Hum. Reprod. Advance Access published online on January 31, 2008
Human Reproduction, doi:10.1093/humrep/dem417
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High frequency of fetal cells within a primitive stem cell population in maternal blood
a Levi
ar11 Department of Surgery, Imperial College London, Faculty of Medicine, Hammersmith Campus, Du Cane Road, London W12 0NN, UK 2 Department of Haematology, Imperial College London, Faculty of Medicine, Hammersmith Campus, Du Cane Road, London W12 0NN, UK 3 Department of Reproductive Biology, Imperial College London, Faculty of Medicine, Hammersmith Campus, Du Cane Road, London W12 0NN, UK
4 Correspondence address. Tel: +44-208-383-3430; E-mail: myrtle.gordon{at}imperial.ac.uk
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BACKGROUND: During pregnancy, fetal cells enter the maternal bloodstream resulting in fetal cell microchimerism. The fetal cells persist in the mother for decades and colonize a variety of maternal organs. They are associated with maternal autoimmune diseases and may also participate in tissue repair. The identity of the microchimeric cells is not certain but they must be able to persist long-term and have potential for multitissue differentiation.
METHODS AND RESULTS: Here we tested the hypothesis that the fetal microchimeric cells are primitive stem cells, represented by CD34+ adherent cells, which have a wide potential for differentiation. We isolated these stem cells from the blood of pregnant females (n = 25) and detected fetal cells of the correct gender, using fluorescence in situ hybridization, in a high proportion (71% male fetuses and 90% female fetuses; false positive rate 11%, false negative rate 29%) of cases. By RT–PCR, we demonstrated that the cells express Oct-4, Nanog and Rex-1. No fetal cells were detected in the mononuclear or total CD34+ cell populations but high frequencies (mean 11.8%) of fetal cells were detected in the adherent CD34+ cell population.
CONCLUSIONS: These results identify adherent CD34+ stem cells as candidate fetal microchimeric cells, which are capable of sustaining the fetal cell population in the long term and have the ability to colonize multiple tissues and organs.
Key words: microchimerism/fetal stem cells/CD34
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Introduction |
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Fetal cell microchimerism, first described in mice, refers to the presence of fetal cells in the maternal circulation and/or tissue without any discernible graft-versus-host reaction or graft rejection (Liegeous et al., 1977
). The full biological significance of this physiological phenomenon is not yet known, although it has been associated with disorders of pregnancy, autoimmune disease and the clinical outcome of allogeneic haematopoietic stem cell transplantation (Lapaire et al., 2007). Fetal cell microchimerism has been exploited for prenatal gender determination and potentially for prenatal diagnosis of karyotypic abnormalities. However, recent evidence suggests that microchimeric fetal cells may include stem cells capable of prolonging natural tissue repair and regeneration, and has stimulated debate about the cell type responsible for microchimerism (Bianchi, 2007; Rossi, 2004; Lapaire et al., 2007). Cells of fetal origin have been found within maternal haemopoietic and immune cell populations (Johnson et al., 2002; Khosrotehrani et al., 2004; Khosrotehrani and Bianchi, 2005), mesenchymal cells from the marrow (O’Donoghue et al., 2003) and tissues and organs such as heart, liver, spleen and thyroid (Johnson et al., 2002; Bayes-Genis et al., 2005; Khosrotehrani and Bianchi, 2005). In mouse models, recruitment of endogenous fetal cells participates in the response to tissue damage (Rossi, 2004; Lapaire et al., 2007). Furthermore, fetal cells can persist in the maternal circulation for a very long time (Bianchi et al., 1996; Adams et al., 2003; Guetta et al., 2003). Bianchi et al. (1996) showed that male CD34+CD38+ cells were detectable as long as 27 years post-partum. Microchimerism has been implicated as a factor in the longer lifespan of women (Johnson and Bianchi, 2004). Taken together, the evidence suggests that microchimeric fetal cells have stem cell properties, and they have been referred to as pregnancy-associated progenitor cells (PAPCs) (Khosrotehrani et al., 2004). Khosrotehrani and Bianchi (2005) have proposed a model wherein the PAPCs persist in a maternal stem cell niche but can home to damaged tissue as part of a tissue repair response.
The precise identity of the PAPCs has not been established, but it may be that of a haematopoietic, mesenchymal or placental stem cell, an endothelial cell or a haemangioblast (O’Donoghue et al., 2003; Mikkola et al., 2005; Bianchi, 2007). Recently, we identified a novel primitive stem cell population in human blood and bone marrow that may provide a candidate stem cell type (Gordon et al., 2006). These cells are a small quiescent subpopulation of the CD34+ cells and express genes corresponding to differentiation into several tissues suggesting that they may be able to regenerate damaged tissues. We hypothesize that fetal cells might be sequestered within this population of primitive, quiescent stem cells during and after pregnancy and may circulate in the bloodstream in order to exercise their tissue repair capacity. Here, we show that the frequency of fetal cells within this subpopulation of CD34+ cells is considerably higher than their frequency among the rest of the CD34+ cells or the whole mononuclear cell fraction.
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Patient selection and controls
Patients undergoing surgical termination of pregnancy during the first trimester up to and including week 9 were selected randomly. For all patients (n = 25), these were primary pregnancies. Control samples (n = 4) were provided by normal healthy male and female volunteers, and mothers of male children. Ethics committee approval and informed consent were obtained in all cases.
Collection and preparation of samples for analysis
Peripheral blood
Up to 20 ml, peripheral blood was collected by venesection from the study participants. In the case of the patients undergoing termination, the blood was taken before surgery commenced. The samples were layered on Lymphoprep (Axis-Shield, Kimbolton, UK) and centrifuged to obtain the mononuclear cell fraction. CD34+ cells were positively selected from the mononuclear cells using a CD34+ progenitor cell separation kit (Miltenyi Biotech, Surrey, UK) according to the manufacturer’s instructions. The purity of the isolated CD34+ cells was monitored by flow cytometry. To retrieve the adherent CD34+ cells, a circle of nail varnish was painted onto a glass microscope slide to form a well to retain CD34+ cells. The CD34+ cells were incubated on the slide at 37°C for 2 h. The slide was washed three times in phosphate-buffered saline to remove non-adherent cells and the adherent cells were fixed in acetone for 80 s at room temperature. For some experiments, slides of mononuclear cells and total CD34+ cells were prepared for analysis in the same way as explained above.
RNA isolation
RNA was isolated from fresh cells, and from cells that had been cultured for 7 days in 
-minimum essential medium (Gibco, UK) supplemented with 30% fetal bovine serum and cytokines [stem cell factor (SCF) 20 ng/ml, GM-SCF 1 ng/ml, interleukin-3 5 ng/ml, G-CSF 100 ng/ml] at 37°C in 5% CO2 in air, using the RNeasy Mini kit according to the manufacturer’s instructions (QIAGEN, UK). To ensure purity of the RNA, the samples were treated with DNase (Promega, UK). The RNA was then purified using the QIAGEN PCR Purification Kit, according to the manufacturer’s instructions. Total RNA concentration was determined by measuring the optical density (OD) at 260 nm in a spectrophotometer (Eppendorf, UK).
Reverse transcriptase–polymerase chain reaction
RT–PCR was carried out using the One-step RT-PCR Kit (Qiagen, UK). A master mix sufficient for 40 reactions was prepared in a 1.5 ml Eppendorf tube consisting of 300 µl 5 x RT–PCR buffer, 60 µl dNTP, 150 µl Q solution, 650 µl RNase free water and 80 µl RT-enzyme mix. 20 µl from the RT–PCR master mix was then aliquoted into each tube with an overlay of 50 µl of mineral oil to prevent evaporation. Positive controls were a pool of RNA known to be positive for the genes of interest (Oct-4, Nanog and Rex-1) by RT–PCR and sequence verification by the Medical Research Council sequencing laboratory at the Hammersmith Hospital. Both negative controls and culture medium controls were used to exclude false positive results. As an internal RNA standard, the housekeeping gene glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used. RT–PCR conditions used were as follows: reverse transcription at 50°C for 1 h; PCR activation at 95°C for 15 min; three-step cycling at 95°C for 1 min, N°C for 1 min, and 72°C for 1 min for 35 cycles; and final extension at 72°C for 10 min; where N is the gene-specific RT–PCR annealing temperature.
Primers used (all forward, then reverse) were as follows:
- Oct-4 (5'-CGAAAGAGAAAGCGAACCAG-3', 5'-AGGCACCTCAGTTTGAATGC-3')
- Nanog (5'-CAAATGTCTTCTGCTGAGATGC-3', 5'-GCAGAGATTCCTCTCCACAGTT-3');
- Rex-1 (5'-CGACAACCTTCTCGTCTACTGC-3', 5'-GTAGCGGAAGCGATACATCACC-3');
- GAPHD (5'-CGAGATCCCTCCAAAATCAA-3', 5'-ACCTGGTGCTCAGTGTAGCC-3').
Nested PCR
Nested PCR was performed by adding 2 µl of the corresponding RT–PCR product to each PCR tube along with 2 µl of the appropriate nested forward and backward primer mix and 20 µl of nested PCR mix. Nested PCR conditions used were as follows: 50°C for 1 min; 95°C for 15 min; 35 cycles of 95°C for 1 min, N°C for 1 min and 72°C for 1 min; and 72°C for 10 min; where N is the gene-specific nested PCR annealing temperature.
Primers used for nested PCR were as follows:
- Oct-4 (5'-AGAAGGATGTGGTCCGAGTG-3', 5'-GTGAAGTGAGGGCTCCCATA-3')
- Nanog (5'-GGATCTGCTTATTCAGGACAGC-3', 5-AGTAGAGGCTGGGGTAGGTAGG-3');
- Rex-1 (5'-GAGCAAGAAGTCCACCAAGAGG-3', 5'-CTGCTCATTCTTGAACTGGTGC-3');
- GAPHD (5'-GATCATCAGCAATGCCTCCT-3', 5'-AGGTCCACCACTGACACGTT-3').
Fetal tissue
A sample of fetal tissue was taken, with research ethics committee approval and informed consent, after surgical termination of pregnancy. After washing and digestion with collagenase (0.2 mg/ml for 2 h at 37°C), cells in the supernatant were deposited on a glass slide and fixed in methanol:acetic acid (3:1).
Immunofluorescence and fluorescence in situ hybridization
Immunofluorescent staining with fluorescein isothiocyanate (FITC) was used to confirm the identity of the adherent CD34+ cells on the slide by staining cell surface CD34 with FITC-conjugated anti-CD34 monoclonal antibody QBEND10 (Sutherland et al., 1992) kindly donated by Dr L. Healy. After staining for CD34, fluorescently labelled probes (Vysis, Maidenhead, UK) were used to identify X and Y chromosomes in the nuclei of the cells. The nuclei were located using 4',6-diamidino-2-phenylindole (DAPI) counterstain. Slides were observed under a fluorescence microscope and gender was analysed by scoring at least 200 cells per slide.
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In spite of the rarity of stem cells in steady-state blood, 20 ml samples yielded sufficient adherent CD34+ cells for analysis, irrespective of pregnancy status. The purity of isolated CD34+ cells was >99% (Fig. 1). Thus, 20 ml blood contained 4.6 ± 1.2 x 106 (mean ± SEM) CD34+ cells of which 5.0 ± 0.9 x 103 (0.1%) were adherent CD34+ cells. Fluorescence in situ hybridization (FISH) analysis of adherent CD34+ blood cells from male and female control individuals confirmed the reliability of the method in identifying cells of the correct gender (Fig. 2). Analyses were performed on blood samples from two women who had given birth to sons (one son aged 14 months in one case and two sons aged 15 months and 5 years in the other). In neither woman were any male cells detected among the 500 cells scored in the mononuclear or total CD34+ cell fractions; however, the frequencies of male cells within the adherent CD34+ cell subfraction were 0.4% and 0.5%, respectively. These results indicate that male fetal microchimeric cells can be specifically identified and are enriched in the primitive stem cell population in the blood. In addition, the adherent CD34+ stem cell population expressed the embryonic stem cell markers Oct-4, Rex-1 and Nanog (Fig. 3).
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Next, we examined cells from pregnant women (n = 25) who were undergoing elective surgical termination of pregnancy. In order to control for any false positive or false negative results, we obtained paired samples of maternal blood and fetal tissues (Table I). In 25 samples of fetal tissue examined by XY FISH, there were 7 males and 18 females. The reason for this female gender bias is not clear. Between 200 and 340 stem cells per sample were scored by immunofluorescent staining of CD34 and FISH. In five of the seven cases of women who aborted a male fetus, 11.8 ± 10.3% (mean±SD) of the stem cells were Y chromosome-positive. No Y chromosome-positive stem cells were found in the case of women who aborted a female fetus, providing further affirmation of the accuracy of male cell detection. Compared with the previous observation that male cells were only 0.4–0.5% of the adherent CD34+ cells in blood from mother of sons aged 14 months–5years, this result indicates that the frequency of circulating fetal stem cells may be higher during pregnancy than after delivery.
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False negative results were obtained from two of the cases carrying a male fetus (false negative rate = 28.6%) and, hence, false positive results for two of the female cases (false positive rate = 11.1%). The accuracy of detection of the male fetal cells was 71.4% and that of the females was 90%.
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Discussion |
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Many studies have demonstrated that fetal cells concentrate in clinically affected tissues, giving rise to the hypothesis that they may contribute to tissue repair and regeneration, but the identity of these PAPCs is not known (Bianchi, 2007
; Lapaire et al., 2007). We hypothesized that they are likely to be found within a primitive stem cell population, i.e. quiescent and therefore persistent in the mother, and able to differentiate into multiple tissue lineages. We further hypothesized that the primitive CD34+ adherent stem cell population we had isolated was a candidate repository for microchimeric cells. These adherent cells are a rare subpopulation comprising <1% of the total CD34+ cells in bone marrow and blood. They are capable of differentiation into tissue lineages and express appropriate phenotypic markers and genes for differentiation into liver, heart, pancreatic and vascular endothelial cells (Gordon et al., 2006). Significantly, the primitive CD34+ adherent stem cells are almost entirely quiescent (Gordon et al., 2006), which is consistent with an ability to persist in the mother’s body for many years (Bianchi et al., 1996). Consequently, these cells may have the potential to play a part in tissue repair later in life in microchimeric females (Srivatsa et al., 2001; Johnson and Bianchi, 2004; Khosrotehrani and Bianchi, 2005; Bayes-Genis et al., 2005; Guettier et al., 2005). These observations further highlight the likelihood that the fetal microchimeric cells probably have a primitive stem cell phenotype. Conversely, it has been hypothesized that primitive tissue stem cells may be remnants of fetal development (Ratajczak et al., 2007). In this regard, we found that adherent CD34+ cells expressed the embryonic stem cell markers, Oct-4, Rex-1 and Nanog.
Assays for fetal microchimeric cells are being actively pursued. In particular, cell-based assays are considered to be especially desirable because it then becomes possible to identify single cells of fetal origin and to perform prenatal diagnosis as well as gender assignment in the same cell (Bianchi and Hanson, 2006). Whereas many studies have demonstrated that fetal DNA can be detected in maternal blood using PCR (Bianchi, 2004), this approach does not have the same advantages as cell-based assays. Nucleated red blood cells in the maternal circulation are unique in having an exclusively fetal origin and have been used as a target cell population for fetal gender identification (Cha et al., 2005). Cells of fetal origin have been detected among other mature cell types in maternal blood, including lymphocytes, monocytes and natural killer cells (Loubiere et al., 2006), but these cell types are less likely than stem cells to persist in the long-term or to explain the observations of fetal cell microchimerism in diverse tissues. In contrast to published results using molecular techniques, we did not find any Y chromosome-positive cells in mononuclear fractions from the cases we examined. We acknowledge that the number of cases is small and it may be necessary to score more than 200 cells, or use more sensitive methodology such as PCR. However, our results demonstrate that the relative frequency of fetal microchimeric cells is higher in the more primitive stem cell population. Fetal cells have also been sought among cultured mesenchymal stem cells, but male cells were found in only 5% of women tested (O’Donoghue et al., 2003). Adams et al. (2003) found male DNA in CD34+ cell-enriched fractions from a proportion of leukapheresed blood samples. More recently, FISH analysis had been used for interphase cytogenetics of CD34+ cells. Thus, several studies have detected Y chromosome-positive cells in 
40% of blood samples from male pregnancies (Little et al., 1997; Jansen et al., 2000; Guetta et al., 2003).
CD34+ cells are a heterogeneous population consisting of stem cells and progenitor cells for different lineages of peripheral blood cells. However, CD34+ cells include the adherent subfraction which has a much broader differentiation potential than the remainder of the CD34+ cells (Gordon et al., 2006). Their candidature as an origin for PAPCs and, conversely, their identity as a primitive population, are now strengthened by the present observation that they contain an enriched population of microchimeric fetal cells. Indeed, it has been proposed that some ‘adult’ stem cell populations may, in fact, be fetal in origin and represent a novel stem cell population with therapeutic potential (Bianchi, 2007). In addition, our results suggest that the stem cell population with regenerative capacity is a mix of adult and fetal microchimeric cells.
Feto-maternal haemorrhage after first trimester termination of pregnancy results in an 80-fold increase in frequency of fetal cell numbers in maternal blood (Bianchi et al., 2001; O’Donoghue et al., 2003), and it is important to note that the blood samples we analysed were taken before surgical intervention. Reported frequencies of fetal cells in maternal blood range from 1 in 5000 to 1 in 10 000 000 (Price et al., 1991; Hamada et al., 1993; Bianchi et al., 1997; O’Donoghue et al., 2003). Consequently, the frequencies of microchimeric cells we observed, amounting to 17% of the subfractionated CD34+ cells, represent a considerable enrichment of fetal microchimeric cells. This may have been influenced by pre-operative stress at the time the blood was taken since we observed much lower frequencies 1–5 years post-partum. Also, histocompatibility between mother and fetus (Lambert et al., 2000; Nelson, 2001) and time elapsed since delivery influence the degree of fetal cell microchimerism. Nonetheless, the fetal cells were found in the adherent subpopulation of CD34+ cells in all evaluable cases.
Analyses were correct in terms of gender assignment in 92% of the cases studied and the sensitivity of detection of at least one XY cell by FISH was 71.4% for women aborting a male fetus. Although we acknowledge that our number of cases is rather small, this result compares favourably with the results of the National Institute of Child Health and Human Development Fetal Cell Isolation Study (NIFTY) study of 1292 informative cases where the sensitivity of detection was 41% (Bianchi et al., 2002). Further work is needed to evaluate the additional possibility that our method may advance the ability to identify gender prenatally and also raises the possibility of interphase cytogenetic diagnosis of congenital abnormalities before birth.
Fetal cell microchimerism has potential implications for every female who has been pregnant and may have beneficial effects on lifespan and tissue repair (Khosrotehrani and Bianchi, 2005; Lapaire et al., 2007). Our study contributes to the development of simple technology for fetal cell enrichment in maternal blood samples (Bianchi and Hanson, 2006) that may facilitate further studies of these issues as well as contributing to the debates concerning the cell type involved in feto-maternal microchimerism (Khosrotehrani et al., 2004; Rossi, 2004; Bianchi, 2007; Lapaire et al., 2007) and the developmental origin of stem cells earmarked for use in regenerative medicine (Ratajczak et al., 2007).
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The work was funded by RevealCyte Ltd.
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Adams KM, Lambert NC, Heimfeld S, Tylee TS, Pang JM, Erickson TD, Nelson JL. Male DNA in female donor apheresis and CD34-enriched productes. Blood (2003) 102:3845–3847.
Bayes-Genis A, Bellosillo B, de la Calle O, Salido M, Roura S, Ristol FS, Soler C, Martinez M, Espinet B, Serrano S, et al. Identification of male cardiomyocytes of extracardiac origin in the hearts of women with male progeny: male fetal cell microchimerism of the heart. J Heart Lung Transplant (2005) 12:179–183.
Bianchi DW. Circulating fetal DNA: its origin and diagnostic potential. Placenta (2004) 18(Suppl A):S93–S101.
Bianchi DW. Fetomaternal cell trafficking: a story that begins with prenatal diagnosis and may end with stem cell therapy. J Pediatr Surg (2007) 42:12–18.[CrossRef][Web of Science][Medline]
Bianchi DW, Hanson J. Sharpening the tools: a summary of a National Institutes of health workshop on new technologies for detection of fetal cells in maternal blood for early prenatal diagnosis. J Matern Fetal Neonatal Med (2006) 19:199–207.[CrossRef][Web of Science][Medline]
Bianchi DW, Zickwolf GK, Weil GJ, Sylvester S. Male fetal progenitor cells persist in maternal blood for as long as 27 years postpartum. Proc Natl Acad Sci USA (1996) 93:705–708.
Bianchi DW, Williams JM, Sullivan LM, Hanson FW, Klinger KW, Shuber AP. PCR quantitation of fetal cells in maternal blood in normal and aneuploid pregnancies. Am J Hum Genet (1997) 61:822–829.[Web of Science][Medline]
Bianchi DW, Farina A, Weber W, Delli-Bovi LC, Deriso M, Williams JM, Klinger KW. Significant fetal–maternal haemorrhage after termination of pregnancy: implications for development of fetal cell microchimerism. Am J Obst Gynecol (2001) 184:703–706.[CrossRef][Web of Science][Medline]
Bianchi DW, Simpson JL, Jackson LG, Elias S, Holzgreve W, Evans MI, Dukes KA, Sullivan LM, Klinger KW, Bischoff FZ, et al. Fetal gender and aneuploidy detection using fetal cells in maternal blood: analysis of NIFTY data. Prenat Diagn (2002) 22:609–615.[CrossRef][Web of Science][Medline]
Cha DH, Khosrotehrani K, Bianchi DW, Johnson KL. The utility of an erythroblast scoring system and gender-independent short tandem repeat (STR) analysis for the detection of aneuploid fetal cells in maternal blood. Prenat Diagn (2005) 25:586–591.[CrossRef][Web of Science][Medline]
Gordon MY, Levicar N, Pai M, Bachellier P, Dimarakis I, Al-Allaf F, M’Hamdi H, Thalji T, Welsh JP, Marley SB, et al. Characterization and clinical application of human CD34+ stem/progenitor cell populations mobilized into the blood by granulocyte colony-stimulating factor. Stem Cells (2006) 24:1822–1830.[CrossRef][Web of Science][Medline]
Guetta E, Gordon D, Simchen MJ, Goldman B, Barkai G. Hematopoietic progenitor cells as targets for non-invasive prenatal diagnosis: detection of fetal CD34+ cells and assessment of post-delivery persistence in the maternal circulation. Blood Cells Mol Dis (2003) 30:13–21.[CrossRef][Web of Science][Medline]
Guettier C, Sebagh M, Buard J, Feneux D, Ortin-Serrano M, Gigou M, Tricottet V, Reynes M, Samuel D, Feray C. Male cell microchimerism in normal and diseased female livers from fetal life to adulthood. Hepatology (2005) 42:35–43.[CrossRef][Web of Science][Medline]
Hamada H, Arinami T, Kubo T, Hamaguchi H, Iwasaki H. Fetal nucleated cells in maternal peripheral blood: frequency and relationship to gestational age. Hum Genet (1993) 91:427–432.[CrossRef][Web of Science][Medline]
Jansen MW, Korver-Hakkennes K, van Leenen D, Brendenberg H, Wildschut HI, Waldimiroff JW, Ploemacher RE. How useful is the in vitro expansion of fetal CD34+ progenitor cells from maternal blood samples for diagnostic purposes? Prenat Diagn (2000) 20:725–731.[CrossRef][Web of Science][Medline]
Johnson KL, Bianchi DW. Fetal cells in maternal tissue following pregnancy: what are the consequences? Hum Reprod Update (2004) 10:497–502.
Johnson KL, Samura O, Nelson JL, McDonell WM, Bianchi DW. Significant fetal cell microchimerism in a nontransfused woman with hepatitis C: evidence of long-term survival and expansion. Hepatology (2002) 36:1295–1297.[CrossRef][Web of Science][Medline]
Khosrotehrani K, Bianchi DW. Multilineage potential of fetal cells in maternal tissue: a legacy in reverse. J Cell Sci (2005) 118:1559–1563.
Khosrotehrani K, Johnson KL, Cha DH, Salomon RN, Bianchi DW. Transfer of fetal cells with multilineage potential to maternal tissue. JAMA (2004) 292:75–80.
Lambert NC, Evans PC, Hashizumi TL, Maloney S, Gooley T, Furst DE, Nelson JL. Cutting edge: persistent fetal microchimerism in T lymphocytes is associated with HLA-DQA1*0501: implications in autoimmunity. J Immunol (2000) 164:5545–5549.
Lapaire O, Hosli I, Zanetti-Daellenbach R, Huang D, Jaeggi C, Gatfield-Mergenthaler S, Hahn S, Holzgreve W. Impact of fetal–maternal chimerism on women’s health—a review. J Matern Fetal Neonatal Med (2007) 20:1–5.[CrossRef][Web of Science][Medline]
Liegeous A, Escourrou J, Ouvre E, Charriere J. Microchimerism: a stable state of low ratio proliferation of allogeneic bone marrow. Transplant Proc (1977) 9:273–276.[Web of Science][Medline]
Little MT, Langlois S, Wilson RD, Lansdorp PM. Frequency of fetal cells in sorted subpopulations of nucleated erythroid and CD34+ hematopoietic progenitor cells from maternal peripheral blood. Blood (1997) 89:2347–2358.
Loubiere LS, Lambert NC, Flinn LJ, Erickson TD, Yan Z, Guthrie KA, Vickers KT, Nelson JL. Maternal microchimerism in healthy adults in lymphocytes, monocyte/macrophages and NK cells. Lab Invest (2006) 86:1185–1192.[Web of Science][Medline]
Mikkola HK, Gekas C, Orkin SH, Dieterlen-Lievre F. Placenta as a site for hematopoietic stem cell development. Exp Hematol (2005) 33:1048–1054.[CrossRef][Web of Science][Medline]
Nelson JL. HLA relationships of pregnancy, microchimerism and autoimmune disease. J Reprod Immunol (2001) 52:77–84.[CrossRef][Web of Science][Medline]
O’Donoghue K, Choolani M, Chan J, de la Fuente J, Kumar S, Campagnoli C, Bennett PR, Roberts IA, Fisk NM. Identification of fetal mesenchymal stem cells in maternal blood: implications for non-invasive prenatal diagnosis. Mol Human Reprod (2003) 9:497–502.
Price JO, Elias S, Wachtel SS, Klinger K, Dockter M, Tharapel A, Shulman LP, Phillips OP, Meyers CM, Shook D. Prenatal fetal diagnosis with fetal cells isolated from maternal blood by multiparameter flow cytometry. Am J Obstet Gyn (1991) 165:1731–1737.[Web of Science][Medline]
Ratajczak MZ, Machalinski B, Wojakaowski W, Ratajczak J, Kucia M. A hypothesis for an embryonic origin of Oct (4+) stem cells in bone marrow and other tissues. Leukemia (2007) 21:860–867.[Web of Science][Medline]
Rossi G. Nature of stem cell involved in fetomaternal microchimerism. Lancet (2004) 364:1936.[Web of Science][Medline]
Srivatsa B, Srivatsa S, Johnson KL, Samura O, Lee SL, Bianchi DW. Microchimerism of presumed fetal origin in thyroid specimens from women: a case–control study. Lancet (2001) 358:2034–2038.[CrossRef][Web of Science][Medline]
Sutherland DR, Marsh JC, Davidson J, Baker MA, Keating A, Mellors A. Differential sensitivity of CD34 epitopes to cleavage by Pasteurella haemolytica glycoprotease: implications for purification of CD34-positive progenitor cells. Exp Hematol (1992) 20:590–599.[Web of Science][Medline]
Submitted on July 18, 2007; resubmitted on October 31, 2007; accepted on November 14, 2007.
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