[Construction of urinary Tamm-Horsfall protein assay by enzyme-linked immunosorbent assay and establishment of reference range of healthy subject].

Tamm-Horsfall protein (THP) is the most abundant protein in the urine. THP is expressed in the renal tubule as a precursor protein having 640 amino acid residues and anchored by GPI anchor in the cell membrane. Thereafter, THP is secreted as a glycoprotein is a molecular weight of about 95-100 kD. Despite several investigations from the perspective of renal failure, the physiological role of this protein is not yet clear. It has been reported that THP is also related to certain conditions, such as kidney stone formation and urinary tract infection. To examine the excretion of THP into urine, we constructed an enzyme linked immunosorbent assay(ELISA) for the measurement of THP in the urine. THP was purified from healthy human urine using Diatomaceous Earth. Then we obtained an antibody to purified THP and constructed a sandwich ELISA assay system to test urine samples. The sensitivity of measurement was 0.78 ng/ml. In this assay, the concentration of THP in spot urine can be linearly measured from 0.78 ng/ml to 50 ng/ml. The CV of assay was 2.4 to 4.1%. The measurement was not disrupted by urinary albumin (approximately 15 mg/ml), hemoglobin (approximately 15 microg/ml), glucose (approximately 30 mg/ml) and ascorbic acid (approximately 10 mg/ml). Pretreatment by centrifugation or filtration of urine affected the concentration of THP because of the agglutinated form of THP. We showed that the urinary excretion rate remained almost constant in our test population, 1.00-1.65 mg/hr (average +/- 1SD 1.30 +/- 0.25) for healthy men and 0.61-1.51 mg/hr (0.90 +/- 0.30) for healthy women and 1.10 +/- 0.34 mg/hr overall.

Activation of the FGF signaling pathway and subsequent induction of mesenchymal stem cell differentiation by inorganic polyphosphate.

Inorganic polyphosphate [poly(P)] is a biopolymer existing in almost all cells and tissues, although its biological functions in higher eukaryotes have not been completely elucidated. We previously demonstrated that poly(P) enhances the function of fibroblast growth factors (FGFs) by stabilizing them and strengthening the affinity between FGFs and their cell surface receptors. Since FGFs play crucial roles in bone regeneration, we further investigated the effect of poly(P) on the cell differentiation of human stem cells via FGF signaling systems. Human dental pulp cells (HDPCs) isolated from human dental pulp show the characteristics of multipotent mesenchymal stem cells (MSCs). HDPCs secreted FGFs and the proliferation of HDPCs was shown to be enhanced by treatment with poly(P). Cell surface receptor-bound FGF-2 was stably maintained for more than 40 hours in the presence of poly(P). The phosphorylation of ERK1/2 was also enhanced by poly(P). The effect of poly(P) on the osteogenic differentiation of HDPCs and human MSCs (hMSCs) were also investigated. After 5 days of treatment with poly(P), type-I collagen expression of both cell types was enhanced. The C-terminal peptide of type-I collagen was also released at higher levels in poly(P)-treated HDPCs. Microarray analysis showed that expression of matrix metalloproteinase-1 (MMP1), osteopontin (OPN), osteocalcin (OC) and osteoprotegerin was induced in both cell types by poly(P). Furthermore, induced expression of MMP1, OPN and OC genes in both cells was confirmed by real-time PCR. Calcification of both cell types was clearly observed by alizarin red staining following treatment with poly(P). The results suggest that the activation of the FGF signaling pathway by poly(P) induces both proliferation and mineralization of stem cells.