Fetal and maternal progenitor cells in co-culture respond equally to erythropoietin

To explore potentially selective growth conditions for fetal cells in cultures from the blood of pregnant women, we investigated if fetal and adult erythroid progenitors with different hemoglobin expression programs are differentially responsive to erythropoietin (EPO). Co-cultures of clonogenic cells from 12-week fetal and adult peripheral blood were established, and the development of erythropoietic cells was monitored using flow cytometric profiles of correlated cellular contents of fetal and adult hemoglobin (HbF and HbA, respectively). Adult nucleated red cells were classified as F+A-, F+A+ or F-A+. All fetal cells were F+A-. The population of F+A- cells was flow-sorted and fetal cells were identified by fluorescence in situ hybridization (FISH) using chromosome-specific probes. Delayed EPO addition revealed that all types of erythroid cells entered the EPO-dependent phase with similar kinetics, beginning at about Day 4. The data suggest that fetal and adult erythroid stem/progenitor cells have the same initial maturation kinetics in culture independent of their hemoglobin chain expression program. Fetal and adult cells with different hemoglobin profiles also showed similar EPO dose-response curves, determined for different intervals during the first 2 weeks of culture. Thus, the kinetics of entry into the phase of EPO dependence, as well as the sensitivity to EPO at various stages of development, are essentially the same for erythropoietic progenitor cells derived from adult and early fetal blood, which rules out the possibility of using the timing or concentration of EPO for the selective growth of fetal cells from the blood of pregnant women.

Fetal cells from maternal blood: purpose, biological questions, technical challenges

The maternal peripheral blood circulation can serve as a source of fetal cells for the prenatal diagnosis of genetic abnormalities, eliminating the need for fetal cell sampling by invasive techniques. However, the extreme scarcity of these cells leads to a variety of biological questions and technical hurdles on the way to a clinical test. On the biological side, we need to know the numbers of fetal cells, their distinguishing properties, and the variables that affect these properties. On the technical side, we need to identify fetal cells and maximize both yield and purity of the isolation procedure. Here we review the questions and challenges as they present themselves in our specific approach to the fetal cell isolation project. We also briefly discuss the question of whether these cells could help to diagnose fetal infections.

Differential effects of interleukin-3 on fetal and adult erythroid cells in culture: implications for the isolation of fetal cells from maternal blood

Fetal clonogenic erythroid cells may be present in maternal blood and serve as a source of fetal DNA for prenatal genetic diagnosis. Proliferating nucleated red cells in cultures from first and second trimester fetal blood contain only fetal haemoglobin (HbF; F+A- cells), whereas nucleated red cells from adult blood contain also adult haemoglobin (HbA; F+A+ or F-A+ cells). Thus, fetal red cells can be identified and flow sorted. However, a few adult cells are also F+A-, which reduces the purity of fetal cell isolation. Culture media optimized for erythropoiesis contain interleukin-3 (IL3). We show here that IL3 strongly stimulates the growth of F+ cells (both F+A- and F+A+) in cultures from adult blood but has only a comparatively small effect on F+A- cells in cultures from fetal blood. This difference is maintained in the unified conditions of co-cultures of adult and fetal cells, so that the purity of fetal cell sorts can be increased by omitting IL3 from the culture medium. We further show that IL3 accelerates the exhaustion of the long-term division potential of adult cells, allowing fetal secondary colonies to be identified by their size following a two-stage culture scheme. Thus, the choice to omit or include IL3 in the growth medium of maternal blood cultures should depend on whether fetal nucleated red cells are to be isolated by flow sorting after one week, or by picking secondary colonies after a later secondary culture stage.

Selectively increased growth of fetal hemoglobin-expressing adult erythroid progenitors after brief treatment of early progenitors with transforming growth factor beta

We have studied the effect of transforming growth factor beta (TGFbeta) on erythropoiesis in cultures from adult peripheral blood, using flow cytometric enumeration of fetal hemoglobin (HbF)-containing cells. TGFbeta caused a dramatic increase in the proportions of cells that accumulated HbF together with adult hemoglobin (HbA) (F+A+ cells). This highly significant (P <.0001) increase in F+ cell proportion was achieved by TGFbeta treatment during the first 4 days of culture and was sustained during further culture expansion in the absence of TGFbeta. The increase in F+ cell proportions did not depend on the cytokine combination (EPO+SCF+IL3, EPO+SCF, EPO+IL3, SCF+IL3) used during the phase of TGFbeta treatment. Increased F+ cell proportions were paralleled by an increased molecular ratio of HbF/ HbF+ HbA, measured by cation exchange high-performance liquid chromatography (HPLC). In addition to the effect on F+ cell proportions, TGFbeta caused a dramatic increase in overall cell division potential. By the time cultures reached terminal growth arrest (12-14 days in controls and 18-26 days after TGFbeta), the overall numbers of F+ cells produced per initially seeded clonogenic cell was approximately 10 times higher in the TGFbeta-treated cultures than in the controls. We propose to investigate whether the TGFbeta-induced increase in relative and absolute numbers of nucleated F+ cells, as demonstrated in vitro, can be translated into increased F+ erythrocytes in vivo, allowing therapeutic application for some beta-hemoglobinopathies. (Blood. 2000;95:2967-2974)

Identification of fetal nucleated red cells in co-cultures from fetal and adult peripheral blood: differential effects of serum on fetal and adult erythropoiesis

Seeking to optimize a novel method of isolating rare fetal erythroid cells in cultures from maternal blood, we have explored the effects of serum supplement on fetal and adult erythropoiesis. We used flow cytometry and sorting after labelling with antibodies to fetal haemoglobin (HbF) and adult haemoglobin (HbA). In adult blood-derived cultures, most nucleated red cells accumulated either only adult haemoglobin (F-A+) or a combination of fetal and adult haemoglobin (F+A+). Only a few were F+A-. Serum affected the proportions of adult cells expressing fetal haemoglobin (both F+A- and F+A+), which were minimized, but not eliminated altogether, with the use of charcoal-treated sera at low concentrations. In contrast, the expansion of fetal red cells, which made only fetal haemoglobin (F+A-) during at least one week of culture, was strongly increased with the use of charcoal treated sera, due to the removal of a charcoal-absorbable inhibitor. In co-cultures of fetal and adult erythroid cells, fetal cells could be enriched in the order of 200-fold by flow sorting with the F+A- criterion. However, since adult F+A- cells could not be suppressed completely, the purity of sorted fetal cells still depended on the relative numbers of fetal and maternal erythroid clonogenic cells in the blood sample. Thus, we demonstrate a method by which fetal nucleated red cells potentially present in maternal blood cultures can be identified and isolated from the vast majority of maternal erythroid cells, based on their correlated contents of fetal and adult haemoglobin.

Differential development of fetal and adult haemoglobin profiles in colony culture: isolation of fetal nucleated red cells by two-colour fluorescence labelling

Fetal cells in maternal peripheral blood are a source of fetal DNA for prenatal genetic diagnosis, but their numbers are so small and variable that a reliable isolation procedure has yet to be demonstrated. The problem of scarcity may be overcome by amplification of fetal progenitor cells in cultures from maternal blood samples. One challenge is to identify post-culture fetal cells and colonies. We have found that the progeny of fetal and adult erythroid progenitors developed differential haemoglobin profiles in co-culture. Fetus-derived cells initially made only fetal haemoglobin (HbF) and began to express adult haemoglobin (HbA) only after intracellular HbF had reached maximum levels, which occurred after c 7 d in culture. By this time the large majority of adult-derived erythroid cells contained already high levels of HbA alone or combined with HbE Using the HbF+ HbA- criterion, we were able to flow-sort fetal cells with up to nearly 50% purity from some post-termination blood cultures, and with >90% purity in cultures from maternal blood spiked with 1% blood from the fetus. Fetal cell purity depended on culture time and serum supplement. After 7-10 d, purity was higher in low concentrations of human cord serum (1-3%) than in the standard 30% fetal calf serum. This was reversed at later times. Thus, if fetal clonogenic erythroid cells were present in maternal blood. their progeny could be isolated from most adult erythoid cells based on haemoglobin profiles. Cultures using CD34+ cells could be performed complementary to other methods targeting more mature fetal cells in the same maternal blood samples, thus increasing the overall chances of finding fetal cells and potentially providing clonal isolation of such cells.

Continuous quality improvement decreases length of stay and adverse events: a case study in an interventional cardiology program

A study was performed to assess the effectiveness of continuous quality improvement in achieving a better quality of care for patients undergoing coronary interventions. Increasing utilization of new coronary interventional devices has incurred a higher incidence of complications, prolonged hospital stay, and related costs. Using a clinical information system, we adopted continuous quality improvement to control the incidence of complications and postprocedural length of stay. Multiple regression analysis and a matched case-control study were performed to detect complications related to postprocedural length of stay and their causes among 342 patients. The results led to the modification of the postprocedural heparin anticoagulation protocol, which was followed by the introduction of a ticlopidine-based poststent anticoagulation regimen. Two sequential groups of patients (n = 261, n = 266) were selected to compare postprocedural length of stay and frequency of complications with those for the first group. Adjustments were made for patients and procedural characteristics through stratification and multiple regression methods. Blood transfusion was the most important predictor of prolonged hospital stay (partial R2 = 0.26, P < 0.01). A high level of postprocedural anticoagulation and intracoronary stent use were significantly associated with blood transfusion (P = 0.01, P = 0.02, respectively). The comparison among the three groups showed that heparin protocol change reduced only postprocedural length of stay (P < 0.001) for patients without stents, whereas the stent change in anticoagulation protocol significantly reduced both transfusion and hospital stay for patients with stents (P < 0.001, P < 0.05, respectively). Continuous quality improvement based on clinical information is promising to control both complications and hospital costs. Physician involvement is necessary throughout the process.

A mutation in the epidermal growth factor receptor in waved-2 mice has a profound effect on receptor biochemistry that results in impaired lactation

The mutant mouse waved-2 (wa-2) is strikingly similar to transforming growth factor alpha-deficient mice generated by gene targeting in embryonic stem cells. We confirm that wa-2 is a point mutation (T-->G resulting in a valine-->glycine substitution at residue 743) in the gene encoding the epidermal growth factor (EGF) receptor. wa-2 fibroblastic cells lack high-affinity binding sites for EGF, and the rate of internalization of EGF is retarded. Although the tyrosine kinase activity of wa-2 EGF receptors is significantly impaired, NIH 3T3 cells lacking endogenous EGF receptors but overexpressing recombinant wa-2 EGF receptor cDNA are mitogenically responsive to EGF. While young and adult wa-2 mice are healthy and fertile, 35% of wa-2 mice born of homozygous wa-2 mothers die of malnutrition because of impaired maternal lactation.