related death compared with the 2437TC genotype, and a TG haplotype was found to be very protective for treatment‐related death compared with a non‐TG haplotype (T2437C genotype, p = 0.04; and diplotype, p = 0.02). Therefore, our results suggest that HSP70‐hom polymorphisms play an important role in the prognosis of patients receiving sibling HLA‐matched allogeneic HSCT.     

Unique angiogenic and vasculogenic properties of renal cell carcinoma in a xenograft model of bone metastasis are associated with high levels of vegf‐a and decreased ang‐1 expression

Management of various tumor metastases to bone has dramatically improved, but this is not so for renal cell carcinoma (RCC), which is a difficult surgical problem due to its great vascularity. Furthermore, the unique mechanisms that mediate RCC vasculogenesis in bone remain unknown. To understand this process we developed a xenograft model that recapitulates highly vascular RCC versus less vascular tumors that metastasize to bone. Human tumor cell lines of RCC (786‐O), prostate cancer (PC3), lung cancer (A549), breast cancer (MDA‐MB231), and melanoma (A375) were transduced with firefly luciferase (Luc), injected into the tibiae of nude mice, and differences in growth, osteolysis, and vascularity were assessed by longitudinal bioluminescent imaging, micro‐CT for measurement of calcified tissues and vascularity and histology. The results showed that while RCC‐Luc has reduced growth and osteolytic potential versus the other tumor lines, it displayed a significant increase in vascular volume (p < 0.05). This expansion was due to 3‐ and 5‐fold increases in small and large vessel numbers respectively. In vitro gene expression profiling revealed that RCC‐Luc expresses significantly (p < 0.05) more vegf‐a (10‐fold) and 20‐ to 30‐fold less ang‐1 versus the other lines. These data demonstrate the utility of this model to study the unique vasculogenic properties of RCC bone metastases. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 30:325–333, 2012     

Distribution of TRAP‐positive cells and expression of HIF‐1α, VEGF,and FGF‐2 in the reparative reaction in patients with osteonecrosis of the femoral head

Osteogenesis and angiogenesis are closely associated with the reparative process in bone. In osteonecrosis of the femoral head (ONFH), although the progression of bone resorption by osteoclasts is considered to be followed by femoral head collapse, the reparative reaction remains unknown. In order to investigate the reparative reaction in patients with ONFH, the distribution of TRAP‐ positive cells and expression of HIF‐1α, VEGF, and FGF‐2 were observed in 51 hips in 42 patients. TRAP‐positive cells were detected around the teres insertion and retinaculum in the early radiologic stage, and increased around the new trabecular bone throughout the reparative interface zone in the late collapsed stage. HIF‐1α expression was detected at the fibrosis area and the transitional area, which included the proximal area of the reparative interface zone adjacent to the necrotic zone. VEGF was expressed at the edematous area of the reparative interface zone, while FGF‐2 was detected widely in the reparative interface zone and the normal zone. In the late radiologic stages, HIF‐1α, VEGF, and FGF‐2 were not detected in the necrotic zone, and they acted in angiogenesis in the reparative interface zone, while TRAP‐positive cells increased around the new bone formation in response to remodeling after the collapse. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27: 694–700, 2009