In an unselected population of ESRF patients already, 62% of them have an abnormal bone histology. ABD is the most prevalent type of ROD in this population. In the absence of aluminium or strontium accumulation the relatively high prevalence of a low bone turnover as expressed by either normal bone or ABD and OM is striking.

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Abstract. Adequate control of phosphate levels remains an important issue in patients with chronic renal failure (CRF). Lanthanum carbonate has been proposed as a new phosphate binder. Previous studies have shown a high phosphate binding capacity (Ͼ97%) and low gastrointestinal absorption of lanthanum, without serious toxic side effects in the presence of a normal renal function (NRF). Because of lanthanum's physicochemical resemblance to calcium, the possible effects of it on bone have to be considered. The aim of this study was to investigate the effects of lanthanum carbonate on bone histology in NRF and CRF rats after oral administration of the compound with doses of 100, 500, or 1000 mg/kg per d for 12 wk. Bone histomorphometry showed that CRF animals that received vehicle developed secondary hyperparathyroidism. Urinalysis of lanthanum-loaded CRF animals showed a dosedependent decrease in urinary phosphorus excretion, which was clearly more pronounced in the CRF groups compared with NRF animals. Phosphatemia, however, remained normal. Lanthanum carbonate administration induced a dose-dependent decrease in bone formation rate and increase in osteoid area in CRF animals. Three of seven animals in the CRF-1000 group and one of eight animals in the NRF-100 group were classified as having a mineralization defect. The number of cuboidal osteoblasts, however, was not affected, indicating that bone changes were not due to a toxic effect of lanthanum on the osteoblast. Furthermore, lanthanum concentrations in the femur remained low and did not correlate with histomorphometric parameters. These findings suggest that the administration of high doses of phosphate binder (1000 mg/kg per d lanthanum carbonate), in combination with decreased 25-(OH) vitamin D 3 in the uremic state, resulted in phosphate depletion and followed by an increased mobilization of phosphorus out of bone and/or reduced incorporation into bone. There was no evidence that lanthanum had a direct toxic effect on osteoblasts.

Background. Hyperphosphataemia is a risk factor for arterial calcification contributing to the high cardiovascular mortality in patients with chronic kidney disease. Calciumbased phosphate binders can induce hypercalcaemia and are associated with progression of vascular calcification. Therefore, the effect of lanthanum carbonate, a non-calcium phosphate binder, on the development of vascular calcification was investigated in uraemic rats. Methods. Chronic renal failure (CRF) was induced by feeding rats an adenine-enriched diet for 4 weeks. After 2 weeks, 1% or 2% lanthanum carbonate was added to the diet for 6 weeks. Calcification in the aorta, carotid and femoral arteries was evaluated histomorphometrically, biochemically and by ex vivo micro-CT. Chondro-/osteogenic conversion of vascular smooth muscle cells was also analysed in the rat aorta. Results. Treatment with 1% lanthanum carbonate (1% La) did not reduce vascular calcification, but in the 2% lanthanum carbonate (2% La) group vascular calcium content and area% Von Kossa positivity were decreased compared with control CRF rats. The aortic calcified volume measured with ex vivo micro-CT was significantly reduced in rats treated with 2% La. Although calcification was inhibited by treatment with 2% La, the chondrocyte transcription factor sox-9 was abundantly expressed in the aorta. Conclusion. Treatment of CRF rats with 2% La reduces the development of vascular calcification by adequate phosphate binding resulting in a decreased supply of phosphate as a substrate for vascular calcification.

The most common cause of death in the intensive care unit (ICU) is the development of multiorgan dysfunction syndrome (MODS). Besides life-supporting treatments, no cure exists, and its mechanisms are still poorly understood. Catalytic iron is associated with ICU mortality and is known to cause free radical-mediated cellular toxicity. It is thought to induce excessive lipid peroxidation, the main characteristic of an iron-dependent type of cell death conceptualized as ferroptosis. Here we show that the severity of multiorgan dysfunction and the probability of death are indeed associated with plasma catalytic iron and lipid peroxidation. Transgenic approaches underscore the role of ferroptosis in iron-induced multiorgan dysfunction. Blocking lipid peroxidation with our highly soluble ferrostatin-analogue protects mice from injury and death in experimental non-septic multiorgan dysfunction, but not in sepsis-induced multiorgan dysfunction. The limitations of the experimental mice models to mimic the complexity of clinical MODS warrant further preclinical testing. In conclusion, our data suggest ferroptosis targeting as possible treatment option for a stratifiable subset of MODS patients.

Our findings indicate that the role of Sr in the development of bone lesions in renal failure is complex and that, depending on the dose, the element may act via multiple pathways.

Because current rat models used to study chronic kidney disease (CKD)-related vascular calcification show consistent but excessive vascular calcification and chaotic, immeasurable, bone mineralization due to excessive bone turnover, they are not suited to study the bone-vascular axis in one and the same animal. Because vascular calcification and bone mineralization are closely related to each other, an animal model in which both pathologies can be studied concomitantly is highly needed. CKD-related vascular calcification in rats was induced by a 0.25% adenine/low vitamin K diet. To follow vascular calcification and bone pathology over time, rats were killed at weeks 4, 8, 10, 11, and 12. Both static and dynamic bone parameters were measured. Vascular calcification was quantified by histomorphometry and measurement of the arterial calcium content. Stable, severe CKD was induced along with hyperphosphatemia, hypocalcemia as well as increased serum PTH and FGF23. Calcification in the aorta and peripheral arteries was present from week 8 of CKD onward. Four and 8 weeks after CKD, static and dynamic bone parameters were measurable in all animals, thereby presenting typical features of hyperparathyroid bone disease. Multiple regression analysis showed that the eroded perimeter and mineral apposition rate in the bone were strong predictors for aortic calcification. This rat model presents a stable CKD, moderate vascular calcification, and quantifiable bone pathology after 8 weeks of CKD and is the first model that lends itself to study these main complications simultaneously in CKD in mechanistic and intervention studies.

In this study evidence is provided for the rapid development of a mineralization defect in strontium-loaded CRF rats, accompanied by a reduced osteoblast number, reduced PTH synthesis or secretion, and increased serum ALP levels. These effects can be rapidly reversed after withdrawal of the compound.