Molecular and functional characterization of human bone marrow adipocytes

Adipocytes are a cell population largely located in the human bone marrow cavity. In this specific microenvironment where adipocytes can interact with a variety of different cells, the role of fat is mainly unknown. To our knowledge, this report is the first to characterize mature adipocytes isolated from human bone marrow (BM-A) molecularly and functionally to better understand their roles into the hematopoietic microenvironment. Healthy BM-A were isolated after collagenase digestion and filtration. We studied the morphology of BM-A, their gene expression and immunophenotypic profile and their functional ability in the hematopoietic microenvironment, comparing them with adipocytes derived from adipose tissue (AT-A). BM-A showed a unilocular lipid morphology similar to AT-A and did not lose their morphology in culture; they showed a comparable pattern of stem cell-surface antigens to AT-A. In line with these observations, molecular data showed that BM-A expressed some embryonic stem cells genes, such as Oct4, KLf4, c-myc, Gata4, Tbx1, and Sox17, whereas they did not express the stem cell markers Sox2 and Nanog. Moreover, BM-A had long telomeres that were similar to bone marrow mesenchymal stem cells. Notably, BM-A supported the survival and differentiation of hematopoietic stem cells in long-term cultures. These results showed that BM-A are stromal cells with a gene expression pattern that distinguished them from AT-A. BM-A showed stem cell properties through their hematopoietic supporting function, which was certainly linked to their role in the maintenance of the bone marrow microenvironment. Depending on specific demands, BM-A may acquire different functions based on their local environment.

Cadmium, lead, and chromium in large game: a local-scale exposure assessment for hunters consuming meat and liver of wild boar

Heavy metals are ubiquitous in soil, water, and air. Their entrance into the food chain is an important environmental issue that entails risks to humans. Several reports indicate that game meat can be an important source of heavy metals, particularly because of the increasing consumption of game meat, mainly by hunters. We performed an exposure assessment of hunters and members of their households, both adults and children, who consumed wild boar (WB) meat and offal. We estimated the amount of cadmium, lead, and chromium in the tissues of WB hunted in six areas within Viterbo Province (Italy) and gathered data on WB meat and offal consumption by conducting specific diet surveys in the same areas. The exposure to cadmium, lead, and chromium was simulated with specifically developed Monte Carlo simulation models. Cadmium and lead levels in WB liver and meat harvested in Viterbo Province (Italy) were similar to or lower than the values reported in other studies. However, some samples contained these metals at levels greater then the EU limits set for domestic animals. The chromium content of meat or liver cannot be evaluated against any regulatory limit, but our results suggest that the amounts of this metal found in WB products may reflect a moderate environmental load. Our survey of the hunter population confirmed that their consumption of WB meat and liver was greater than that of the general Italian population. This level of consumption was comparable with other European studies. Consumption of WB products contributes significantly to cadmium and lead exposure of both adults and children. More specifically, consumption of the WB liver contributed significantly to total cadmium and lead exposure of members of the households of WB hunters. As a general rule, liver consumption should be kept to a minimum, especially for children living in these hunter households. The exposure to chromium estimated for this population of hunters may be considered to be safe. However, a specific and complete assessment of chromium speciation in relevant dietary and environmental situations should be conducted.

Human dedifferentiated adipocytes show similar properties to bone marrow-derived mesenchymal stem cells

Mature adipocytes are generally considered terminally differentiated because they have lost their proliferative abilities. Here, we studied the gene expression and functional properties of mature adipocytes isolated from human omental and subcutaneous fat tissues. We also focused on dedifferentiated adipocytes in culture and their morphologies and functional changes with respect to mature adipocytes, stromal-vascular fraction (SVF)-derived mesenchymal stem cells (MSCs) and bone marrow (BM)-derived MSCs. Isolated mature adipocytes expressed stem cell and reprogramming genes. They replicated in culture after assuming a fibroblast-like shape and expanded similarly to SVF- and BM-derived MSCs. During the dedifferentiation process, mature adipocytes lost their lineage gene expression profile, assumed the typical mesenchymal morphology and immunophenotype, expressed stem cell genes and differentiated into multilineage cells. Moreover, during the dedifferentiation process, we showed changes in the epigenetic status of mature adipocytes, which led dedifferentiated adipocytes to display a similar DNA methylation condition to BM-derived MSCs. Like SVF- and BM-derived MSCs, dedifferentiated adipocytes were able to inhibit the proliferation of stimulated lymphocytes in coculture while mature adipocytes stimulated their growth. Furthermore, dedifferentiated adipocytes maintained the survival and complete differentiation characteristic of hematopoietic stem cells. This is the first study that in addition to characterizing isolated and dedifferentiated adipocytes also reports on the immunoregulatory and hematopoietic supporting functions of these cells. This structural and functional characterization might have clinical applications of both mature and dedifferentiated adipocytes in such fields, as regenerative medicine.

Human AB serum for generation of mesenchymal stem cells from human chorionic villi: comparison with other source and other media including platelet lysate

OBJECTIVES

We have investigated foetal mesenchymal stem cells (MSCs) obtained from first-trimester chorionic villi (CV) and second-trimester amniotic fluid (AF), comparing them to adult bone marrow-derived MSCs.

MATERIALS AND METHODS

We report on cell population growth in human allogeneic serum (HS) and platelet lysate (PL), immunophenotype, cytokine expression profile and immunoregulatory activity, of these foetal MSCs on stimulated peripheral blood mononuclear and lymphocyte subpopulations.

RESULTS

Chorionic villi cells grow rapidly in HS, with 20 populations doublings (PDs) after 59 days (six passages), and also in animal serum, with 27 PDs after 65 days (seven passages). PL allowed for expansion in 60% of the samples tested, although it was lower than in HS. HS supported an average of 40 PDs of expansion in 20% of AF cells after 90 days, whereas animal serum supported 28.5 PDs in 66 days. CV and AF cells inhibited proliferation of stimulated T lymphocytes, suppressing population growth of both CD4+ and CD8+ T subpopulations and sometimes also, CD19+ cells.

CONCLUSIONS

Our results indicate that CV would be an optimal source of MSCs with high expansion potential in a HS propagation system and immunoregulatory capacity of T and B lymphocytes. More than 90% of CV samples achieved large-scale expansion in HS, which is encouraging for potential clinical applications of these cells.

Human Mesenchymal Stem Cells from Chorionic Villi and Amniotic Fluid are not Susceptible to Transformation after Extensive in Vitro Expansion

Mesenchymal stem cells (MSCs) are promising candidates for cell therapy and tissue engineering. Increasing evidence suggests that MSCs isolated from fetal tissues are more plastic and grow faster than adult MSCs. In this study, we characterized human mesenchymal progenitor cells from chorionic villi (CV) and amniotic fluid (AF) isolated during the first and second trimesters, respectively, and compared them with adult bone marrow-derived MSCs (BM). We evaluated 10 CV, 10 AF, and 6 BM samples expanded until the MSCs reached senescence. We used discarded cells from prenatal analyses for all the experiments. To evaluate the replicative stability of these cells, we studied the telomerase activity, hTERT gene transcription, and telomere length in these cells. Spontaneous chromosomal alterations were excluded by cytogenetic analysis. We studied the expression of c-myc and p53, tumor-associated genes, at different passage in culture and the capacity of these cells to grow in an anchorage-independent manner by using soft agar assay. We isolated homogeneous populations of spindle-shaped CV, AF, and BM cells expressing mesenchymal immunophenotypic markers throughout the period of expansion. CV cells achieved 14 ± 0.9 logs of expansion in 118 days and AF cells achieved 21 ± 0.9 logs in 118 days, while BM cells achieved 11 × 0.4 logs in 84 days. Despite their high proliferation capacity, fetal MSCs showed no telomerase activity, no hTERT and c-myc transcriptions, and maintained long, stable telomeres. A constant expression level of p53 and a normal karyotype were preserved throughout long-term expansion, suggesting the safety of fetal MSCs. In conclusion, our results indicate that fetal MSCs could be an alternative, more accessible resource for cell therapy and regenerative medicine.

Gene expression profile of cytokines in patients with chronic graft-versus-host disease after allogeneic hematopoietic stem cell transplantation with reduced conditioning

There are no reliable markers useful to predict the onset or the evolution of chronic graft-versus-host disease (cGVHD) after allogeneic hematopoietic stem cell transplantation (HSCT), although several candidate biomarkers have been identified from limited hypothesis-driven studies. In this study we evaluated 14 patients who received a reduced intensity conditioning HSCT. Seven patients had cGVHD, whereas 7 never developed cGVHD during the period of observation. The expression of 114 cytokines in immunoselected cell populations was explored by microarray analysis and 11 cytokines were selected for further evaluation by real-time PCR. Differential gene expression measurements showed a significant up-regulation for INFγ (interferon, gamma) in CD8+ and for TNFSF3 (tumor necrosis factor superfamily, member 3) and for TNFSF10 (tumor necrosis factor superfamily, member 10) in CD14+ cell population when comparing cGVHD with control samples. The expression levels were significantly decreased for TNFSF10 in CD8+ cell population and for TNFSF12 (tumor necrosis factor superfamily, member 12) and for PDGFβ (platelet-derived growth factor, beta) in CD4+. Our data seem to suggest that different immune populations can play a role in cGVHD pathogenesis and the early detection of gene expression profile in these patients could be useful in the monitoring of GVHD. We hypothesized that PDGFβ down-regulation could represent a negative feedback to compensate for enhanced expression of its receptor recently reported.

Selection of CD271(+) cells and human AB serum allows a large expansion of mesenchymal stromal cells from human bone marrow

BACKGROUND

Mesenchymal stromal cells (MSC) are promising candidates for cell therapy and tissue engineering and may be used to treat acute graft-versus-host disease (GvHD). However, major obstacles for their clinical use are the required cell dose and the biosafety and potential immunogenicity of fetal bovine serum (FBS), which is a crucial supplement of all media currently used for the culture of MSC.

METHODS

In this study MSC were successfully expanded after selection of CD271 cells from human bone marrow (BM) mononuclear cells in medium supplemented with 10% pooled allogeneic human serum.

RESULTS

We isolated MSC from 10 healthy donor BM by plastic adherence and immunomagnetic selection of the CD271(+) fraction and expanded MSC in medium supplemented with pooled human allogeneic serum and animal serum. We isolated a homogeneous multipotent population by CD271(+) selection with a proliferation rate that was higher than MSC isolated by plastic adherence, 6.8+/-1.57 compared with 2.07+/-1.40 logs. Similar to cells generated in animal serum medium, MSC from allogeneic human serum were positive for mesenchymal markers and negative for hematopoietic markers; moreover they expressed embryonic stem cell genes. A normal karyotype and differentiation capacity into adipogenic, osteogenic and chondrogenic lineages and neurosphere-like structures were preserved throughout long-term culture.

DISCUSSION

Expansion of MSC is both feasible and large with a CD271-selected population in medium supplemented with 10% pooled allogeneic human serum, without loss of multipotent differentiation capacity or karyotype alterations.

Characterization and expansion of mesenchymal progenitor cells from first-trimester chorionic villi of human placenta

BACKGROUND

Mesenchymal stromal cells (MSC) have been identified in a variety of fetal and adult tissues, including bone marrow (BM), fetal blood and liver. We report on the isolation, expansion and differentiation in vitro of MSC-like cells from chorionic villi (CV).

METHODS

We evaluated 10 samples of CV collected at the first trimester (gestational age 11-13 weeks). We only used cells taken from back-up culture after a successful karyotype analysis. CV cells were characterized by morphologic, immunophenotypic and molecular analysis. The differentiation ability of mesenchymal and neural lineages was detected using specific culture conditions. Cell expansion was assessed after plating cells at different densities in different media, supplemented with animal and human serum.

RESULTS

CV cells showed a homogeneous population of spindle-shaped cells after the first passage. Cells expressed CD90, CD105, CD73, CD44, CD29 and CD13 but not CD45, CD14, CD34 and CD117. They expressed Oct-4, Rex-1, GATA-4 and nestin, which characterize the undifferentiated stem cell state. They differentiated into osteocytes, adipocytes, chondrocytes and neuronal cells. Cell expansion was greater than that of adult BM-derived MSC, 9 logs with fetal bovine serum and 6 logs with human serum. Despite their high proliferative capacity, we did not observe any karyotypic abnormalities after culture.

DISCUSSION

Our study shows that CV cells have better potential for expansion than adult stem cells. They can proliferate in a medium with human allogeneic serum and can differentiate into mesenchymal and neural lineages. CV cells may be an excellent cell source for therapeutic applications.

Hansenula polymorpha NMR2 and NMR4, two new loci involved in nitrogen metabolite repression

In the yeast Hansenula polymorpha (Pichia angusta) nitrate assimilation is tightly regulated and subject to a dual control: nitrogen metabolite repression (NMR), triggered by reduced nitrogen compounds, and induction, elicited by nitrate itself. In a previous paper [Serrani, F., Rossi, B. and Berardi, E (2001) Nitrogen metabolite repression in Hansenula polymorpha: the nmrl-l mutation. Curr. Genet. 40, 243-250], we identified five loci (NMR1-NMR5) involved in NMR, and characterised one of them (NMR1), which likely identifies a regulatory factor. Here, we describe two more mutants, namely nmr2-1 and nmr4-1. The first one possibly identifies a regulatory factor involved in nitrogen metabolite repression by various nitrogen sources alternative to ammonium. The second one, apparently involved in ammonium assimilation, probably has sensor functions.

The NII2 gene of Hansenula polymorpha is involved in nitrite assimilation

To establish a basis for genetic and molecular studies of nitrite assimilation in the methylotrophic yeast Hansenula polymorpha, we isolated and characterised six nitrite-negative mutants still capable of growing on nitrate. Gene isolation work yielded the NII2 gene, encoding a membrane protein homologous to the Saccharomyces cerevisiae Pho86p. Sequence analysis revealed an ORF of 860 bp encoding a 286-amino-acid protein with a predicted molecular mass of 32.8 kDa. This protein is shorter than its S. cerevisiae homologue, and is predicted to lack an ER-retention signal. Cell suspension work revealed that the null mutant is unable to take up nitrite from the medium.

Nitrogen metabolite repression in Hansenda polymorpha: the nmrl-l mutation

In Hansenula polymorpha, the expression of the nitrate assimilation metabolism is subjected to re-pression-derepression mechanisms triggered by reduced nitrogen compounds such as ammonium. To further our knowledge on the genetics of these regulatory mechanisms, a screening strategy for the isolation of mutants exhibiting nitrate reductase activities in the presence of reduced nitrogen compounds was set up. This strategy makes use of a nitrate+ methylamine mutant to isolate suppressors of its characteristic phenotype--the inability to grow on a nitrate plus methylamine medium. A total of 21 regulatory mutants were isolated with this strategy and grouped into five complementation classes. One of these mutants harbours the recessive mutation nmr1-1, which determines the derepression of the nitrate assimilation metabolism in media containing nitrate plus a repressing nitrogen source (ammonium, methylamine, glutamate, urea or aspartate). Therefore, nitrate reductase activities are detected in the presence of reduced nitrogen sources, as long as nitrate is also in the medium. Our data indicate that the processes of repression-derepression and induction are controlled by elements which are distinct. Furthermore, they indicate that Nmrlp is involved in repressing circuits which control not only the nitrate-utilisation pathway, but also other pathways which are necessary for the utilisation of nitrogen sources alternative to ammonium. Of considerable interest is the fact that our nmr1-1 mutant is derepressed in glutamate but not in glutamine. Since the phenotype of this mutant seems to exclude a glutamine synthetase defect, we suggest that glutamate (or a derivative of this compound) might be involved in signalling nitrogen metabolite repression in H. polymorpha. Thus, in H. polymorpha, a glutamine-dependent circuit may co-exist with a glutamine-independent circuit.