Clonal culture of fetal cells from maternal blood

Transplacental traffic after in utero mesenchymal stem cell transplantation

Transplacental traffic of fetal progenitor and differentiated cells is a well-known phenomenon in pregnancies. We hypothesize that intrauterine stem cell transplantation leads to microchimerism in the dams and that this is gestational age-dependent. EGFP+ fetal liver-derived mesenchymal stem cell (MSC) (10(5) per fetus) were injected intraperitoneally into congeneic and allogeneic recipient fetuses at E12 versus E13.5 of murine pregnancy (56 dams). Engraftment in maternal organs was evaluated using TaqMan quantitative polymerase chain reaction (PCR) and fluorescence microscopy during pregnancy (1, 3, and 7 days after in utero transplantation [IUT]) and after delivery (1 and 4 weeks after delivery). One day after IUT donor cells were mainly found in the placenta (E12: 9/10 dams vs. E13.5: 4/8 dams) and laparotomy site (E12: 5/10 dams vs. E13.5: 4/8 dams). Three days after IUT these probabilities decreased significantly in the placenta to 3/8 and 1/3, respectively, whereas it was increased within the surgical wound to 8/8 and 2/4. One week after IUT donor cells could be detected in other single maternal organs, such as bone marrow or spleen. The surgical wound was chimeric in all dams. One week after delivery the surgical wound was still a major site of engraftment in both groups. E12 IUT resulted in detectable donor cell microchimerism in the maternal bone marrow (3/4), liver (2/4), lungs (1/4), spleen (1/4), and thymus (1/4), whereas engraftment probabilities were lower following E13.5 IUT (BM: 1/4, liver: 2/4, lungs: 1/4, spleen: 1/4, thymus: 0/4). At 4 weeks after delivery persistent microchimerism was found only after E12 IUT in various maternal organs (BM: 1/4, spleen: 1/4, lungs: 1/4) and within newly created surgical wounds (3/4), but completely not in the E13.5 group. Allogeneic IUT did also not result in any detectable long-term fetal microchimerism. An earlier IUT might lead to a higher transplacental traffic of donor MSC and persistent microchimerism within maternal tissues. Even 4 weeks after delivery, these cells are present in surgical wounds.

Differential effects of culture conditions on the migration pattern of stromal cell-derived factor-stimulated hematopoietic stem cells

Evidence is mounting that hematopoietic stem cells (HSCs) play a critical role in bone marrow regeneration and tissue renewal, for which migration is an obvious prerequisite. Computer-aided analysis and a three-dimensional collagen matrix assay enabled us to analyze single-cell migratory characteristics of stromal cell-derived factor-1 alpha (SDF-1 alpha)-stimulated cord blood-derived HSCs. We defined and resolved specific migratory parameters in spontaneous and SDF-1 alpha-induced migration of these cells. The addition of interleukin 6 to the culture medium led to differential SDF-1 alpha-stimulated migratory response, which comprised a recruitment of nonmoving cells and an increase in speed and frequency of pauses but a decrease in pause duration. We were thus able to decipher the exact parameters that result in an increase in the migration of HSCs and demonstrate that extensive analysis of single-cell behavior is elementary in the study of stem cell migration.

Fetomaternal cell traffic, pregnancy-associated progenitor cells, and autoimmune disease

Fetal cells in maternal blood are a potential source of fetal genetic material that can be obtained non-invasively. Efforts to isolate these cells from maternal peripheral blood are limited by their low circulating numbers (approximately 1 per ml of maternal blood in euploid pregnancies). Expansion of these cells by culture would provide more cells for diagnosis and give an opportunity to study fetal metaphase chromosomes. Despite extensive optimization of culture conditions, many groups have failed reproducibly to grow fetal cells from pre-procedural maternal samples. An unexpected benefit of this research has been the discovery of a novel population of fetal cells, the pregnancy-associated progenitor cell (PAPC), which remains in maternal blood and tissue for decades following delivery. These cells might play a role in some autoimmune diseases, such as scleroderma. PAPCs appear to have stem cell characteristics, such as the ability to proliferate and differentiate. Recently developed animal models will help to ascertain whether these cells cause disease, respond to disease, or have therapeutic applications.

Fetal nucleated red blood cells in peripheral blood of pregnant women: detection and determination of location on a slide using laser-scanning cytometry

OBJECTIVE

The purpose of the study was to assess the feasibility of analysis of fetal nucleated red blood cells (NRBC) present in the maternal circulation by laser-scanning cytometry.

METHODS

CD71-positive cells were obtained by magnetic cell sorting of peripheral blood of pregnant women after density centrifugation. Immunofluorescence for the Hbgamma-chain was combined with fluorescent staining of DNA (TO-PRO-3) and fluorescence in situ hybridization (FISH) with a Y-chromosome specific probe. The cells were scanned on a slide using a laser-scanning cytometer (LSC). Events double positive for Hbgamma and TO-PRO-3 were relocated and their morphology and FISH reactivity were visually assessed. Determination of male fetal sex with LSC was compared with findings from amniocentesis.

RESULTS

In 8/15 pregnancies with male fetuses and in 0/9 with females (apart from one case with a male/female twin pregnancy), we detected Y-chromosome-positive NRBC. In pregnancies with female fetuses, Y-chromosome-positive cells other than NRBC were found in all women who had previously given birth to male babies, whereas women with no abortion and no male babies in their history did not present with Y-chromosome-positive non-NRBC.

CONCLUSION

On the basis of automatic relocation of once-defined cells of fetal origin from the current pregnancy, laser-scanning cytometry is likely to facilitate repeated (poly-)FISH analysis and single-cell PCR for noninvasive prenatal diagnosis.

Non-invasive prenatal diagnosis: on the horizon?

The launch of the genomics and postgenomics era has greatly expanded our understanding of the genetic basis of many diseases. In conjunction with the sociocultural trend to delay childbirth and to maintain smaller family units, extra demand may be placed on the existing prenatal diagnostic services. The inherent risk of fetal loss associated with current prenatal diagnostic procedures, such as amniocentesis and chorionic villus sampling, has spurred research into non-invasive prenatal diagnosis. Much research has been conducted on the exploitation of fetal genetic material present in the maternal circulation. The initial focus was on the isolation of intact fetal cells and subsequently, the existence of extracellular fetal DNA in maternal plasma was realized. Exciting developments have been achieved in recent years. A large-scale trial to evaluate the clinical utility of fetal cell isolation from maternal blood for fetal aneuploidy diagnosis was launched and data were recently published. Much has taken place in the research of fetal DNA analysis in maternal plasma and in one example, namely prenatal RhD determination, this type of analysis has been used in the clinical setting. This paper reviews the technological developments in non-invasive prenatal diagnosis.

Developments in laboratory techniques for prenatal diagnosis

Ongoing trends in prenatal diagnosis aim at early, rapid, and ideally noninvasive diagnosis as well as at the improvement of risk-screening for aneuploidy. Interphase-fluorescence in situ hybridization and quantitative fluorescence polymerase chain reaction are efficient tools for the rapid exclusion of selected aneuploidies in addition to the established direct preparation of chromosomes from chorionic villi. Interphase fluorescence in situ hybridization has also made possible the diagnosis of selected chromosome abnormalities in single cells (e.g. in preimplantation genetic diagnosis) or noninvasive diagnosis. More complex multicolor fluorescence in situ hybridization approaches are currently being evaluated. Single cell polymerase chain reaction is the key technique for the molecular diagnosis of a growing number of monogenic conditions before implantation or, still more experimental, in fetal cells retrieved from the maternal circulation. New sources for noninvasive diagnosis came into play such as fetal DNA or cell nuclei in maternal plasma. The combination of biochemical parameters in the maternal serum, namely free beta-human chorionic gonadotropin with pregnancy associated plasma protein A and sonographic markers, has already dramatically increased the sensitivity of risk screening in the first trimester of pregnancy.

Inability to clonally expand fetal progenitors from maternal blood

OBJECTIVES

To confirm the recent report of the culture of single clones of fetal progenitor cells from maternal blood.

METHODS

Hemopoietic progenitor cells were cultured from 16 blood samples obtained from women pregnant with a male singleton fetus. Single colonies were isolated by micro-manipulation and examined by multiplex real-time PCR.

RESULTS

Of a total of 1,674 colonies examined, 1,648 were identified as being maternal. No colonies were detected of fetal origin.

CONCLUSIONS

The clonal expansion of single fetal colonies from the maternal circulation is not feasible by current methods.