Biochemical bone markers, bone mineral content, and bone mineral density in rats with experimental nephrotic syndrome

Effects of icariin on the proliferation and osteogenic differentiation of human amniotic mesenchymal stem cells

Background

Tissue engineering technology has been applied extensively for clinical research and human amnion mesenchymal stem cells (hAMSCs) could cause mesenchymal stem cells to differentiate into the bone tissue. However, it is necessary to develop and identify the safer appropriate amount of osteogenic inducer. The objective of this study is to investigate the effect of icariin (ICA) on the proliferation and osteogenic differentiation of hAMSCs.

Methods

The morphology and phenotype of hAMSCs were discovered by flow cytometry and immunocytochemical staining. The osteogenic differentiation of hAMSCs under the influence of different concentrations of ICA were assessed by alkaline phosphatase (ALP) activity substrate assay and alizarin red staining.

Results

MTT assay revealed that the hAMSCs pretreated with ICA exhibited increased proliferation when compared with the control group, and the most optimum concentration of ICA was 1 × 10^− 6 mol/L. The combined analysis of ALP activity and ARS staining showed that ICA could significantly promote the osteogenic differentiation of hAMSCs, and the effect was most significant when the concentration of ICA was 1 × 10^− 6 mol/L.

Conclusion

All the above results implied that ICA could significantly increase proliferation and enhance the osteogenic differentiation of hAMSCs, especially when the concentration of ICA was 1 × 10^− 6 mol/L.

A novel CPC composite cement reinforced by dopamine coated SCPP fibers with improved physicochemical and biological properties

Traditional CPC cements have attracted wide attentions in repairing bone defects for injectability, easy plasticity and good osseointegration. However, its further application was limited by poor mechanical properties, long setting time and unsatisfactory biocompatibility. To solve these problems, polydopamine (DOPA) coated strontium-doped calcium polyphosphate (SCPP) fibers were added into CPC cements for the first time. A doping amount at fiber weight fraction of 0%, 1%, 2% and 5% was designed to develop a multifunctional composite fitting for bone tissues' regeneration and reconstruction and the optimum amount was selected through subsequent physicochemical and biological characterizations. The results implied DOPA coating successfully formed stable connections between SCPP fibers and CPC matrix, which simultaneously reinforced biomechanical strength and tenacity (5% SCPP/D/CPC samples exhibited more prominent mechanical property than others). In addition, 5% D/SCPP fibers doped composite cements were characterized as markedly-improved cytocompatibility: Sr²⁺ introduction induced cytoactive and significantly accelerated proliferation, attachment and spreading of osteoblasts. Besides, it also stimulated the secretion of OT, Col-I and ALP from seeded MG63, which was a critical character for further inducing osteogenic process, mineralization and bone tissues formation. The promoted cytocompatibility and improved osteogenesis-related growth factors' secretion could be attributed to constant and controllable release of Sr²⁺ and this deduction was approved by ICP analysis. In addition, Sr doping made this novel cement had a potential efficacy to inhibit aseptic loosening. In a word, present studies all demonstrated 5% SCPP/D/CPC composites could be a potential candidate material employed in bone regeneration and reconstruction for excellent mechanical property and cytocompatibility.

Ginsenoside Rg1 promotes osteogenic differentiation of rBMSCs and healing of rat tibial fractures through regulation of GR-dependent BMP-2/SMAD signaling

Fracture healing is closely related to the number and activity of bone marrow mesenchymal stem cells (BMSCs) near the fracture site. The present study was to investigate the effect of Rg1 on osteogenic differentiation of cultured BMSCs and related mechanisms and on the fracture healing in a fracture model. In vitro experiments showed that Rg1 promoted the proliferation and osteogenic differentiation of BMSCs. Western blot analyses demonstrated that Rg1 promoted osteogenic differentiation of BMSCs through the glucocorticoid receptor (GR)-dependent BMP-2/Smad signaling pathway. In vivo, X-ray examination showed that callus growth in rats treated with Rg1 was substantially faster than that in control rats after fracture. The results of H&E and Safranin-O/Fast Green staining revealed that, compared with controls, rats in the Rg1 treatment group had a significantly higher proportion of trabecular bone but a much lower proportion of fibers and cartilage components inside the callus. Micro-CT suggested that bone mineral density (BMD), percent bone volume (BV/TV), trabecular number (Tb.N), and trabecular thickness (Tb.Th) were significantly increased in the treatment group, whereas trabecular separation (Tb.Sp) was significantly reduced. Thus, Rg1 promotes osteogenic differentiation by activating the GR/BMP-2 signaling pathway, enhances bone calcification, and ultimately accelerates the fracture healing in rats.

Use of iQPR-H₂O for bone regeneration and its potential in the improvement of osteoporosis

Background

Current treatments for osteoporosis are associated with various side effects and do not prevent the age-related decrease in osteoblast number. The objective of this study was to evaluate the effects of iQPR-H₂O on osteogenesis.

Methods

Mouse fibroblast NIH3T3 and pre-osteoblastic MC3T3-E1 cells were cultured in medium prepared with iQPR-H₂O or unprocessed mineral water (control cells), and proliferation and differentiation were assessed by MTT and alkaline phosphatase assay, respectively. Mineral deposition by the cells was determined using Alizarin red S staining. A mouse model of osteoporosis, ovariectomized SAMP8 mice, was used to evaluate the effects of iQPR-H₂O on osteogenesis in vivo. Mice were given either iQPR-H₂O or unprocessed mineral water (control group) for four months after which bone mass density (BMD) measurements were made using a bone densitometer and hematoxylin and eosin staining of bone samples.

Results

NIH3T3 cells grown in medium prepared with iQPR-H₂O exhibited significantly greater proliferation. NIH3T3 and MC3T3-E1 cells demonstrated a significant increase in alkaline phosphatase levels in the iQPR-H₂O group. MC3T3-E1 cells showed mineralization at day 28. mRNA expression levels of both osteopontin and runt-related transcription factor 2 in MC3T3-E1 cells were higher in the iQPR-H₂O group compared with the control group. After four months, significantly greater bone regeneration was evident in ovariectomized SAMP8 mice administered iQPR-H₂O as compared with control group.

Conclusions

iQPR-H₂O may reduce the symptoms of osteoporosis by improving osteogenesis.

Prophylactic calcium and vitamin D treatments in steroid-treated children with nephrotic syndrome

Steroid treatment has several side effects, including the deterioration of the bone and mineral metabolism in children with nephrotic syndrome. This randomized prospective study was conducted to determine the effects and prophylactic role of calcium plus vitamin D treatment on bone and mineral metabolism in children receiving prednisolone treatment. 40 children (27 boys and 13 girls) with NS (18 new onset and 22 relapsing) were included in the study. Their mean age was 4.6+/-1.8 years. All patients received prednisolone treatment (2 mg/kg/day for 4 weeks followed by alternate days at the same dose for 4 weeks). The patients were randomized into treatment (vitamin D 400 IU plus calcium 1 g daily) and non-treatment groups. Bone mineral density, serum Ca, P, alkaline phosphatase and urinary Ca and P excretions were analyzed at the beginning and 2 months after the treatment. The XR36 Norland device was used for bone mineral density analysis. Bone mineral density was significantly decreased in both the treatment (0.54+/-0.15 to 0.51+/-0.1 g/cm(2), P =0.001) and non-treatment (0.52+/-0.18 to 0.45+/-0.16 g/cm(2), P <0.001) group. But the percentage of bone mineral density decrease was found to be significantly lower in the treatment group than in the non-treatment group (4.6+/-2.1% vs. 13.0+/-4.0%, respectively; P <0.001). Serum calcium and urinary calcium excretion increased in the treatment group (8.0+/-1.0 to 10.0+/-0.5 mg/dl and 1.1+/-0.5 to 3.2+/-1.0 mg/kg/day) and non-treatment group (8.1+/-0.8 to 10.0+/-0.6 mg/dl and 1.4+/-0.9 to 3.8+/-3.3 mg/kg/day) after prednisolone treatment (P <0.001). Steroid treatment decreases bone mineral density in children with nephrotic syndrome. Vitamin D plus calcium therapy at the current doses reduces but does not completely prevent bone loss, with no additional adverse effects.

Oim mice exhibit altered femur and incisor mineral composition and decreased bone mineral density

To investigate the role of the pro alpha 2(I) collagen chains of type I collagen in mineralization we used the oim (osteogenesis imperfecta model) mouse as our model system. The oim/oim mouse (homozygous for a null mutation in its COL1A2 gene of type I collagen) fails to synthesize functional pro alpha 2(I) collagen chains, synthesizing only homotrimers of pro alpha 1(I) collagen chains. To evaluate the role of pro alpha 2(I) collagen in type I collagen structure/function in mineralized tissues, we examined age-matched oim/oim, heterozygous (oim/+), and wild-type (+/+) mouse femurs and incisors for mineral composition (calcium, phosphorus, magnesium, fluoride, sodium, potassium, and chloride) by neutron activation analyses (NAA), and bone mineral content (BMC) and bone mineral density (BMD) by dual-energy X-ray absorptiometry (DEXA) in a longitudinal study (7 weeks to 16 months of age). NAA demonstrated that oim/oim femurs had significant differences in magnesium, fluoride, and sodium content as compared with +/+ mouse femurs, and oim/oim teeth had significant differences in magnesium content as compared to +/+ teeth. The ratio of calcium to phosphate was also significantly reduced in the oim/oim mouse femurs (1.58 +/- 0.01) compared with +/+ femurs (1.63 +/- 0.01). DEXA demonstrated that oim/oim mice had significantly reduced BMC and BMD as compared to oim/+ and +/+ mice. Serum and urine calcium, magnesium, and phosphorus levels, and Ca(47) absorption across the gut were equivalent in oim/oim and +/+ mice, with no evidence of hypercalciuria. These studies suggest that the known decreased biomechanical properties of oim/oim bone reflect both altered mineral composition as well as the decreased BMD, which further suggests that the presence of alpha2(I) chains plays an important role in mineralization.

Tissue distribution of alpha-tocopherol in nephrotic rats

1. Reactive oxygen species are involved in the pathogenesis of puromycin aminonucleoside (PAN) nephrosis and alpha-tocopherol is one of the major anti-oxidants in the body. 2. In the present study, we measured the levels of alpha-tocopherol by high-performance liquid chromatography in the plasma and in nine tissues of control and nephrotic rats obtained 10 days after either 0.9% saline solution or PAN injection, respectively. 3. In nephrotic rats, alpha-tocopherol levels increased four-fold in plasma; however, the molar ratio of alpha-tocopherol/ cholesterol remained unchanged, suggesting that the increase in alpha-tocopherol content was attributable to an increase in plasma lipid concentration. 4. In nephrotic rats, the alpha-tocopherol/cholesterol ratio increased 1.33-fold in adrenal glands and 1.34-fold in the testis, but remained unchanged in heart, spleen, liver, kidney lung, brain and muscle. 5. These data suggest that, in PAN nephrotic rats, there are alterations in the distribution of alpha-tocopherol and there is no deficiency of alpha-tocopherol in plasma or tissues.