Development of clinically relevant in vivo metastasis models using human bone discs and breast cancer patient-derived xenografts.

BACKGROUND: Late-stage breast cancer preferentially metastasises to bone; despite advances in targeted therapies, this condition remains incurable. The lack of clinically relevant models for studying breast cancer metastasis to a human bone microenvironment has stunted the development of effective treatments for this condition. To address this problem, we have developed humanised mouse models in which breast cancer patient-derived xenografts (PDXs) metastasise to human bone implants with low variability and high frequency. METHODS: To model the human bone environment, bone discs from femoral heads of patients undergoing hip replacement surgery were implanted subcutaneously into NOD/SCID mice. For metastasis studies, 7 patient-derived xenograft tumours (PDX: BB3RC32, ER+ PR+ HER2-; BB2RC08, ER+ PR+ ER2-; BB6RC37, ER- PR- HER2- and BB6RC39, ER+ PR+ HER2+), MDA-MB-231-luc2, T47D-luc2 or MCF7-Luc2 cells were injected into the 4th mammary ducts and metastases monitored by luciferase imaging and confirmed on histological sections. Bone integrity, viability and vascularisation were assessed by uCT, calcein uptake and histomorphometry. Expression profiling of genes/proteins during different stages of metastasis were assessed by whole genome Affymetrix array, real-time PCR and immunohistochemistry. Importance of IL-1 was confirmed following anakinra treatment. RESULTS: Implantation of femoral bone provided a metabolically active, human-specific site for tumour cells to metastasise to. After 4 weeks, bone implants were re-vascularised and demonstrated active bone remodelling (as evidenced by the presence of osteoclasts, osteoblasts and calcein uptake). Restricting bone implants to the use of subchondral bone and introduction of cancer cells via intraductal injection maximised metastasis to human bone implants. MDA-MB-231 cells specifically metastasised to human bone (70% metastases) whereas T47D, MCF7, BB3RC32, BB2RC08, and BB6RC37 cells metastasised to both human bone and mouse bones. Importantly, human bone was the preferred metastatic site especially from ER+ PDX (100% metastasis human bone compared with 20-75% to mouse bone), whereas ER-ve PDX developed metastases in 20% of human and 20% of mouse bone. Breast cancer cells underwent a series of molecular changes as they progressed from primary tumours to bone metastasis including altered expression of IL-1B, IL-1R1, S100A4, CTSK, SPP1 and RANK. Inhibiting IL-1B signalling significantly reduced bone metastasis. CONCLUSIONS: Our reliable and clinically relevant humanised mouse models provide significant advancements in modelling of breast cancer bone metastasis.

Losartan alters osteoblast differentiation and increases bone mass through inhibition of TGFB signalling in vitro and in an OIM mouse model.

Excessive production of Transforming Growth Factor ß (TGFß) is commonly associated with dominant and recessive forms of OI. Previous reports have indicated that administration of TGFß-targeted antibodies maybe of potential therapeutic benefit to OI patients. However, direct targeting of TGFß is likely to cause multiple adverse effects including simulation of autoimmunity. In the current study we use patient-derived normal and OI fibroblasts, osteoblasts and OIM mouse models to determine the effects of Losartan, an angiotensin II receptor type 1 (AT1) antagonist, on TGFß signalling and bone morphology in OI. In OIM mice bred on a mixed background administration of 0.6 g/L losartan for 4 weeks was associated with a significant reduction in TGFß from 79.2 g/L in the control to 60.0 ng/ml following losartan (p < 0.05), reduced osteoclast activity as measured by CTX from 275.9 ng/ml in the control to 157.2 ng/ml following 0.6 g/L of losartan (p < 0.05) and increased cortical bone thickness (P < 0.001). Furthermore in OIM mice bred on a C57BL/6 background 0.6 g/L losartan increased trabecular bone volume in the tibiae (P < 0.05) and the vertebrae (P < 0.01), increased cortical bone thickness (P < 0.001) reduced the trabecular pattern factor (P < 0.01 and P < 0.001 for the tibiae and vertebrae respectively), reduced osteoclast (P < 0.05) and osteoblast (P < 0.01) numbers as well as reducing the area of bone covered by these cell types. Interestingly, losartan did not affect immune cells infiltrating into bone, nor did this drug alter TGFß signalling in normal or OI fibroblasts. Instead, losartan reduced SMAD2 phosphorylation in osteoblasts, inhibiting their ability to differentiate. Our data suggest that losartan may be an effective treatment for the bone-associated dysmorphia displayed in OI whilst minimising potential adverse immune cell-related effects.

Osteogenesis imperfecta in children.

Osteogenesis imperfecta (OI) is a disease characterised by altered bone tissue material properties together with abnormal micro and macro-architecture and thus bone fragility, increased bone turnover and hyperosteocytosis. Increasingly appreciated are the soft tissue changes, sarcopenia in particular. Approaches to treatment are now multidisciplinary, with bisphosphonates having been the primary pharmacological intervention over the last 20 years. Whilst meta-analyses suggest that anti-fracture efficacy across the life course is equivocal, there is good evidence that for children bisphosphonates reduce fracture risk, increase vertebral size and improve vertebral shape, as well as improving motor function and mobility. The genetics of OI continues to provide insights into the molecular pathogenesis of the disease, although the pathophysiology is less clear. The complexity of the multi-scale interactions of bone tissue with cellular function are gradually being disentangled, but the fundamental question of why increased tissue brittleness should be associated with so many other changes is unclear; ER stress, pro-inflammatory cytokines, accelerated senesence and altered matrix component release might all contribute, but a unifying hypothesis remains elusive. New approaches to therapy are focussed on increasing bone mass, following the paradigm established by the treatment of postmenopausal osteoporosis. For adults, this brings the prospect of restoring previously lost bone - for children, particularly at the severe end of the spectrum, the possibility of further reducing fracture frequency and possibly altering growth and long term function are attractive. The alternatives that might affect tissue brittleness are autophagy enhancement (through the removal of abnormal type I collagen aggregates) and stem cell transplantation - both still at the preclinical stage of assessment. Preclinical assessment is not supportive of targeting inflammatory pathways, although understanding why TGFb signalling is increased, and whether that presents a treatment target in OI, remains to be established.

Baseline Characteristics of the Paediatric Observation Priority Score in Emergency Departments outside Its Centre of Derivation.

OBJECTIVES AND BACKGROUND: Scoring systems in Emergency Departments (EDs) are rarely validated. This study aimed to examine the Paediatric Observation Priority Score (POPS), a method of quantifying patient acuity, in EDs in the United Kingdom, and determine baseline performance characteristics. METHODS: POPS was implemented in 4 EDs for children (ages of 0 to 16) with participants grouped into 3 categories: discharged from ED, discharged but with return within 7 days, and admitted for less or more than 24 hours. RESULTS: 3323 participants with POPS scores ranging from 0 to 11 (mean = 2.33) were included. The proportion of each POPS score varied between sites with approximately 10-20% being POPS 0 and 12-25% POPS greater than 4. Odds ratio of readmission with POPS 5-9 against 0-4 was 2.05 (CI 1.20 to 3.52). POPS 0-4 showed no significant difference (p = 0.93) in relation to admission/discharge rates between sites with a significant difference found (p < 0.01) for POPS > 5. CONCLUSION: It is feasible to implement POPS into EDs with similar performance characteristics to the original site of development. There is now evidence to support a wider health service evaluation to refine and improve the performance of POPS.