Flow cytometric enumeration of CD34+ hematopoietic stem and progenitor cells in leukapheresis product and bone marrow for clinical transplantation: a comparison of three methods.

Flow cytometric enumeration of CD34+ hematopoietic stem and progenitor cells (HSCs) is widely used for evaluation of graft adequacy of peripheral blood and bone marrow stem cell grafts. In the present study, we review and compare the major counting techniques of stem and progenitor cells. The methods are: the Milan/Mullhouse protocol, two-platform ISHAGE (International Society of Hematotherapy and Graft Engineering) and single-platform ISHAGE analysis system. According to the Milan/Mulhouse protocol, HSCs are identified by CD34 antibody staining and easy gating strategy. The ISHAGE guidelines for detection of CD34+ cells are based on a four-parameter flow cytometry method (CD34PE/CD45PerCP staining, side and forward angle light scatter) thus employing multiparameter gating strategy. With two-platform ISHAGE protocol, an absolute CD34+ count is generated by incorporating the leukocyte count from an automated hematology analyser. The single-platform ISHAGE method to determine the absolute CD34+ count directly from a flow cytometer includes the use of Trucount tubes (Becton Dickinson) with a known number of fluorescent beads. CD34+ cells were quantified in mobilized peripheral blood, collected by leukapheresis, and bone marrow from 42 samples from patients with hematological malignancies. The differences against the means display low disagreement between the Milan/Mulhouse and ISHAGE protocols, with discrepancies of up to 2.5% (two-platform ISHAGE)--2.6% (single-platform ISHAGE) in enumeration of CD34+ cells in leukapheresis product and 4.8% (two-platform ISHAGE)--4.9% (single-platform ISHAGE) in bone marrow. Our results show high correlation among all three methods. Since the three protocols are compatible, choosing the most convenient in terms of costs, simplicity and compliance with clinical results appears to be a logical consequence

Meeting report: a hard look at the state of enamel research.

The Encouraging Novel Amelogenesis Models and Ex vivo cell Lines (ENAMEL) Development workshop was held on 23 June 2017 at the Bethesda headquarters of the National Institute of Dental and Craniofacial Research (NIDCR). Discussion topics included model organisms, stem cells/cell lines, and tissues/3D cell culture/organoids. Scientists from a number of disciplines, representing institutions from across the United States, gathered to discuss advances in our understanding of enamel, as well as future directions for the field

Structural Analysis of a Repetitive Protein Sequence Motif in Strepsirrhine Primate Amelogenin

Strepsirrhines are members of a primate suborder that has a distinctive set of features associated with the development of the dentition. Amelogenin (AMEL), the better known of the enamel matrix proteins, forms 90% of the secreted organic matrix during amelogenesis. Although AMEL has been sequenced in numerous mammalian lineages, the only reported strepsirrhine AMEL sequences are those of the ring-tailed lemur and galago, which contain a set of additional proline-rich tandem repeats absent in all other primates species analyzed to date, but present in some non-primate mammals. Here, we first determined that these repeats are present in AMEL from three additional lemur species and thus are likely to be widespread throughout this group. To evaluate the functional relevance of these repeats in strepsirrhines, we engineered a mutated murine amelogenin sequence containing a similar proline-rich sequence to that of Lemur catta. In the monomeric form, the MQP insertions had no influence on the secondary structure or refolding properties, whereas in the assembled form, the insertions increased the hydrodynamic radii. We speculate that increased AMEL nanosphere size may influence enamel formation in strepsirrhine primates

Amelogenin Nanoparticles in Suspension: Deviations from Spherical Shape and pH-Dependent Aggregation

It is well-known that amelogenin self-assembles to form nanoparticles, usually referred to as amelogenin nanospheres, despite the fact that not much is known about their actual shape in solution. In the current paper, we combine SAXS and DLS to study the three-dimensional shape of the recombinant amelogenins rP172 and rM179. Our results show for the first time that amelogenins build oblate nanoparticles in suspension using experimental approaches that do not require the proteins to be in contact with a support material surface. The SAXS studies give evidence for the existence of isolated amelogenin nano-oblates with aspect ratios in the range of 0.45-0.5 at pH values higher than pH 7.2 and show an aggregation of these nano-oblates at lower pH values. The role of the observed oblate shape in the formation of chain-like structures at physiological conditions is discussed as a key factor in the biomineralization of dental enamel

Amelogenin Supramolecular Assembly in Nanospheres Defined by a Complex Helix-Coil-PPII Helix 3D-Structure

Tooth enamel, the hardest material in the human body, is formed within a self-assembled matrix consisting mostly of amelogenin proteins. Here we have determined the complete mouse amelogenin structure under physiological conditions and defined interactions between individual domains. NMR spectroscopy revealed four major amelogenin structural motifs, including an N-terminal assembly of four α-helical segments (S9-V19, T21-P33, Y39-W45, V53-Q56), an elongated random coil region interrupted by two 310 helices (∼P60-Q117), an extended proline-rich PPII-helical region (P118-L165), and a charged hydrophilic C-terminus (L165-D180). HSQC experiments demonstrated ipsilateral interactions between terminal domains of individual amelogenin molecules, i.e. N-terminal interactions with corresponding N-termini and C-terminal interactions with corresponding C-termini, while the central random coil domain did not engage in interactions. Our HSQC spectra of the full-length amelogenin central domain region completely overlapped with spectra of the monomeric Amel-M fragment, suggesting that the central amelogenin coil region did not involve in assembly, even in assembled nanospheres. This finding was confirmed by analytical ultracentrifugation experiments. We conclude that under conditions resembling those found in the developing enamel protein matrix, amelogenin molecules form complex 3D-structures with N-terminal α-helix-like segments and C-terminal PPII-helices, which self-assemble through ipsilateral interactions at the N-terminus of the molecule

Norovirus infections in children under 5 years of age hospitalized due to the acute viral gastroenteritis in northeastern Poland

The primary aim of this study was to evaluate the frequency and seasonality of norovirus infection in hospitalized Polish children under 5 years of age, and a secondary aim was to compare the clinical severity of norovirus and rotavirus disease. The prospective surveillance study was carried out from July 2009 through June 2010. Stool samples from 242 children hospitalized due to acute viral gastroenteritis were tested for rotavirus group A and adenovirus with commercial immunochromatographic test and for norovirus with EIA assay. Single norovirus infection was found in 35/242 (14.5%) patients and in a further 5 (2.1%) children as co-infection with rotavirus. Overall, norovirus was detected in 16.5% of stool specimens. Norovirus infections tended to peak from October to November and again from February to March. In autumn months and in February, the proportion of norovirus gastroenteritis cases was equal or even surpassed those of rotavirus origin. Both norovirus and rotavirus infections most commonly affected children between 12 and 23 months of age. The low-grade or no fever was significantly more common in children infected with norovirus (94.3%) compared to rotavirus cases (52.9%). Overall, norovirus gastroenteritis was less severe than rotavirus disease with regard to 20-point severity scale (p < 0.05). Noroviruses have emerged as a relevant cause of acute gastroenteritis in Polish children. There is a great need for introducing routine norovirus testing of hospitalized children with gastroenteritis

Relationship of Dental Caries and Fluorosis to Fluoride Supplement History in a Non-Fluoridated Sample of Schoolchildren

A random sample of 206 Michigan children, aged from 9 to 13, were examined for fluorosis from a larger group of 2038 children participating in a dental project. Clinical examinations included caries data (DMFS) and assessment of fluorosis by use of the Tooth Surface Index of Fluorosis (TSIF). Separate examiners were used for each index. The response rate of a questionnaire mailed to parents to gather information on residence histories, use of fluoride supplements, and antibiotics was 78%. The prevalence of fluorosis was about 20% among the respondents. Of the 4868 tooth surfaces examined, 9.2% were affected by fluorosis. In all cases, dental fluorosis was judged as mild, with most occurrences on the posterior teeth. No instances of moderate or severe fluorosis were found. The caries experience of respondents was 1.69 ± 2.73 DMFS. Caries experience does not appear to be significantly related to income, education, or fluoride supplement use. Approximately 52% of respondents were reported to have taken fluoride supplements with various degrees of consistency. Parents' education was positively related to both prevalence of fluorosis (odds ratio = 2.2) and use of fluoride supplements (odds ratio = 2.7). No significant relation was revealed with evidence of fluorosis and use of supplements. This study shows a relatively mild level of dental fluorosis in a sample of children from a non-fluoridated area. Dental fluorosis in this group does not appear to be related to use of fluoride supplements or differences in caries experience.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66503/2/10.1177_08959374890030021501.pd

Cementomimetics—constructing a cementum-like biomineralized microlayer via amelogenin-derived peptides

This is the published version. Copyright 2012 Nature Publishing GroupCementum is the outer-, mineralized-tissue covering the tooth root and an essential part of the system of periodontal tissue that anchors the tooth to the bone. Periodontal disease results from the destructive behavior of the host elicited by an infectious biofilm adhering to the tooth root and left untreated, may lead to tooth loss. We describe a novel protocol for identifying peptide sequences from native proteins with the potential to repair damaged dental tissues by controlling hydroxyapatite biomineralization. Using amelogenin as a case study and a bioinformatics scoring matrix, we identified regions within amelogenin that are shared with a set of hydroxyapatite-binding peptides (HABPs) previously selected by phage display. One 22-amino acid long peptide regions referred to as amelogenin-derived peptide 5 (ADP5) was shown to facilitate cell-free formation of a cementum-like hydroxyapatite mineral layer on demineralized human root dentin that, in turn, supported attachment of periodontal ligament cells in vitro. Our findings have several implications in peptide-assisted mineral formation that mimic biomineralization. By further elaborating the mechanism for protein control over the biomineral formed, we afford new insights into the evolution of protein–mineral interactions. By exploiting small peptide domains of native proteins, our understanding of structure–function relationships of biomineralizing proteins can be extended and these peptides can be utilized to engineer mineral formation. Finally, the cementomimetic layer formed by ADP5 has the potential clinical application to repair diseased root surfaces so as to promote the regeneration of periodontal tissues and thereby reduce the morbidity associated with tooth loss

Elongated Polyproline Motifs Facilitate Enamel Evolution through Matrix Subunit Compaction

How does proline-repeat motif length in the proteins of teeth and bones relate to the evolution of vertebrates? Counterintuitively, longer repeat stretches are associated with smaller aggregated subunits within a supramolecular matrix, resulting in enhanced crystal length in mammalian versus amphibian tooth enamel