Mesenchymal stem cells (MSCs) have great therapeutic potential, with the capacity to influence diverse medical applications, such as tissue engineering and gene therapy. Our findings indicate that autocrine Wnt signaling operates in primitive MSC populations and supports previous evidence that Wnt signaling regulates mesenchymal lineage specification. The identification of a putative common Wnt/Fz molecular signature in MSCs will contribute to our understanding of the molecular mechanisms that regulate self-renewal and lineage-specific differentiation.

Biodegradable polymer/hydroxyapatite (HA) composites have potential application as bone graft substitutes. Thin films of polymer/HA composites were produced, and the initial attachment of primary human osteoblasts (HOBs) was assessed to investigate the biocompatibility of the materials. Poly(epsilon-caprolactone) (PCL) and poly(L-lactic acid) (PLA) were used as matrix materials for two types of HA particles, 50-microm sintered and submicron nonsintered. Using ESEM, cell morphology on the surfaces of samples was investigated after 90 min, 4 h, and 24 h of cell culture. Cell activity and viability were assessed after 24 h of cell culture using Alamar blue and DNA assays. Surface morphology of the polymer/HA composites and HA exposure were investigated using ESEM and EDXA, respectively. ESEM enabled investigation of both cell and material surface morphology in the hydrated condition. Combined with EDXA it permitted chemical and visual examination of the composite. Differences in HA exposure were observed on the different composite surfaces that affected the morphology of attached cells. In the first 4 h of cell culture, the cells were spread to a higher degree on exposed HA regions of the composites and on PLA than they were on PCL. After 24 h the cells were spread equally on all the samples. The cell activity after 24 h was significantly higher on the polymer/HA composites than on the polymer films. There was no significant difference in the activity of the cells on the various composite materials. However, cells on PCL showed higher activity compared to those on PLA. A polymer surface exhibiting "point exposure" of HA appeared to provide a novel and favorable substrate for primary cell attachment. The cell morphology and activity results indicate a favorable cell/material interaction and suggest that PLA and PCL and their composites with HA may be candidate materials for the reconstruction of bony tissue. Further investigations regarding long-term biomaterial/cell interactions and the effects of acidic degradation products from the biodegradable polymers are required to confirm their utility.

Multiple myeloma (MM) is associated with the development of osteolytic bone disease, mediated by increased osteoclastic bone resorption and impaired osteoblastic bone formation. Dickkopf-1 (Dkk1), a soluble inhibitor of wingless/int (Wnt) signaling and osteoblastogenesis, is elevated in patients with MM and correlates with osteolytic bone disease. In this study, we investigated the effect of inhibiting Dkk1 on the development of osteolytic lesions in the 5T2MM murine model of myeloma. We showed that Dkk1 is expressed by murine 5T2MM myeloma cells. Injection of 5T2MM cells into C57BL/KaLwRij mice resulted in the development of osteolytic bone lesions (p < 0.05), mediated by increased osteoclast numbers (p < 0.001) and a decrease in osteoblast numbers (p < 0.001) and mineralizing surface (p < 0.05). Mice bearing 5T2MM cells were treated with an anti-Dkk1 antibody (BHQ880, 10 mg/kg, IV, twice weekly for 4 wk) from time of paraprotein detection. Anti-Dkk1 treatment prevented 5T2MM-induced suppression of osteoblast numbers (p < 0.001) and surface (p < 0.001). Treatment increased mineralizing surface by 28% and bone formation rate by 25%; however, there was no change in mineral apposition rate. Inhibiting Dkk1 had no effect on osteoclast numbers. mCT analysis showed that anti-Dkk1 treatment significantly protected against 5T2MM-induced trabecular bone loss (p < 0.05) and reduced the development of osteolytic bone lesions (p < 0.05). Treatment had no significant effect on tumor burden. These data suggest that inhibiting Dkk1 prevents the suppression of bone formation and in doing so is effective in preventing the development of osteolytic bone disease in myeloma, offering an effective therapeutic approach to treating this clinically important aspect of myeloma.

Progressive histologic changes occur in the pulmonary arteries and arterioles, as a complication of chronically elevated pulmonary arterial blood pressure, in patients with congenital septal defects of the heart. This progression is so stereotyped as to allow a division of the structural effects into 6 grades. The histologic features of each grade are described in detail in this communication. These results afford a basis for comparing the magnitude of these changes to the clinical findings.

Bortezomib reduces serum dickkopf-1 and receptor activator of nuclear factor-jB ligand concentrations and normalises indices of bone remodelling in patients with relapsed multiple myeloma Bortezomib is a proteasome inhibitor that is currently indicated for patients with multiple myeloma (MM) who have received at least one prior therapy. Although the anti-myeloma effect of bortezomib has been clearly demonstrated, its effect on bone metabolism is still unclear. In addition to increased bone resorption, bone formation is suppressed in patients with myeloma (Silvestris et al, 2004). There are recent reports that bortezomib may increase serum alkaline phosphatase activity, which is consistent with enhanced osteoblast function (Shimazaki et al, 2005;Zangari et al, 2005). However, knowledge of the molecular mechanisms that are involved and the effect bortezomib also has on bone resorption is still lacking. Dickkopf-1 (DKK-1) protein is an inhibitor of Wnt signalling that participates in osteoblast dysfunction in MM (Tian et al, 2003). The receptor activator of nuclear factor-kappa B ligand (RANKL), RANK and osteoprotegerin (OPG) system is considered the final mediator of osteoclastogenesis as well as osteoclast activation in myeloma [Terpos et al, 2003a]. Therefore, this study aimed to evaluate the effect bortezomib has on RANKL and DKK-1 serum levels in MM patients and determine if this correlates to markers of bone metabolism. Patients and methods PatientsThirty-four myeloma patients who had relapsed after previous therapies were evaluated ( SummaryThe effect of bortezomib on bone remodelling was evaluated in 34 relapsed myeloma patients. At baseline, patients had increased serum concentrations of dickkopf-1 (DKK-1), soluble receptor activator of nuclear factor-jB ligand (sRANKL), sRANKL/osteoprotegerin ratio, C-telopeptide of type-I collagen (CTX) and tartrate-resistant acid phosphatase isoform-5b (TRACP-5b); bone-alkaline phosphatase and osteocalcin were reduced. Serum DKK-1 correlated with CTX and severe bone disease. Bortezomib administration significantly reduced serum DKK-1, sRANKL, CTX, and TRACP-5b after four cycles, and dramatically increased bone-alkaline phosphatase and osteocalcin, irrespective of treatment response. This is the first study showing that bortezomib reduces DKK-1 and RANKL serum levels, leading to the normalisation of bone remodelling in relapsed myeloma.

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The oral administration of Crotalaria spectabilis seeds to young rats induces pulmonary hypertension in them associated with right ventricular hypertrophy and an increase in the medial thickness of the pulmonary trunk and muscular pulmonary arteries. This appears to be the first direct demonstration that the oral administration of an agent may bring about pulmonary hypertension.Young rats fed on a diet which contains Crotalaria spectabilis seeds or the pyrrolizidine alkaloid monocrotaline die from congestive heart failure within 36 to 60 days. At necropsy they are found to have ascites, pleural effusions, and cardiac enlargement due to right ventricular hypertrophy (Turner and Lalich, 1965;Kay and Heath, 1966). Microscopic examination reveals an increase in the medial thickness of the pulmonary trunk (Heath and Kay, 1967) and small pulmonary arteries (Turner and Lalich, 1965 ;Kay and Heath, 1966), and in about one-third of the animals an acute necrotizing pulmonary arteritis (Lalich and Merkow, 1961;Kay and Heath, 1966). Since similar changes in the heart weight and pulmonary vasculature in man are well known to be associated with severe pulmonary hypertension (Wagenvoort, Heath, and Edwards, 1964) we thought it likely that the pulmonary vascular lesions produced in rats by Crotalaria spectabilis seeds are also associated with an elevation of the pulmonary artery pressure. It has never been shown that the oral administration of any agent can produce pulmonary hypertension, so we considered that its direct demonstration in rats fed with such seeds would be of considerable significance. Accordingly we measured right atrial and ventricular pressures in a group of rats maintained on a diet containing Cratalaria spectabilis seeds and compared these with values obtained from a group of control rats. In addition, we investigated the relation between right ventricular systolic pressure on the one hand, and the medial thickness of the small pulmonary arteries and the pulmonary trunk and the right ven-tricular weight on the other. METHODSThirteen female weanling Wistar alibino rats (initial weight 65 to 79 g.) were individually marked and divided into two groups comprising five test animals and eight controls. They were weighed at the outset of the experiment and three times weekly until its conclusion. The test animals received a diet of powdered Thomson rat cubes to which had been added finely ground Crotalaria spectabilis seeds to give a concentration of 0-1%. Control animals were given unadulterated powdered rat cubes. All animals had free access to food and water.The intracardiac pressures were determined by introducing a fine metal cannula connected to a capacitance manometer into the right jugular vein under light ether anaesthesia and advancing it along the superior vena cava into the right atrium and then into the right ventricle. It proved impossible to measure the pulmonary artery pressure directly, but for the purposes of this experiment the right ventricular systolic pressure was regarded as being equivalent ...

Dickkopf-1 (DKK-1) protein, a soluble inhibitor of Wnt signalling, has been implicated in the pathogenesis of myeloma bone disease through the suppression of osteoblast differentiation. In this study, serum concentrations of DKK-1 were measured in 50 myeloma patients (32 at diagnosis and 18 before and after autologous stem cell transplantation (ASCT), 18 patients with monoclonal gammopathy of undetermined significance (MGUS), and 22 healthy controls. Serum DKK-1 levels were increased in MM at diagnosis compared with MGUS (mean 6 SD: 67 6 54 ng/mL vs. 38 6 13 ng/mL; p 5 0.006) and controls (31 6 11 ng/mL; p 5 0.02), while there was no difference between MGUS patients and controls. Although patients with stage 2 and 3 myeloma had higher DKK-1 values than stage 1 patients (79 6 63 vs. 40 6 13; p 5 0.005), no significant correlation between serum DKK-1 and myeloma bone disease was observed. Myeloma patients before ASCT also had increased levels of DKK-1 (63 6 77 ng/mL; p 5 0.03) compared with controls, supporting the notion that DKK-1 may be responsible for the suppressed osteoblast activity even in patients with low tumor burden. After ASCT, there was a sustained decrease in DKK-1 levels over time, while bone formation markers elevated, suggesting that the reduction of DKK-1 levels after ASCT may correlate with the normalization of osteoblast function. These results could provide the basis for developing agents that block DKK-1, thus restoring osteoblast function and counteracting the increased osteoclastogenesis observed in myeloma. ' 2006 Wiley-Liss, Inc.