Fibroblastoid Colony-forming Units Research Articles

Brain-death donors as an alternative source of human stromal mesenchymal cells for cell-based therapy

Background & Aim In the last decades, human mesenchymal stromal cells (hMSC) have been widely investigated, due to their capacity to extensively proliferate in vitro while maintaining their differentiation potential into several mesodermal lineages. Besides, they have low immunogenicity, immunomodulatory effects, ability to migrate and graft at inflammation sites and secrete bioactive molecules. These properties are of great interest for applications in cell therapy and regenerative medicine and hMSCs are currently being evaluated in several clinical trials. Various sources of hMSCs have been studied, being bone marrow (BM) the most commonly used for autologous or allogeneic clinical applications. In the latter case, one of the difficulties is the scarce availability of living donors of BM. In contrast, the alternative use of deceased donors as an allogeneic source has been little explored. The aim of our study was to evaluate the relative potential of BM from brain-death donors (BDD) as a source of hMSCs for cell therapy, obtained from two different sites: femur (F) and iliac crest (IC). Methods, Results & Conclusion Adequate procedures were developed for BM collection and processing, as well as for in vitro culture, immunophenotyping and differentiation. Fourteen donor-matched BM samples (IC and F) were processed from seven deceased donors (Table 1). Our results show that it is possible to obtain viable hMSC from both sites. Although the total number of mononuclear cells (MNC) per gram of BM appears to be greater in the CI than in F, no statistically significant differences were observed between both sources. Neither the total content of fibroblastoid colony-forming units (CFU-F) per gram of BM nor the amount of CFU-F per MNC differ significantly. The comparative analysis of MSC yields showed that there were no significant differences in MSC obtained per gram of IC-BM or F-BM during the first three passages of cell culture. Furthermore, there were no statistical differences in cell doubling time and population duplications. Cultured cells from both sites exhibited the ability to adhere to plastic and express CD105, CD73, CD90 but not CD45, CD34, CD14 markers by flow cytometry analysis. Trilineage differentiation was also achieve, meeting the ISCT minimum criteria to define hMSC. These results show the feasibility to obtain hMSC from two sites in BDD, and underscores the potential of this new source as a suitable allogeneic source of hMSC for cell-based therapies.

Behavior and biocompatibility of rabbit bone marrow mesenchymal stem cells with bacterial cellulose membrane.

BackgroundTissue engineering has been shown to exhibit great potential for the creation of biomaterials capable of developing into functional tissues. Cellular expansion and integration depends on the quality and surface-determinant factors of the scaffold, which are required for successful biological implants. The objective of this research was to characterize and evaluate the in vitro characteristics of rabbit bone marrow mesenchymal stem cells (BM-MSCs) associated with a bacterial cellulose membrane (BCM). We assessed the adhesion, expansion, and integration of the biomaterial as well as its ability to induce macrophage activation. Finally, we evaluated the cytotoxicity and toxicity of the BCM.MethodsSamples of rabbit bone marrow were collected. Mesenchymal stem cells were isolated from medullary aspirates to establish fibroblast colony-forming unit assay. Osteogenic, chondrogenic, and adipogenic differentiation was performed. Integration with the BCM was assessed by scanning electron microscopy at 1, 7, and 14 days. Cytotoxicity was assessed via the production of nitric oxide, and BCM toxicity was assessed with the MTT assay; phagocytic activity was also determined.ResultsThe fibroblastoid colony-forming unit (CFU-F) assay showed cells with a fibroblastoid morphology organized into colonies, and distributed across the culture area surface. In the growth curve, two distinct phases, lag and log phase, were observed at 15 days. Multipotentiality of the cells was evident after induction of osteogenic, chondrogenic, and adipogenic lineages. Regarding the BM-MSCs’ bioelectrical integration with the BCM, BM-MSCs were anchored in the BCM in the first 24 h. On day 7 of culture, the cytoplasm was scattered, and on day 14, the cells were fully integrated with the biomaterial. We also observed significant macrophage activation; analysis of the MTT assay and the concentration of nitric oxide revealed no cytotoxicity of the biomaterial.ConclusionThe BCM allowed the expansion and biointegration of bone marrow progenitor cells with a stable cytotoxic profile, thus presenting itself as a biomaterial with potential for tissue engineering.

Heparin concentration is critical for cell culture with human platelet lysate

Background aimsCulture media for mesenchymal stromal cells (MSCs) are generally supplemented with fetal bovine serum. Human platelet lysate (hPL) has been proven to be a very effective alternative without the risk of xenogeneic infections or immune reactions. In contrast to fetal bovine serum, hPL comprises plasma, and anticoagulants—usually unfractionated heparin (UFH)—need to be added to prevent gel formation. MethodsCultures of MSCs in hPL media with various concentrations of UFH and enoxaparin, a low-molecular-weight heparin (LMWH), were systematically compared with regard to proliferation, fibroblastoid colony-forming unit frequency, immunophenotype and in vitro differentiation. ResultsAt least 0.61 IU/mL UFH or 0.024 mg/mL LMWH was necessary for reliable prevention of coagulation of hPL pools used in this study. Higher concentrations impaired cellular proliferation in a dose-dependent manner even without benzyl alcohol, which is commonly added to heparins as a bacteriostatic agent. Colony-forming unit frequency was also reduced at higher heparin concentrations, particularly with LMWH, whereas no significant effect was observed on cellular morphology or immunophenotype. High concentrations of heparins reduced the in vitro differentiation toward adipogenic and osteogenic lineages. ConclusionsHeparin concentration is critical for culture of MSCs in hPL media; this is of particular relevance for cellular therapy where cell culture procedures need to be optimized and standardized.

Stromal cells from the adipose tissue-derived stromal vascular fraction and culture expanded adipose tissue-derived stromal/stem cells: a joint statement of the International Federation for Adipose Therapeutics and Science (IFATS) and the International Society for Cellular Therapy (ISCT)

Background aimsAdipose tissue is a rich and very convenient source of cells for regenerative medicine therapeutic approaches. However, a characterization of the population of adipose-derived stromal and stem cells (ASCs) with the greatest therapeutic potential remains unclear. Under the authority of International Federation of Adipose Therapeutics and International Society for Cellular Therapy, this paper sets out to establish minimal definitions of stromal cells both as uncultured stromal vascular fraction (SVF) and as an adherent stromal/stem cells population. MethodsPhenotypic and functional criteria for the identification of adipose-derived cells were drawn from the literature. ResultsIn the SVF, cells are identified phenotypically by the following markers: CD45-CD235a-CD31-CD34+. Added value may be provided by both a viability marker and the following surface antigens: CD13, CD73, CD90 and CD105. The fibroblastoid colony-forming unit assay permits the evaluation of progenitor frequency in the SVF population. In culture, ASCs retain markers in common with other mesenchymal stromal/stem cells (MSCs), including CD90, CD73, CD105, and CD44 and remain negative for CD45 and CD31. They can be distinguished from bone-marrow-derived MSCs by their positivity for CD36 and negativity for CD106. The CFU-F assay is recommended to calculate population doublings capacity of ASCs. The adipocytic, chondroblastic and osteoblastic differentiation assays serve to complete the cell identification and potency assessment in conjunction with a quantitative evaluation of the differentiation either biochemically or by reverse transcription polymerase chain reaction. ConclusionsThe goal of this paper is to provide initial guidance for the scientific community working with adipose-derived cells and to facilitate development of international standards based on reproducible parameters.

Donor Age of Human Platelet Lysate Affects Proliferation and Differentiation of Mesenchymal Stem Cells

The regenerative potential declines upon aging. This might be due to cell-intrinsic changes in stem and progenitor cells or to influences by the microenvironment. Mesenchymal stem cells (MSC) raise high hopes in regenerative medicine. They are usually culture expanded in media with fetal calf serum (FCS) or other serum supplements such as human platelet lysate (HPL). In this study, we have analyzed the impact of HPL-donor age on culture expansion. 31 single donor derived HPLs (25 to 57 years old) were simultaneously compared for culture of MSC. Proliferation of MSC did not reveal a clear association with platelet counts of HPL donors or growth factors concentrations (PDGF-AB, TGF-β1, bFGF, or IGF-1), but it was significantly higher with HPLs from younger donors (<35 years) as compared to older donors (>45 years). Furthermore, HPLs from older donors increased activity of senescence-associated beta-galactosidase (SA-βgal). HPL-donor age did not affect the fibroblastoid colony-forming unit (CFU-f) frequency, immunophenotype or induction of adipogenic differentiation, whereas osteogenic differentiation was significantly lower with HPLs from older donors. Concentrations of various growth factors (PDGF-AB, TGF-β1, bFGF, IGF-1) or hormones (estradiol, parathormone, leptin, 1,25 vitamin D3) were not associated with HPL-donor age or MSC growth. Taken together, our data support the notion that aging is associated with systemic feedback mechanisms acting on stem and progenitor cells, and this is also relevant for serum supplements in cell culture: HPLs derived from younger donors facilitate enhanced expansion and more pronounced osteogenic differentiation.

Population dynamics of mesenchymal stromal cells during culture expansion

Mesenchymal stromal cells (MSC) are heterogeneous and only a subset possesses multipotent differentiation potential. It has been proven that long-term culture has functional implications for MSC. However, little is known how the composition of subpopulation changes during culture expansion. We addressed the heterogeneity of MSC using limiting-dilution assays at subsequent passages. In addition, we used a cellular automaton model to simulate population dynamics under the assumption of mixed numbers of remaining cell divisions until replicative senescence. The composition of cells with adipogenic or osteogenic differentiation potential during expansion was also determined at subsequent passages. Not every cell was capable of colony formation upon passaging. Notably, the number of fibroblastoid colony-forming units (CFU-f) decreased continuously, with a rapid decay within early passages. Therefore the CFU-f frequency might be used as an indicator of the population doublings remaining before entering the senescent state. Predictions of the cellular automaton model suited the experimental data best if most cells were already close to their replicative limit by the time of culture initiation. Analysis of differentiated clones revealed that subsets with very high levels of adipogenic or osteogenic differentiation capacity were only observed at early passages. These data support the notion of heterogeneity in MSC, and also with regard to replicative senescence. The composition of subpopulations changes during culture expansion and clonogenic subsets, especially those with the highest differentiation capacity, decrease already at early passages.

Replicative senescence of mesenchymal stem cells causes DNA-methylation changes which correlate with repressive histone marks

Cells in culture undergo replicative senescence. In this study, we analyzed functional, genetic and epigenetic sequels of long-term culture in human mesenchymal stem cells (MSC). Already within early passages the fibroblastoid colony-forming unit (CFU-f) frequency and the differentiation potential of MSC declined significantly. Relevant chromosomal aberrations were not detected by karyotyping and SNP-microarrays. Subsequently, we have compared DNA-methylation profiles with the Infinium HumanMethylation27 Bead Array and the profiles differed markedly in MSC derived from adipose tissue and bone marrow. Notably, all MSC revealed highly consistent senescence-associated modifications at specific CpG sites. These DNA-methylation changes correlated with histone marks of previously published data sets, such as trimethylation of H3K9, H3K27 and EZH2 targets. Taken together, culture expansion of MSC has profound functional implications - these are hardly reflected by genomic instability but they are associated with highly reproducible DNA-methylation changes which correlate with repressive histone marks. Therefore replicative senescence seems to be epigenetically controlled.

Impact of individual platelet lysates on isolation and growth of human mesenchymal stromal cells

Culture medium for mesenchymal stromal cells (MSC) is frequently supplemented with fetal calf serum (FCS). FCS can induce xenogeneic immune reactions, transmit bovine pathogens and has a high lot-to-lot variability that hampers reproducibility of results. Several studies have demonstrated that pooled human platelet lysate (HPL) provides an attractive alternative for FCS. However, little is known about the variation between different platelet lysates. We compared activities of individual HPL on initial fibroblastoid colony-forming units (CFU-F), proliferation, in vitro differentiation and long-term culture. These data were correlated with chemokine profiles of HPL. Isolation of MSC with either HPL or FCS resulted in similar CFU-F frequency, colony morphology, immunophenotype and adipogenic differentiation potential. Osteogenic differentiation was even more pronounced in HPL than FCS. There were significant differences in MSC proliferation with different HPL, but it was always higher in comparison with FCS. Cell growth correlated with the concentration of platelet-derived growth factor (PDGF) and there was a moderate association with platelet counts. All HPL facilitated expansion for more than 20 population doublings. Taken together, reliable long-term expansion was possible with all HPL, although there was some variation in platelet lysates of individual units. Therefore the use of donor recipient-matched or autologous HPL is feasible for therapeutic MSC products.

Adipose tissue-derived stem cells for cell therapy of airway allergic diseases in mouse

The purpose of this study was to compare murine mesenchymal stem cells (MSCs) isolated from bone marrow (BM) and adipose tissue (AT) for the selection of suitable MSCs in cell therapy of an airway allergic animal model. We compared MSCs of BALB/c mice derived from BM and AT with respect to proliferation potential, immunophenotype, and multilineage differentiation capacity. In proliferation potential, MSCs from AT (ASCs) showed higher fibroblastoid colony-forming units frequencies and colony-forming efficiency than MSCs from BM (BMSCs). The flow cytometry analysis showed that both ASCs and BMSCs expressed MSCs-related antigens (CD90 and CD105), whereas they did not express hematopoiesis-related antigens (CD45 and CD11b). There was no significant difference in adipogenic, osteogenic, and chondrogenic differentiation between the murine ASCs and BMSCs. In conclusion, the present study has shown that ASCs had higher CFU-F frequencies and colony-forming efficiency than BMSCs. ASCs and BMSCs presented a similar surface immunophenotype and multilineage differentiation capacity. Therefore, ASCs in BALB/c mice might be a more useful material for cell therapy of the airway allergic experiment due to the abundance, relatively easy harvesting and high proliferation potential.

Effects of high-dose chemotherapy on bone marrow multipotent mesenchymal stromal cells isolated from lymphoma patients

High-dose chemotherapy (HDCT) followed by autologous stem cell transplantation is a widely applied treatment for hematological and autoimmune diseases. Little is known about the effects of this therapy on multipotent mesenchymal stromal cells (MSCs). We aimed to characterize, morphologically and functionally, MSCs isolated from bone marrow aspirates of patients after HDCT. We studied 12 consecutive lymphoma patients submitted to BEAM conditioning regimen followed by autologous stem cell transplantation 28 to 1836 days before the sample collection. Thirteen normal donors were used as control. MSCs were isolated by adherence to plastic and expanded ex vivo by culture in flasks containing alpha-minimum essential medium plus 15% fetal bovine serum. The cell population isolated showed a typical MSC morphology, immunophenotype, and differentiation capacity into adipogenic, osteogenic, and chondrogenic lineages. The MSCs obtained from patients with Hodgkin's disease and non-Hodgkin's lymphoma showed decreased fibroblastoid colony-forming unit count (p = 0.023) and increased doubling time (p = 0.031) related to the control group. The total cell expansion of MSCs from normal subjects was marginally superior to the patient group (p = 0.064). There were no differences in gene expression profile, MSCs plasticity, or hematopoiesis support capability between control and patient group. Results suggest that HDCT applied to lymphoma patients damaged MSCs, which was demonstrated by their reduced clonogenic potential, doubling time, and cell expansion rates when compared to controls.

Effects of imatinib mesylate in osteoblastogenesis

Imatinib mesylate (IM), a tyrosine kinase inhibitor currently used in chronic myeloid leukemia (CML), may also affect the growth of other cellular systems besides CML cells. Because it has been reported that IM may affect bone tissue remodeling, we evaluated the effects of IM on osteoblastic differentiation of human bone marrow mesenchymal stem cells (hBM-MSCs). After 21 days of culture, hBM-MSCs treated with IM (1 microM) alone or osteogenic medium (OM) + IM showed changes in morphology with evidence of extracellular mineralization and increased mRNA expression of osteogenic markers, such as RUNX2, osteocalcin (OCN), and bone morphogenetic protein (BMP-2). We also observed that levels of OCN and the osteoprotegerin (OPG)/receptor activator of nuclear factor-kappa B ligand (RANKL) ratio (OPG/RANKL ratio) were increased in the surnatant of the 21-day culture with IM or OM + IM compared to controls (p<0.005). In addition, we found that in 46 serum samples collected from CML patients treated with IM for 3 to 24 months, the OPG/RANKL ratio increased after 3 and 6 months (p<0.004) returning back to the basal level after 24 months of IM treatment. In these patients, OCN levels were low at diagnosis but they increased throughout the IM treatment, approaching normal levels at 24 months of IM therapy. In summary, our data show that IM increases mRNA expression of osteogenic markers in hBM-MSCs and increases the OPG/RANKL ratio and the OCN levels both in surnatant of hBM-MSCs cultured with IM and in serum of patients treated with IM, thus indicating that IM potentially favors osteoblastogenesis.

Possibilities of physical-chemical regulation of stem cells' pool

Modulating influence of electric impulses, visible light, some microelements is studied in parameters which are near to physio-logic ones on life activity of progenitor and mature cells of blood system in vitro and in situ. Content of granulocyte and fibroblastoid colony-forming units, concentration of colony-stimulating and colony-inhibiting activities, their concentration were determined , myelograms and morphologic signs of myelocariocytes apoptosis and necrosis were scored, saturation by chrom ions of peripheral blood erythrocytes was studied in mice bone marrow. The results showed that cell effects of physical-chemical influ-ences are small specific. Nevertheless, one may perform both positive and negative regulating influence on life activity of stromal precursors in dependence of energy density and stimulus concentration . The effect is due not only by direct but mediated reactions regulating direction and intensity of metabolic intracellular processes. It is suggested that one of target cells capable of change in-crease program of hemopoietic and stromal cells-progenitors of bone marrow in dependence of physical stimulus strength are lym-phocytes.

Protection against γ-Irradiation with 5-Androstenediol

We showed previously that treatment of gamma-irradiated female B6D2F1 mice with 5-androstenediol (AED) enhanced survival, stimulated myelopoiesis, and ameliorated radiation-induced decreases in circulating neutrophils and platelets. We have now tested survival in male CD2F1 mice, and we have investigated molecular and functional effects on neutrophils and bone marrow stromal cells and screened for toxicity in female B6D2F1 mice. AED (160 mg/kg, subcutaneously, 24 hours before irradiation) enhanced survival in male CD2F1 mice with a dose-reduction factor of 1.23, similar to the dose-reduction factor of 1.26 found previously for female B6D2F1 mice. Expression of CD11b, a developmental marker, was reduced on circulating neutrophils after either in vivo AED administration or whole-body γ-irradiation (3 Gy), but neutrophil peroxidase activity was unchanged. Stromal cell progenitors (fibroblastoid colony-forming units) were reduced in marrow 5 days after AED injection in nonirradiated mice. Clinical chemistry, histopathology, and behavioral assays showed no evidence of toxicity. We conclude that AED and related steroids are attractive candidates to explore as countermeasures to high- and low-level ionizing radiation.

Tumour induction by methyl-nitroso-urea following preconceptional paternal contamination with plutonium-239.

We have investigated the possibility that transgenerational effects from preconceptional paternal irradiation (PPI) may render offspring more vulnerable to secondary exposure to an unrelated carcinogen. 239Pu (0, 128 or 256 Bq g(-1)) was administered by intravenous injection to male mice, 12 weeks before mating with normal females. Two strains of mouse were used -- CBA/H and BDF1. Haemopoietic spleen colony-forming units (CFU-S) and fibroblastoid colony-forming units (CFU-F), a component of their regulatory microenvironment, were assayed independently in individual offspring at 6, 12 and 19 weeks of age. Bone marrow and spleen from each of these mice were grown in suspension culture for 2 or 7 days for assessment of chromosomal aberrations. Female BDF1 were injected with methyl-nitroso-urea (MNU) as a secondary carcinogen at 10 weeks of age and monitored for onset of leukaemia/lymphoma. Mean values of CFU-S and CFU-F were unaffected by preconceptional paternal plutonium-239 (PP-239Pu), although for CFU-F in particular there was an apparent increase in variation between individual animals. There was significant evidence of an increase in chromosomal aberrations with dose in bone marrow but not in spleen. By 250 days, 68% of MNU-treated control animals (no PPI) had developed thymic lymphoma (62%) or leukaemia (38%). The first case arose 89 days after MNU administration. In the groups with PPI, leukaemia/lymphoma developed from 28 days earlier, rising to 90% by 250 days. Leukaemia (65%) now predominated over lymphoma (35%). This second generation excess of leukaemia appears to be the result of PPI and may be related to inherited changes that affect the development of haemopoietic stem cells.

Induction of lympho-haemopoietic malignancy: impact of preconception paternal irradiation

Purpose: To investigate the effects of preconception paternal irradiation (PPI) from injected 239Pu on the susceptibility to induction of lympho-haemopoietic malignancy by subsequent irradiation or exposure to a chemical carcinogen. Materials and Methods: The male CBA/H and DBA2 mouse was injected with 0, 128 or 256Bqg -1 239Pu 12 weeks before mating with the normal CBA/H and C57Bl female respectively. CBA/H offspring were exposed to 3.3Gy gamma -rays total body irradiation: BDF offspring were injected with 50mgkg -1methyl nitrosourea (MN1 U). The offspring were assayed for changes in bone marrow progenitor cell numbers and chromosome aberrations and were followed up for subsequent induction of neoplasia. Results: While the untreated mouse showed a normal distribution for cellularity, spleen colony-forming units (CFU-S) and fibroblastoid colony-forming units (CFU-F), significant numbers of PPI offspring presented levels outside the normal range. There was a tendency for them also to show increased, dose-related, levels of chromosomal aberrations. Offspring treated with irradiation or MNU developed an increased incidence of lymphohaemopoietic malignancies. Conclusions: These studies have shown that PPI results in offspring that are more susceptible to the induction of lymphohaemopoietic malignancy on encountering a secondary carcinogenic insult. This may be linked to inherited chromosomal instability and abnormal kinetics of haemopoiesis. The experiments indicate a potential mechanism by which an increased incidence of leukaemia may be linked to PPI.

Gamma-Ray-Induced Cell Killing and Chromosome Abnormalities in the Bone Marrow of p53-Deficient Mice

Resistance to the lethal effects of ionizing radiation has been demonstrated in a wide variety of cell types with defects in the p53 gene (thymocytes, splenic B and T cells, in vitro hemopoietic colony-forming cells and intestinal cells of the mouse, embryo cells of the rat, and human Burkitt's lymphoma cells). In contrast, Slichenmeyer et al. (Cancer Res. 53, 4164-4167, 1993) found no evidence of resistance in fibroblasts derived from p53 null mice. The aim of our study was to compare the radiation response of hemopoietic colony-forming cells (in vitro CFC) and of fibroblastoid colony-forming cells or units (CFU-F) within the same tissue (marrow) in p53 null mice (-/-), heterozygotes (+/-) and wild-type animals (+/+). We have also tested the hypothesis that, in proliferating cells, radiation-induced cell killing is mediated through chromosome damage by examining the relationship between these end points in hemopoietic cells of the three mouse types. Both in vitro CFC and CFU-F of -/- mice were resistant to cell killing compared with +/+ and +/- mice whose cellular sensitivities were indistinguishable. The resistance was characterized by a broader "shoulder" on the cell survival curve, i.e. a higher extrapolation number but similar D0 values using the multitarget model or a lower alpha coefficient using the linear-quadratic model. The frequency of chromosomally abnormal marrow cells after irradiation was similar for the three genotypes. However, marrow cells with aberrations carried more aberrations in -/- mice than in +/+ or +/- mice such that the total number of aberrations per 100 cells was higher in -/- mice. Since there were no differences in the yields of aberrations between genotypes in spleen lymphocytes or in CFU-F (both noncycling at the time of irradiation) and less mitotic inhibition in -/- marrow cells than in +/+ or +/- cells, the chromosomal radiosensitivity of -/- marrow hemopoietic cells might be related to reduced cell cycle delay allowing insufficient time for repair, but other explanations have been considered. We postulate that the radiation resistance of both hemopoietic CFC and CFU-F in -/- mice is a consequence of the failure of DNA/chromosome damage to trigger apoptosis or permanent cell cycle arrest to the same extent as in the +/+ or +/- mice: hence the lack of correlation between chromosome damage and cell death in the three mouse types.

Radiation‐induced DNA damage in canine hemopoietic cells and stromal cells as measured by the comet assay

Stromal cell progenitors (fibroblastoid colony-forming unit; CFU-Fs) are representative of the progenitor cell population of the hemopoietic microenvironment in bone marrow (BM). Previous studies of the radiation dose—effect relationships for colony formation have shown that canine CFU-Fs are relatively radioresistant as characterized by a D0 value of about 2.4 Gy. In contrast, hemopoietic progenitors are particularly radiosensitive (D0 values = 0.12-0.60 Gy). In the present study, the alkaline single-cell gel electrophoresis technique for the in situ quantitation of DNA strand breaks and alkalilabile sites was employed. Canine buffy coat cells from BM aspirates and cells harvested from CFU-F colonies or from mixed populations of adherent BM stromal cell (SC) layers were exposed to increasing doses of X-rays, embedded in agarose gel on slides, lysed with detergents, and placed in an electric field. DNA migrating from single cells in the gel was made visible as “comets” by ethidium bromide staining. Immediate DNA damage was much less in cultured stromal cells than in hemopoietic cells in BM aspirates. These results suggest that the observed differences in clonogenic survival could be partly due to differences in the type of the initial DNA damage between stromal cells and hemopoietic cells. © 1996 Wiley-Liss, Inc.

Effect of Benzene on Fibroblastoid Colony-Forming Units in Mice

After exposure of C57BL6 x DBA/2 mice to benzene in air their number of bone marrow fibroblastoid precursor cells, CFU-F, was determined. The CFU-F exhibited an increasing plating efficiency, giving rise to a larger number of colonies and to colonies of greater size. This effect was dose dependent. When the mice were exposed for 16 weeks and were then allowed to rest, their CFU-F plating efficiency returned to normal within 6 weeks, but then increased again. Hematopoietic stem cells, such as CFU-S and CFU-C exhibited a dose-dependent depression. The in vitro exposure of bone marrow cells to benzene metabolites resulted in a dose-dependent depression of CFU-F numbers.

Reduction of granulocyte-macrophage progenitor cells (CFU-C) and fibroblastoid colony-forming units (CFU-F) by leukemic cells in human and murine leukemia.

The number of bone marrow granulocyte-macrophage progenitor cells (CFU-C) and fibroblastoid colony-forming units (CFU-F) was significantly smaller in acute leukemia patients. To analyze the mechanism by which CFU-C and CFU-F were reduced, the study on murine myeloid leukemia was carried out. In murine leukemia, bone marrow CFU-C and CFU-F decreased in number in correlation with the proliferation of leukemic cells. Murine leukemic cells suppressed the growth of CFU-C and CFU-F in the mixed culture of leukemic cells and normal murine marrow cells. Furthermore, leukemic cell-conditioned medium inhibited the growth of CFU-F. The results show that murine leukemic cells themselves and/or humoral factors produced by them give inhibitory effects on the growth of not only CFU-C but also CFU-F.

Relationship between fibroblastoid colony-forming units (CFU-f) and hemopoietic precursor cells in normal human bone marrow.

To clarify the relationship between fibroblastoid colony-forming units (CFU-f) and hemopoietic precursor cells, simultaneous assays of CFU-f, CFU-e, BFU-e, and CFU-c from the bone marrow of 10 healthy volunteers were performed. The number of CFU-f correlated positively with CFU-e (r = 0.905, P less than 0.001) and BFU-e (r = 0.842, P less than 0.005), but not with CFU-c (r = 0.530, P greater than 0.1). These findings support the hypothesis that CFU-f is related to erythropoiesis in the steady state of hemopoietic tissue. Further studies of the relationship between CFU-f and erythroid precursor cells in patients with hematological diseases may help clarify their pathophysiology.