Human Non-Hematopoietic CD271pos/CD140alow/neg Bone Marrow Stroma Cells Fulfill Stringent Stem Cell Criteria in Serial Transplantations

Human bone marrow contains a population of non-hematopoietic stromal stem/progenitor cells (BMSCs), which play a central role for bone marrow stroma and the hematopoietic microenvironment. However, the precise characteristics and potential stem cell properties of defined BMSC populations have not yet been thoroughly investigated. Using standard adherent colony-forming unit fibroblast (CFU-F) assays, we have previously shown that BMSCs were highly enriched in the nonhematopoietic CD271pos/CD140alow/neg fraction of normal adult human bone marrow. In this study, we demonstrate that prospectively isolated CD271pos/CD140alow/neg BMSCs expressed high levels of hematopoiesis supporting genes and signature mesenchymal and multipotency genes on a single cell basis. Furthermore, CD271pos/CD140alow/neg BMSCs gave rise to non-adherent sphere colonies (mesenspheres) with typical surface marker profile and trilineage in vitro differentiation potential. Importantly, serial transplantations of CD271pos/CD140alow/neg BMSC-derived mesenspheres (single cell and bulk) into immunodeficient NOD scid gamma (NSG) mice showed increased mesensphere numbers and full differentiation potential after both primary and secondary transplantations. In contrast, BMSC self-renewal potential decreased under standard adherent culture conditions. These data therefore indicate that CD271pos/CD140alow/neg BMSCs represent a population of primary stem cells with MSC phenotype and sphere-forming capacity that fulfill stringent functional stem cell criteria in vivo in a serial transplantation setting

Isolation and characterization of primary bone marrow mesenchymal stromal cells

Bone marrow (BM) contains a rare population of mesenchymal stromal cells (MSCs), which have been characterized as nonhematopoietic skeletal progenitor cells with central importance for the hematopoietic microenvironment. Classically, MSCs are isolated by plastic adherence and subsequent culture. However, as cultured stromal cells differ from their in vivo progenitors, it is important to identify the phenotype of the primary MSCs to study these cells in more detail. In the past years, several surface markers have been reported to be suitable for effective enrichment of BM-MSCs, and recent data indicate that the putative MSC stem/progenitor cell population in human adult BM is highly enriched in Lin− CD45− CD271+ CD140a (PDGFRα)low/− cells. Moreover, surface marker combinations have been described for the isolation of MSCs from murine BM. On the basis of these findings, the role of primary MSCs can now be studied in normal and, importantly, diseased BM. Furthermore, genetically engineered mouse models have been developed as powerful tools to investigate well-defined BM stromal cell populations in vivo. Our discussion aims to provide a concise overview of the current state of the art in BM-MSC isolation in humans and briefly present murine MSC isolation approaches and genetic models

Human Primary Bone Marrow Mesenchymal Stromal Cells and Their in vitro Progenies Display Distinct Transcriptional Profile Signatures

Bone marrow mesenchymal stromal cells (BM-MSCs) are a rare population of cells that gives rise to skeletal tissues and the hematopoietic stroma in vivo. Recently, we have demonstrated that BM-MSCs fulfill stringent in vivo stem cell criteria when propagated as non-adherent mesenspheres but not as adherent-cultured cells. Motivated by these profound functional differences, the current study aimed to identify potential important MSC regulators by investigating global gene expression profiles of adherent and non-adherent culture-derived BM-MSCs in comparison with primary BM-MSCs. A substantial number of genes were differentially expressed between primary and culture-expanded cells already early upon culture, and numerous genes were found to be different when comparing adherent and non-adherent BM-MSCs. Cluster analysis identified 16 sets of genes of which two displayed comparable gene expression levels in primary and non-adherent cultured cells, but not in adherent cultured cells. This pattern suggested that these clusters contained candidate regulators of BM-MSCs. Gene expression differences were confirmed for selected genes and BM-MSC transcription factors by protein analysis and RT-PCR, respectively. Taken together, these data demonstrated profound gene expression changes upon culture of primary BM-MSCs. Moreover, gene cluster differences provide the basis to uncover the regulatory mechanisms that control primary and cultured BM-MSCs

Low/Negative Expression of PDGFR-α Identifies the Candidate Primary Mesenchymal Stromal Cells in Adult Human Bone Marrow

Human bone marrow (BM) contains a rare population of nonhematopoietic mesenchymal stromal cells (MSCs), which are of central importance for the hematopoietic microenvironment. However, the precise phenotypic definition of these cells in adult BM has not yet been reported. In this study, we show that low/negative expression of CD140a (PDGFR-α) on lin−/CD45−/CD271+ BM cells identified a cell population with very high MSC activity, measured as fibroblastic colony-forming unit frequency and typical in vitro and in vivo stroma formation and differentiation capacities. Furthermore, these cells exhibited high levels of genes associated with mesenchymal lineages and HSC supportive function. Moreover, lin−/CD45−/CD271+/CD140alow/− cells effectively mediated the ex vivo expansion of transplantable CD34+ hematopoietic stem cells. Taken together, these data indicate that CD140a is a key negative selection marker for adult human BM-MSCs, which enables to prospectively isolate a close to pure population of candidate human adult stroma stem/progenitor cells with potent hematopoiesis-supporting capacity

Effect of additives on the compressive strength of slag-based inorganic polymers

Summarization: The present paper aims to assess the effect of various additives on the compressive strength of inorganic polymers (geopolymers) synthesised using low Ca electric arc ferronickel slag and alkali activating solutions. The main operating parameters include pre-curing (48 hours), temperature (40 to 80 o C), heating time (24 or 48 h) and aging period (7 days). Addition of kaolinite, pozzolan, fly ash, red mud or CaO in the initial mixture has a detrimental effect on the final compressive strength. Addition of pulverised silica sand improves strength slightly, whereas addition of commercial glass results in strength values exceeding 60 MPa. XRD analysis was carried out to identify new formed phases and the degree of amorphicity, while SEM and element mapping analysis were used to identify the morphology of the final products as well as to elucidate to a certain degree the mechanisms involved in inorganic polymer synthesis.Παρουσιάστηκε στο: 2nd International Conference on Engineering for Waste Valorisatio

Geopolymerisation: A review and prospects for the minerals industry

Δημοσίευση σε επιστημονικό περιοδικόSummarization: Inorganic polymers, more commonly referred to as “geopolymers”, are alumino-silicate materials which exhibit excellent physical and chemical properties and a diverse range of potential applications, including precast structures and non-structural elements, concrete pavements and products, containment and immobilisation of toxic, hazardous and radioactive wastes, advanced structural tooling and refractory ceramics, and fire resistant composites used in buildings, aeroplanes, shipbuilding, racing cars, and the nuclear power industry. The current paper presents a brief history and a review of geopolymer technology, summarises and critically analyses the most important research findings over the last 25 years, attempts to elucidate chemistry and reaction mechanisms for the most important categories of materials involved, identifies the gaps in the existing body of knowledge and underlines the reasons why this promising technology after all these years of research has not become widely accepted by the industry. Finally the paper proposes further research and development topics and suggests steps forward to improve the potential of geopolymerisation, focusing on the utilisation of mining and metallurgical wastes and by-products, the synthesis of geopolymers with advanced properties and the stabilisation of hazardous wastes. It is strongly believed that geopolymerisation, when established as a viable technology and recognised by the industry, will contribute to the sustainable development of the minerals sector.Παρουσιάστηκε στο: Minerals Engineerin

Morphology of modified biochar and its potential for phenol removal from aqueous solutions

Summarization: In the present study, the efficiency of phenol removal from synthetic aqueous solutions by chemically modified biochar with the use of 1M KOH or 1M FeCl3 was investigated. Initially, biochar was produced after slow pyrolysis of three different agricultural wastes, namely pistachio (Pistacia vera L.) shells, pecan (Carya illinoinensis) shells, and wood sawdust. The quality of biochar was assessed by evaluating its main properties, such as pH, surface area, porosity and C content. X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Fourier Transform Infrared Spectroscopy (FTIR) were used for the identification of biochar's structure. The efficiency of phenol removal from synthetic solutions was assessed with the use of kinetic and equilibrium experiments. The experimental results show that the KOH-modified biochar exhibited the highest phenol removal efficiency. Hydrophobic sorption on its surface is the main phenol removal mechanism. The pseudo-second order model fits best the kinetic data, while the Freundlich model, as deduced from an equilibrium study describes very well sorption of phenols on all biochars examined.Presented on: Frontiers in Environmental Scienc