Helene Stroh

Cervical cancer and microchimerism

OBJECTIVE To determine whether microchimerism is involved in the pathogenesis or progression of cervical cancer. METHODS Cervical tissue was obtained from eight women who had at least one live-born son and who underwent radical hysterectomy after a diagnosis of cervical cancer. Control tissue was obtained from four women without cervical cancer who had at least one live-born son and from three women with cervical cancer and no male births. Tissue sections were analyzed with fluorescence in situ hybridization for the presence of fetal cells, defined by an X and Y chromosome. Immunolabeling was used to determine the phenotype of the presumed fetal cells. RESULTS Male cells were found in cervical tissue from all four patients for whom large sections (approximately 1.5 x 2 cm) were analyzed. Only one male cell was found in two of the four patients for whom small biopsy specimens (approximately 0.1 x 0.5 cm) were analyzed. No male cells were found in tissue specimens from controls, whether they were small or large sections. In immunolabeling studies, eight of 18 male cells from one patient were CD45-positive and nine of 37 male cells from two patients were cytokeratin-positive. No cells were positive for both markers. CONCLUSION Cervical cancer might be associated with microchimerism, possibly from fetomaternal cell trafficking. These results further expand the potential relationship between microchimerism and disease in women.

Fetal Cell Isolation from Maternal Blood Cultures by Flow Cytometric Hemoglobin Profiles

Objective: We conducted a trial to test if the blood of pregnant women contains fetal clonogenic erythroid cells the progeny of which can be identified and isolated by a newly developed flow-sorting procedure. Methods: We have previously demonstrated the identification of fetal nucleated red cells in cocultures of fetal and adult blood. The procedure is based on profiles of the correlated contents of fetal and adult hemoglobin (HbF and HbA, respectively), using antibodies specific for the different hemoglobin chains. In such profiles, fetal cells contain only HbF, while the vast majority of adult cells contain either only HbA or a combination of HbA and HbF. HbF+ HbA– cells are flow sorted and fetal cells identified by fluorescence in situ hybridization, using chromosome-specific probes. This technique provides a yield that approaches 100%, meaning that fetal cells will be found even if the culture contains only a single fetal erythroid colony among thousands of maternal colonies. Peripheral blood samples were obtained from 11 women carrying chromosomally normal male fetuses, from 5 women carrying trisomy 21 fetuses, and from 2 women carrying trisomy 18 fetuses. A further six samples came from women with an unknown fetal karyotype. As positive controls, we used blood samples drawn after termination procedures that tended to induce some fetomaternal hemorrhage. In parallel to the method being tested, we employed alternative techniques of fetal cell detection: one third of the mononuclear cell preparations from each maternal blood sample was not cultured but labeled with anti-HbF antibodies for flow sorting of F+ cells. Ten percent of the total harvested cell population of each culture was subjected to quantitative polymerase chain reaction analysis targeting a Y-chromosome-specific sequence. Results: Most posttermination blood samples yielded fetal cells with high purity which demonstrates the validity of the method. However, no fetal cells were found in any of the maternal blood samples with normal or abnormal pregnancies, neither before nor after culture. Conclusion: We conclude that a cell culture approach targeting clonogenic erythroid cells offers no advantage over established methods of direct isolation.

Increased fetal cell trafficking in murine lung following complete pregnancy loss from exposure to lipopolysaccharide

To determine whether chemically induced miscarriage affects fetomaternal trafficking in a mouse model, we measured the amount of fetal DNA present in various maternal organs by polymerase chain reaction amplification following exposure to lipopolysaccharide (LPS). As the frequency of fetal cells and the number of animals with detectable microchimerism following LPS injection were significantly increased, particularly in lung tissue compared to controls, with no signs of an inflammatory response, we conclude that LPS-induced miscarriage results in increased murine fetomaternal cell trafficking, supporting a relationship between fetal loss and the establishment of fetal cell microchimerism.

Maternal background strain influences fetal–maternal trafficking more than maternal immune competence in mice

The objective of this study was to determine if fetal-maternal cell trafficking is affected by maternal immune competence and/or parental background strain using fluorescence-activated cell sorting (FACS). In our experience the sensitivity of FACS allows for the detection of 5 fetal in 10(7) maternal cells and assessment of cell surface phenotype. Wild-type C57BL/6J (n=18), FVB/NJ (n=15), and immunodeficient B6129S7-Rag1(tm1Mom)/J (n=16) female mice were mated to C57BL/6J males homozygous for the green fluorescent protein (GFP) transgene. Single cell suspensions of maternal lung, liver, spleen, bone marrow, and blood were analyzed between late gestation (day e16-18) and 1 day post-partum for the number of GFP-positive fetal cells in relation to 10(7) maternal cells and the percentage of GFP-positive cells that expressed the surface markers CD11b, CD29, CD34, CD44, or CD105. The highest relative proportions of GFP-positive fetal cells were observed in maternal lungs and livers from immunocompetent allogenic females. Among congenic matings, fetal cell microchimerism was higher in immunodeficient compared with immunocompetent females. Maternal strain and strain differences between the mother and father statistically significantly affected both the numbers of fetal cells and the relative distribution of cell types in maternal organs. The highest relative proportion of fetal cells was observed in allogenic matings with immunocompetent females. Since allogenic matings are more similar to those that occur in humans, future studies using animal models of microchimerism should consider incorporating this type of experimental design.

Fetal Cells in the Murine Maternal Lung Have Well-Defined Characteristics and Are Preferentially Located in Alveolar Septum

The transfer of fetal cells to maternal organs occurs in mouse and human pregnancy. Techniques such as polymerase chain reaction and flow cytometry do not permit study of fetal cell morphology or anatomic location. Using a green fluorescent protein (GFP) transgenic mouse model, our objective was to determine whether GFP+ signal emanates from intact or degraded fetal cells, and whether they have a characteristic appearance and location within maternal lung. Four wild-type female mice were mated to males homozygous for the Gfp transgene and studied at days e16-18. Controls were 2 females mated to wild-type males. Morphologic appearance and anatomic position of each GFP+ object within maternal lung was recorded. GFP signals were sufficiently bright to be visualized without anti-GFP antibody and were confirmed by confocal microscopy to be separate from fluorescent artifact. Of 438 GFP+ objects detected, 375 (85.6%) were from intact cells, and 63 (14.4%) were acellular. Four distinct categories of intact cells were observed. Of these, 23.2% had mononuclear morphology with a relatively large nucleus and GFP+ cytoplasm (Group A). An additional group of cells (10.1%) had mononuclear morphology and podocyte extensions (Group B). The remainder of cells had fragmented nuclei or cytoplasm. Both intact cells and acellular fragments were predominantly localized to the maternal alveolar septum (P<0.0001). This study demonstrates that fetal GFP+ cells are predominantly located in the alveolar septum and have characteristic morphologies, although it remains unclear whether these represent distinct categories of cells or degrading cells. Nevertheless, this naturally acquired population of fetal cells in maternal lung should be considered in studies of lung biology and repair.