Effect of Npt2b deletion on intestinal and renal inorganic phosphate (Pi) handling.

BACKGROUND: Hyperphosphatemia is common in chronic kidney disease and is associated with morbidity and mortality. The intestinal Na+-dependent phosphate transporter Npt2b is thought to be an important molecular target for the prevention of hyperphosphatemia. The role of Npt2b in the net absorption of inorganic phosphate (Pi), however, is controversial. METHODS: In the present study, we made tamoxifen-inducible Npt2b conditional knockout (CKO) mice to analyze systemic Pi metabolism, including intestinal Pi absorption. RESULTS: Although the Na+-dependent Pi transport in brush-border membrane vesicle uptake levels was significantly decreased in the distal intestine of Npt2b CKO mice compared with control mice, plasma Pi and fecal Pi excretion levels were not significantly different. Data obtained using the intestinal loop technique showed that Pi uptake in Npt2b CKO mice was not affected at a Pi concentration of 4 mM, which is considered the typical luminal Pi concentration after meals in mice. Claudin, which may be involved in paracellular pathways, as well as claudin-2, 12, and 15 protein levels were significantly decreased in the Npt2b CKO mice. Thus, Npt2b deficiency did not affect Pi absorption within the range of Pi concentrations that normally occurs after meals. CONCLUSION: These findings indicate that abnormal Pi metabolism may also be involved in tight junction molecules such as Cldns that are affected by Npt2b deficiency.

Acute and temporal expression of tumor necrosis factor (TNF)-α-stimulated gene 6 product, TSG6, in mesenchymal stem cells creates microenvironments required for their successful transplantation into muscle tissue.

Previously, we demonstrated that when mesenchymal stem cells (MSCs) from mouse ES cells were transplanted into skeletal muscle, more than 60% of them differentiated into muscles in the crush-injured tibialis anterior muscle in vivo, although MSCs neither differentiated nor settled in the intact muscle. Microenvironments, including the extracellular matrix between the injured and intact muscle, were quite different. In the injured muscle, hyaluronan (HA), heavy chains of inter-α-inhibitor (IαI), CD44, and TNF-α-stimulated gene 6 product (TSG-6) increased 24-48 h after injury, although basement membrane components of differentiated muscle such as perlecan, laminin, and type IV collagen increased gradually 4 days after the crush. We then investigated the microenvironments crucial for cell transplantation, using the lysate of C2C12 myotubules for mimicking injured circumstances in vivo. MSCs settled in the intact muscle when they were transplanted together with the C2C12 lysate or TSG6. MSCs produced and released TSG6 when they were cultured with C2C12 lysates in vitro. MSCs pretreated with the lysate also settled in the intact muscle. Furthermore, MSCs whose TSG6 was knocked down by shRNA, even if transplanted or pretreated with the lysate, could not settle in the muscle. Immunofluorescent staining showed that HA and IαI always co-localized or were distributed closely, suggesting formation of covalent complexes, i.e. the SHAP-HA complex in the presence of TSG6. Thus, TSG6, HA, and IαI were crucial factors for the settlement and probably the subsequent differentiation of MSCs.

Predictive factors for the outcome of multidisciplinary treatments in chronic low back pain at the first multidisciplinary pain center of Japan.

[Purpose] Multidisciplinary treatments are recommended for treatment of chronic low back pain. The aim of this study was to show the associations among multidisciplinary treatment outcomes, pretreatment psychological factors, self-reported pain levels, and history of pain in chronic low back pain patients. [Subjects and Methods] A total of 221 chronic low back pain patients were chosen for the study. The pretreatment scores for the 10-cm Visual Analogue Scale, Hospital Anxiety and Depression Scale, Pain Catastrophizing Scale, Short-Form McGill Pain Questionnaire, Pain Disability Assessment Scale, pain drawings, and history of pain were collected. The patients were divided into two treatment outcome groups a year later: a good outcome group and a poor outcome group. [Results] One-hundred eighteen patients were allocated to the good outcome group. The scores for the Visual Analogue Scale, Pain Disability Assessment Scale, and affective subscale of the Short-Form McGill Pain Questionnaire and number of nonorganic pain drawings in the good outcome group were significantly lower than those in the poor outcome group. Duration of pain in the good outcome group was significantly shorter than in the poor outcome group. [Conclusion] These findings help better predict the efficacy of multidisciplinary treatments in chronic low back pain patients.

Phosphaturic mesenchymal tumor, mixed connective tissue type, non-phosphaturic variant: report of a case and review of 32 cases from the Japanese published work.

Phosphaturic mesenchymal tumor, mixed connective tissue type (PMTMCT) is a rare neoplasm that can cause tumor-induced osteomalacia due to overproduction of a phosphaturic hormone, fibroblast growth factor 23 (FGF23). We report here a case of subcutaneous PMTMCT, non-phosphaturic variant, in the sole. We also review 32 Japanese cases of PMTMCT reported in detail. They occurred in 16 men and 15 women (one was unknown), with ages ranging 20-73 years (median, 48). Tumors were found in soft tissue, bone and sinuses in 17, 11 and four, respectively. A history of long-standing osteomalacia was noted in all cases except two non-phosphaturic variant cases. Serum FGF23 level was elevated in 11 of 12 cases examined. In terms of follow-up information, metastases were found in four patients, and two patients died of disease. In conclusion, PMTMCT is histologically a benign lesion; however, there may be rare metastatic and malignant cases. Wider recognition of the histological features of this unique neoplasm would aid its distinction from the large number of mesenchymal tumors for which it may be mistaken and should enable correct diagnosis of tumors with osteomalacia.

Generation of rat-induced pluripotent stem cells from a new model of metabolic syndrome.

We recently characterized DahlS.Z-Leprfa/Leprfa (DS/obese) rats, derived from a cross between Dahl salt-sensitive rats and Zucker rats, as a new animal model of metabolic syndrome (MetS). Although the phenotype of DS/obese rats is similar to that of humans with MetS, the pathophysiological and metabolic characteristics in each cell type remain to be clarified. Hence, the establishment of induced pluripotent stem cells (iPSCs) derived from MetS rats is essential for investigations of MetS in vitro. Reports of rat iPSCs (riPSCs), however, are few because of the difficulty of comparing to other rodents such as mouse. Recently, the advantage of using mesenchymal stromal cells (MSCs) as a cell source for generating iPSCs was described. We aimed to establish riPSCs from MSCs in adipose tissues of both DS/obese rats and their lean littermates, DahlS.Z-Lepr+/Lepr+ (DS/lean) rats using lentivirus vectors with only three factors Oct4, Klf4, and Sox2 without c-Myc. The morphology, gene expression profiles, and protein expression of established colonies showed embryonic stem cell (ESCs)-like properties, and the differentiation potential into cells from all three germ layers both in vitro and in vivo (teratomas). Both riPSCs became adipocytes after induction of adipogenesis by insulin, T3, and dexamethasone. Real-time PCR analysis also revealed that both riPSCs and the adipose tissue from DS/obese and DS/lean rats possess similar expression patterns of adipocyte differentiation-related genes. We succeeded in generating riPSCs effectively from MSCs of both DS/obese and DS/lean rats. These riPSCs may well serve as highly effective tools for the investigation of MetS pathophysiology in vitro.

Transplantated mesenchymal stem cells derived from embryonic stem cells promote muscle regeneration and accelerate functional recovery of injured skeletal muscle.

We previously established that mesenchymal stem cells originating from mouse embryonic stem (ES) cells (E-MSCs) showed markedly higher potential for differentiation into skeletal muscles in vitro than common mesenchymal stem cells (MSCs). Further, the E-MSCs exhibited a low risk for teratoma formation. Here we evaluate the potential of E-MSCs for differentiation into skeletal muscles in vivo and reveal the regeneration and functional recovery of injured muscle by transplantation. E-MSCs were transplanted into the tibialis anterior (TA) muscle 24 h following direct clamping. After transplantation, the myogenic differentiation of E-MSCs, TA muscle regeneration, and re-innervation were morphologically analyzed. In addition, footprints and gaits of each leg under spontaneous walking were measured by CatWalk XT, and motor functions of injured TA muscles were precisely analyzed. Results indicate that >60% of transplanted E-MSCs differentiated into skeletal muscles. The cross-sectional area of the injured TA muscles of E-MSC-transplanted animals increased earlier than that of control animals. E-MSCs also promotes re-innervation of the peripheral nerves of injured muscles. Concerning function of the TA muscles, we reveal that transplantation of E-MSCs promotes the recovery of muscles. This is the first report to demonstrate by analysis of spontaneous walking that transplanted cells can accelerate the functional recovery of injured muscles. Taken together, the results show that E-MSCs have a high potential for differentiation into skeletal muscles in vivo as well as in vitro. The transplantation of E-MSCs facilitated the functional recovery of injured muscles. Therefore, E-MSCs are an efficient cell source in transplantation.