An Alizarin red-based assay of mineralization by adherent cells in culture: comparison with cetylpyridinium chloride extraction

Alizarin red S (ARS) staining has been used for decades to evaluate calcium-rich deposits by cells in culture. It is particularly versatile in that the dye can be extracted from the stained monolayer and assayed. This study describes a sensitive method for the recovery and semiquantification of ARS in a stained monolayer by acetic acid extraction and neutralization with ammonium hydroxide followed by colorimetric detection at 405 nm. This method was three times more sensitive than an older method involving cetylpyridinium chloride (CPC) extraction and resulted in a better signal to noise ratio, especially for weakly stained monolayers. The assay facilitates detailed inspection of mineralization by phase microscopy and semiquantification of the entire monolayer by extraction and quantification. The sensitivity of the assay is improved by the extraction of the calcified mineral at low pH and, since the mineral is already stained in a quantitative manner, there is no requirement for an additional colorimetric quantification step. Furthermore, the linear range is much wider than those of conventional assays for calcium, making dilutions of mineral extracts prior to measurement unnecessary. It has a wide range of potential uses including tumor characterization, mesenchymal stem cell evaluation, and osteogenic compound screening. Although more labor intensive than CPC extraction, the protocol is more sensitive and yields more reliable results for weakly mineralizing samples.

Dkk-1-derived Synthetic Peptides and Lithium Chloride for the Control and Recovery of Adult Stem Cells from Bone Marrow

It is established that human mesenchymal stem cells (hMSCs) from bone marrow are a source of osteoblast progenitors in vivo and under appropriate conditions, differentiate into osteoblasts ex vivo. Because hMSCs are recovered by iliac crest aspirate and enriched by virtue of their adherence to tissue culture plastic, the cells provide a convenient ex vivo model for the study of osteogenic tissue repair in an experimentally accessible system. Recent advances in the field of skeletal development and osteogenesis have demonstrated that signaling through the canonical wingless (Wnt) pathway is critical for the differentiation of progenitor cell lines into osteoblasts. Inhibition of such signals can predispose MSCs to cell cycle entry and inhibit osteogenesis. Here, we report that synthetic peptides derived from the second cysteine-rich domain of the canonical Wnt inhibitor Dickkopf-1 (Dkk-1) have utility in controlling the growth and recovery of hMSCs from bone marrow stroma. Three peptides corresponding to residues 217-269 in Dkk-1 were each found to enhance the proliferation of hMSCs in culture over 2 days. The most active peptide exhibited agonistic characteristics in that it ablated the proliferation lag observed when cultures of hMSCs receive fresh medium. It also reduced the expression of endogenous Dkk-1 (Gregory, C. A., Singh, H., and Prockop, D. J. (2003) J. Biol. Chem. 278, 28067-28078). When the cytosolic level of beta-catenin was elevated by addition of LiCl to cultures of hMSCs, the peptide also accelerated degradation of beta-catenin on withdrawal of lithium. A second peptide, corresponding to residues 184-204 had preferential and high affinity for hMSCs in the log phase of proliferation. Peptide overlay assays on hMSC lysates confirmed that the peptide bound to a 184-kDa protein corresponding to the molecular mass of LRP6. Cells recovered by this peptide had enhanced osteogenic potential but less chondrogenic potential compared with controls. Because Wnt antagonists increase the number of non-committed hMSCs in culture, they may be of use in increasing the rate of osseous wound healing in vivo by increasing the level of systemically migrating hMSCs. Therefore, such molecules could contribute to the development of a novel family of pharmaceutical agents for the improvement of the healing process in humans.

Malignant lymphoma of the uterine cervix

Three patients with primary malignant lymphoma of the uterine cervix are reported and the literature is reviewed. All of the patients in the current cases presented with irregular menstruation. Two patients were found to have diffuse histiocytic lymphoma, and one patient had diffuse mixed lymphoma. Histologic diagnosis was confirmed by outside expert pathologists in all cases. In spite of locally advanced disease according to FIGO's classification (Stage IVA-2 and Stage IIB-1), they responded well to external irradiation, and had control of tumor within the pelvis. All are alive at 13, 7, and 3 years, respectively, after the completion of irradiation. One patient developed disseminated disease 4.25 years after the completion of external irradiation, but was successfully treated with combination chemotherapy for 2 years, and is alive at 6.75 years after the completion of chemotherapy without disease. Review of the other 21 cases reported in the literature reveals that 14 were free of disease after treatment. The importance of distinguishing malignant lymphoma from undifferentiated carcinoma or sarcoma is emphasized since cervical malignant lymphoma can be successfully treated with irradiation in spite of locally advanced disease.

The content of phylloquinone (vitamin K1) in human milk, cows' milk and infant formula foods determined by high-performance liquid chromatography

Phylloquinone (2-methyl-3-phytyl-1,4-naphthoquinone) in human and cows' milk and in infant formula foods has been assayed by a method based on high-performance liquid chromatography (HPLC). The method has three chromatographic steps consisting of a preliminary purification of lipid extracts by conventional liquid chromatography, a further fractionation by semipreparative HPLC and a final analytical step by reversed-phase HPLC in which phylloquinone was resolved from the remaining contaminants and quantified by reference to an internal standard (phylloquinone 2,3-epoxide). The identity of the chromatographic peak ascribed to phylloquinone (vitamin K1) was established by mass spectrometry. Mature human milk from 20 lactating mothers gave a mean concentration of phylloquinone of 2.1 micrograms/liter, and colostrum from 9 mothers gave a mean value of 2.3 micrograms/liter. These levels in human milk were significantly lower than those found in either Friesian (holstein) cows' milk (mean 4.9 micrograms/liter) or unsupplemented infant formula foods containing only cows' milk fat (mean 4.2 micrograms/liter). The mean phylloquinone content of two unsupplemented infant formula foods containing only vegetable oils was 11.5 micrograms/liter. After an oral dose of 20 mg phylloquinone, the concentration of K1 in the breast milk of one mother rose to 140 micrograms/liter after 12 hours and at 48 hours was still about twice the average endogenous level of human milk.