A regional-based newborn hearing screening program: the Emilia-Romagna model after ten years of legislation.

Background: Hearing loss, occurring in 1-3/1,000 newborns in the well-babies population, is one of the most common congenital diseases, and hearing screening at birth still represents the only means for its early detection. Since 2011 the Emilia Romagna Regional Health Agency has recommended Newborn Hearing Screening for all babies at its birth points and for newborns moving to the region. The aims of this study are to analyze the results of this regional-based Newborn Hearing Screening program and to discuss the impact of the legislative endorsement on the organization. Material and methods: This is an observational retrospective chart study. The recordings of well-babies and babies at Neonatal Intensive Care Units were collected during the period from January 1st 2015 to December 31st 2020. The following data were included: Newborn Hearing Screening coverage, percentage of refer at otoacoustic emissions, prevalence and entity of hearing loss, unilateral/bilateral rate, presence of audiological risk factors. Results: More than 99% of a total of 198,396 newborns underwent the Newborn Hearing Screening test during the period January 1st 2015 to December 31st 2020, with a coverage ranging between 99.6% and 99.9%. Overall, the percentage of confirmed hearing loss cases was about 17-30 % of refer cases, 745 children received a diagnosis of hearing loss (prevalence 3.7/1,000). Considering profound hearing loss cases, these represent 13% of bilateral hearing loss. Conclusion: A regional-based Newborn Hearing Screening program is valuable and cost-effective. In our experience, the centralization of the data system and of the data control is crucial in order to implement its efficiency and effectiveness. Healthcare policies, tracking systems and public awareness are decisive for a successful programme implementation.

Feasibility, preliminary efficacy, and accessibility of a twitter-based social support group vs Fitbit only to decrease sedentary behavior in women.

BACKGROUND: Health behavior change interventions delivered by social media allow for real-time, dynamic interaction, peer social support, and experimenter-provided content. AIMS: We tested the feasibility, acceptability, and preliminary efficacy of a novel Twitter-based walking break intervention with daily behavior change strategies and prompts for social support, combined with a Fitbit, vs. Fitbit alone. METHODS: In a 2-group pilot, 45 sedentary women from a heart clinic were randomized to Twitter + Fitbit activity tracker (Tweet4Wellness, n = 23) or Fitbit-only (control, n = 22). All received a Fitbit and 13 weeks of tailored weekly step goals. Tweet4Wellness consisted of a private Twitter support group, with daily automated behavior change "tweets" informed by behavior change theory, and encouragement to communicate within the group. Feasibility outcomes included recruitment and enrollment numbers, implementation challenges, and number and type of help requests from participants throughout the study period. Preliminary efficacy outcomes provided by Fitbit data were sedentary minutes, number of hours with >250 steps, maximum sitting bout, weighted sedentary median bout length, total steps, intensity minutes (>3.0 METS), and ratio of time spent sitting-to-moving. Acceptability outcomes included level of Twitter participation within Tweet4Wellness, and Likert scale plus open-ended survey questions on enjoyment and perceived effectiveness of intervention components. Survey data on acceptability of the features of the intervention were collected at 13 weeks (end-of-treatment [EOT]) and 22 weeks (follow-up). RESULTS: The study was feasible, with addressable implementation challenges. Tweet4Wellness participants changed significantly from baseline to EOT relative to control participants on number of active hours p = .018, total steps p = .028, and ratio of sitting-to-moving, p = .014. Only sitting-to-moving was significant at follow-up (p = .047). Among Tweet4Wellness participants, each tweet sent during treatment was associated with a 0.11 increase in active hours per day (p = .04) and a 292-step increase per day (p < .001). Tweet4Wellness participants averaged 54.8 (SD = 35.4) tweets, totaling 1304 tweets, and reported liking the accountability and peer support provided by the intervention. CONCLUSION: A Twitter-delivered intervention for promoting physical activity among inactive women from a heart clinic was feasible, acceptable, and demonstrated preliminary efficacy in increasing daily active hours, daily total steps, and the ratio of sitting-to-moving from pre to post for the intervention compared with the control. Lessons learned from this pilot suggest that the next study should expand the recruitment pool, refine the intervention to increase group engagement, and select active hours, total steps, and ratio of sitting-to-movement as primary sedentary behavior measures.

Dynamic regulation of the cancer stem cell compartment by Cripto-1 in colorectal cancer.

Stemness was recently depicted as a dynamic condition in normal and tumor cells. We found that the embryonic protein Cripto-1 (CR1) was expressed by normal stem cells at the bottom of colonic crypts and by cancer stem cells (CSCs) in colorectal tumor tissues. CR1-positive populations isolated from patient-derived tumor spheroids exhibited increased clonogenic capacity and expression of stem-cell-related genes. CR1 expression in tumor spheroids was variable over time, being subject to a complex regulation of the intracellular, surface and secreted protein, which was related to changes of the clonogenic capacity at the population level. CR1 silencing induced CSC growth arrest in vitro with a concomitant decrease of Src/Akt signaling, while in vivo it inhibited the growth of CSC-derived tumor xenografts and reduced CSC numbers. Importantly, CR1 silencing in established xenografts through an inducible expression system decreased CSC growth in both primary and metastatic tumors, indicating an essential role of CR1 in the regulation the CSC compartment. These results point to CR1 as a novel and dynamically regulated effector of stem cell functions in colorectal cancer.

Elimination of quiescent/slow-proliferating cancer stem cells by Bcl-XL inhibition in non-small cell lung cancer.

Lung cancer is the most common cause of cancer-related mortality worldwide, urging the discovery of novel molecular targets and therapeutic strategies. Stem cells have been recently isolated from non-small cell lung cancer (NSCLC), thus allowing the investigation of molecular pathways specifically active in the tumorigenic population. We have found that Bcl-XL is constantly expressed by lung cancer stem cells (LCSCs) and has a prominent role in regulating LCSC survival. Whereas chemotherapeutic agents were scarcely effective against LCSC, the small molecule Bcl-2/Bcl-XL inhibitor ABT-737, but not the selective Bcl-2 inhibitor ABT-199, induced LCSC death at nanomolar concentrations. Differently from gemcitabine, which preferentially eliminated proliferating LCSC, ABT-737 had an increased cytotoxic activity in vitro towards quiescent/slow-proliferating LCSC, which expressed high levels of Bcl-XL. In vivo, ABT-737 as a single agent was able to inhibit the growth of LCSC-derived xenografts and to reduce cancer stem cell content in treated tumors. Altogether, these results indicate that quiescent/slow-proliferating LCSC strongly depend on Bcl-XL for their survival and indicate Bcl-XL inhibition as a potential therapeutic avenue in NSCLC.

Changes in lifestyle improve body composition, thyroid function, and structure in obese children.

BACKGROUND: Alterations in thyroid function and structure have been reported in obesity. Function reverses to normal after weight loss, but nothing is known about structure. AIM: To evaluate the effect of weight loss on thyroid function and structure in obese children. SUBJECTS AND METHODS: The study was conducted in 72 overweight and obese children. Measurement of free T(3) (fT(3)), free T4 (fT(4)), TSH, antithyroid- antibodies and a thyroid ultrasound was performed at the beginning (phase 1) and after a period of 1.8±1.0 yr of lifestyle intervention (phase 2). RESULTS: Height SD score (SDS), body mass index SDS, total fat mass did not change from phase 1 to phase 2. Percentage of fat free mass decreased significantly (p<0.05). Waist/height ratio decreased (0.6±0.1 vs 0.5±0.1; p<0.05) as well as waist/hip ratio (0.9±0.1 vs 0.8±0.1; p<0.05). In phase 1, TSH was 2.8±1.7 mU/l; in phase 2, it was 2.2±0.9 mU/l (p<0.05); 17.2% of children showed a TSH level above the normal range (3.6 mU/l) in phase 1, and 6.2% in phase 2 (p<0.05). fT(4) was 10.8±2.2 pg/ml in phase 1 and 10.7±1.9 pg/ml in phase 2. fT(3) was 4.4±1.3 pg/ml (phase 1) and 3.9±1.1 pg/ml (phase 2) (p<0.05). Thyroid volume was -0.5±0.8 SDS (phase 1) and -0.5±1 SDS (phase 2). A non-significant improvement in thyroid structure was observed. CONCLUSIONS: In conclusion, healthier lifestyle improves body composition, thyroid function, and structure.

Fibrinogen kinetics and protein turnover in hypertension: Effects of insulin.

BACKGROUND AND AIM: Hyperfibrinogenemia, a cardiovascular risk factor, is frequent in hypertension and largely unexplained. In this study, we measured fibrinogen production and whole-body protein turnover under both basal and hyperinsulinemic states, in hypertensive [H] and control [C] subjects, using a leucine stable isotope tracer and precursor-product relationships. METHODS AND RESULTS: Since hypertension is often a feature of the "metabolic", insulin resistance syndrome, which in turn affects both fibrinogen kinetics and whole-body protein turnover, we selected hypertensive subjects without the metabolic syndrome. Following basal measurements, an euglycemic, approximately euaminoacidemic, hyperinsulinemic clamp was performed, with plasma insulin raised to 700-900 pmol/L. In H, rates of the fractional and absolute synthesis (FSR and ASR, respectively) of fibrinogen were 30%-40% greater (p<0.05 or less) than in C in both states, whereas leucine turnover was normal. Hyperinsulinemia did not modify fibrinogen synthesis in either group with respect to baseline, whereas it suppressed leucine appearance from endogenous proteolysis by approximately 40% to same extent in both groups. Amino acid clearance was similar in both the H and C subjects. In H, the insulin-mediated glucose disposal (M) was approximately 25% lower, (although insignificantly) than in controls, showing no overall insulin resistance. There was an inverse correlation between M and fibrinogen FSR during the clamp. CONCLUSIONS: In essential hypertension fibrinogen production is increased, is not further stimulated by insulin, and is inversely related to insulin sensitivity at high-physiological insulin concentrations. Amino acid disposal and basal as well as insulin-responsive protein degradation rates are instead normal.

Mild peripheral neuropathy prevents both leg muscular ischaemia and activation of exercise-induced coagulation in Type 2 diabetic patients with peripheral artery disease.

AIM: To study the influence of peripheral neuropathy on intermittent claudication in patients with Type 2 diabetes (T2DM). METHODS: Twenty-five patients with T2DM were grouped according to the ankle/brachial index (ABI): 10 with ABI > 0.9 without peripheral artery disease (PAD; group T2DM) and 15 with ABI < 0.9 with PAD (group T2DM + PAD). Twelve individuals without T2DM with PAD (group PAD without T2DM) were also enrolled. Tests for peripheral neuropathy were performed in all patients. ABI, rate pressure product, prothrombin fragments 1 + 2 (F1+2), thrombin-anti-thrombin complex (TAT), and d-dimer were measured before and after a treadmill test. During exercise both initial and absolute claudication distance and electrocardiogram readings were recorded. RESULTS: We found mild peripheral neuropathy in 20% of group T2DM and 46.7% of group T2DM + PAD (P < 0.01). After exercise, the rate pressure product increased in each group; ABI fell in T2DM + PAD (P < 0.0001) and in PAD without T2DM (P = 0.0005); the fall was greater in the latter group. Initial and absolute claudication distances were similar in PAD patients. In group T2DM + PAD, absolute claudication distance was longer in the subgroup without peripheral neuropathy (P < 0.05), whereas ABI and rate pressure products were similar. F1+2 values at rest were higher in group T2DM + PAD. After exercise, F1+2 values and TAT increased only in group PAD without T2DM. CONCLUSION: Only group PAD without T2DM experienced muscular ischaemia, whereas group T2DM + PAD did not. Mild peripheral neuropathy may have prevented them from reaching the point of muscular ischaemia during the treadmill test, because they stopped exercising with the early onset of pain. Reaching a false absolute claudication distance may induce ischaemic preconditioning. These findings suggest a possible protective role of mild peripheral neuropathy in T2DM patients with intermittent claudication, by preventing further activation of coagulation during treadmill testing.

Bisperoxovanadium, a phospho-tyrosine phosphatase inhibitor, reprograms myogenic cells to acquire a pluripotent, circulating phenotype.

Satellite cells are the main source of myogenic progenitors in postnatal skeletal muscle, but their use in cell therapy for muscle disorders is limited because these cells cannot be delivered through circulation and they are rapidly exhausted in severe myopathies. The search for alternative donor cells is ongoing, but none of the candidates so far show all the features required for successful colonization and repair of diseased muscle. In this study, we show that bisperoxovanadium, a phospho-tyrosine phosphatase inhibitor, induces myogenic cells to acquire a gene expression profile and a differentiation potential consistent with the phenotype of a circulating precursors, while maintaining their myogenic potential. These effects are mediated, at least in part, by NF-kappaB activation through the Tyr42-IkappaB-alpha phosphorylation, as shown by the expression of the dominant negative mutant form of the p50 NF-kappaB subunit. Moreover, when bisperoxovanadium-treated cells are injected into the femoral artery of alpha-sarcoglican null dystrophic mice, they are able to circulate and to reach muscle tissue; importantly, they contribute to muscle regeneration, as shown by the expression of alpha-sarcoglican in some fibers. Our observations indicate that bisperoxovanadium, or similar compounds, may prove very valuable to obtain and to expand, from committed cells, multipotent cell populations suitable for gene-cell therapy applications and may help to understand the molecular basis of genome reprogramming and "stem-ness."

[Nursing of intubation]. / Nursing dell'intubazione.

Recent developments in noninvasive ventilation allow the intensivists to delay the time o intubation of the patient admitted to the ICU. This new possibility of a gain in time leads to the fact that those patients who are intubated in the ICLI, are patients with a very compromised hemodynamic and respiratory situation. For this reason, we developed a specific protocol regarding the intubation procedure of this kind of patients. This paper reviews our strategies for endotracheal tube positioning in critically ill patients and shows the fundamental role of the nurses during this procedure.

[Nursing of tracheostomy]. / Nursing della tracheostomia.

In this abstract we have analyzed the different techniques of tracheostomy, considering new semplified methods of this procedure and therefore the common use of it in weaning from mechanical ventilation the critical care patients. We've tried to summarize guide lines of the preoperative, operative and postoperative procedures of tracheostomy, comparing our nursing clinical experience in ICU and the latest literature. We've primarily analyzed the nursing aspects of this issue, trying to focus on the priority of the treatment of the tracheostomezed patient.

Quality control of sedation for diagnostic radiological procedures in paediatric patients (waiting for guidelines).

BACKGROUND: The number of children requiring sedation for radiological procedures is increasing. Anaesthesiologists are increasingly involved in giving sedation or general anaesthesia in the rooms of the Radiology Department. This activity is not easy, and can be dangerous. The procedure is often performed on an ambulatory basis, so the child must be alert and discharged rapidly after the procedure. METHODS: We reviewed the medical charts of 488 patients in order to evaluate the incidence of complications during deep sedation for diagnostic radiological procedures. The patients were sedated with intravenous thiopental or propofol, or with oral chloral hydrate. All the patients were breathing spontaneously and received only supplemental O(2). RESULTS: We found only a few cases of complications, immediately treated without any recourse to tracheal intubation: respiratory failure with arterial desaturation to 94%, regurgitation, vomiting and persistent cough. CONCLUSIONS: On the basis of our experience, we believe that deep sedation with endovenous drugs guarantees safety and rapid discharge after the procedure.

Relationship of early carotid artery disease with lipoprotein (a), apolipoprotein B, and fibrinogen in asymptomatic essential hypertensive patients and normotensive subjects.

BACKGROUND: We investigated the relationships between plasma lipids and lipoprotein fractions and carotid artery lesions (CAL) in 177 cerebro-vascularly asymptomatic subjects, of whom 107 were primary hypertensive patients and 70 normotensive controls. METHODS: The prevalence and severity of CAL, as assessed by calculating a score of severity (score of CAL) and the maximal stenosis of both sides, as well as the intimal-medial thickness (IMT) were evaluated with a high-resolution echo-Doppler technique. We measured total serum cholesterol, triglycerides, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol, lipoprotein (a) [Lp(a)], Apo (apolipoprotein)AI, ApoAII, ApoB, and fibrinogen. RESULTS: Both the prevalence (59.4% vs 26.2%) and severity of sex- and age-adjusted and unadjusted CAL and IMT were significantly higher in hypertensive patients than in controls. Regression analysis showed different predictors of IMT and maximal stenosis. The variables that remained in the model were age, mean blood pressure (BP), and smoking for IMT; pulse pressure, known duration of hypertension (HT), fibrinogen, and ApoB for the score of CAL; and the last four variables along with age and mean BP for maximal stenosis. Furthermore, we identified a link between the atherogenic lipoprotein fractions Lp(a) and ApoB, fibrinogen and early carotid artery atherosclerotic changes. CONCLUSIONS: The different correlates of IMT, CAL, and maximal degree of stenosis suggest that they reflect different events occurring in the arterial wall in response to aging, HT, and other risk factors, rather than simply different stages of the same atherosclerotic process.

An IL-6/IL-6 soluble receptor (IL-6R) hybrid protein (H-IL-6) induces EPO-independent erythroid differentiation in human CD34(+) cells.

H-IL-6 is a hybrid protein constructed to contain IL-6 and its soluble receptor linked by a flexible peptide chain. Here we show that H-IL-6 strongly enhances proliferation of human CD34(+)cells in serum-free liquid culture, and that the majority of the cells generated belong to the erythroid lineage, being positive for the marker Glycophorin A. Conversely, H-IL-6 does not increase the number of myeloid, CD13-positive cells. Comparable effects are observed on progenitors from cord blood and adult peripheral blood. Therefore, H-IL-6 triggers an erythroid-inducing signal in haematopoietic progenitor cells, independently from erythropoietin (EPO).

Interleukin 6 knock-out mice are resistant to antigen-induced experimental arthritis.

In order to assess the potential role of IL-6 in rheumatoid arthritis (RA), we have compared IL-6 deficient (IL-6 ko) mice and their wild-type (wt) counterpart for the capacity to develop methylated bovine serum albumin (mBSA)-induced arthritis. Our data show that IL-6 ko mice are not susceptible to antigen-induced arthritis (AIA). In fact, IL-6 ko mice treated by a standard protocol of immunization with mBSA did not develop joint swelling following intra-articular mBSA injection, nor revealed the characteristic joint lesions by histological examination. Conversely, wt mice treated according to the same protocol developed arthritis about 9 days after intra-articular injection, as detected by knee joint swelling and histological confirmation. We observed that the proliferative response of splenocytes to mBSA was impaired in ko mice following arthritis induction, as compared to the strong response observed in wt mice. Furthermore, anti-mBSA IgG levels were lower in ko mice as compared to wt mice. Finally, we show that sensitivity to AIA can be reconstituted in ko mice by subcutaneous injections of recombinant human IL-6 (rhIL-6). In addition, co-administration of IL-6 with mBSA by intra-articular injection into the joint was only partially effective in conferring sensitivity to AIA, suggesting the importance of a systemic effct for IL-6, but also that an additional role for this cytokine can be envisaged in the local inflammatory reaction during establishment of AIA.

The usefulness of routine preoperative laboratory tests for one-day surgery in healthy children.

Since 1984, laboratory tests have not been routinely required for healthy paediatric patients scheduled for one-day surgery in our Paediatric Surgery Department. We reviewed the medical charts of all children ASA physical status 1 and 2 who underwent a minor surgical procedure in the last 15 years. We excluded all former preterm infants of less than 60 weeks postconceptual age. The series under examination includes two groups of patients: group A includes 1884 children who underwent routine preoperative laboratory tests; group B includes 8772 children who had preoperative, selected laboratory tests performed only when the child's history and/or clinical examination revealed some abnormalities. The following data were collected: demographic data, ASA physical status classification, surgical procedure, anaesthetic technique, major and minor complications, length of hospital stay, the difference between the expected length of hospitalization and the actual length, number and reasons for cancellations of surgery. On the basis of our experience we believe that a thorough clinical assessment of the patient is more important than routine preoperative laboratory screening, which should be required only when justified by real clinical indications. Moreover, this practice eliminates unnecessary costs without compromising the safety and the quality of care.

Mild proteolysis induces a ready-to-fuse state on Sendai virus envelope.

The Sendai virus fuses with host cell membranes in a pH-independent manner through an unknown mechanism. Here we report that mild trypsin pre-treatments of Sendai virions, for example 15 min at 4 degrees C, give Sendai virions the ability to fuse at a rate up to 10-fold higher than control. By using human erythrocytes as host cell membranes, viral fusion was assessed by hemolysis as well as fluorescence dequenching of octadecyl rhodamine B chloride. The mild protease treatment strikingly shortens the lag time taken by the virus to start the fusion process. Similar data were obtained on reconstituted Sendai virus envelope. Among proteases, tested as fusion enhancer, trypsin is more effective than either endoproteinase Lys-C, chymotrypsin, or endoproteinase Arg-C. After removal of trypsin from treated virions the fusion rate enhancement remains for hours at room temperature. The lack of protease specificity, together with the impossibility to detect any new N-terminal products, suggests that only a small percentage of viral envelope components are cleaved, still a large enough number to set the envelope in a ready-to-fuse state.

Human immunodeficiency virus (HIV)-resistant CD4+ UT-7 megakaryocytic human cell line becomes highly HIV-1 and HIV-2 susceptible upon CXCR4 transfection: induction of cell differentiation by HIV-1 infection.

Recent findings have shown that the expression of the seven trans-membrane G-protein-coupled CXCR4 (the receptor for the stromal cell-derived factor [SDF]-1 chemokine) is necessary for the entry of T-lymphotropic human immunodeficiency virus (HIV) strains, acting as a coreceptor of the CD4 molecule. In the human system, the role of CXCR4 in HIV infection has been determined through env-mediated cell fusion assays and confirmed by blocking viral entry in CD4+/CXCR4+ cells by SDF-1 pretreatment. We observed that the human megakaryoblastic CD4+ UT-7 cell line fails to express CXCR4 RNA and is fully resistant to HIV entry. Transfection of an expression vector containing the CXCR4 c-DNA rendered UT-7 cells readily infectable by different T-lymphotropic syncytium-inducing HIV-1 and HIV-2 isolates. Interestingly, HIV-1 infection of CXCR4 expressing UT-7 cells (named UT-7/fus) induces the formation of polynucleated cells through a process highly reminiscent of megakaryocytic differentiation and maturation. On the contrary, no morphologic changes were observed in HIV-2-infected UT-7/fus cells. These findings further strengthen the role of CXCR4 as a molecule necessary for the replication of T-lymphotropic HIV-1 and HIV-2 isolates and provide a useful model to study the functional role of CD4 coreceptors in HIV infection.

Isolation and biological characterization of two classes of blast-cell colony-forming cells from normal murine marrow.

In this study, a primitive progenitor cell, the blast-cell colony-forming cell (BC-CFC), which is thought by some to be equivalent to the hematopoietic stem cell (HSC), those cells capable of long-term marrow repopulation, has been isolated from normal murine marrow. The cell separation method we employed has, as its final step, the purification of marrow cells based on their ability to take up (bright) or exclude (dull) the mitochondrial dye, Rhodamine (Rho)-123. Rho-bright and Rho-dull cells are enriched for multipotential progenitor cells or for HSC, respectively. It was found that Rho-bright cells contain more BC-CFC than Rho-dull cells (310 +/- 50 v 120 +/- 40 per 10(5) purified cells, respectively). However, the BC-CFC that copurified with the Rho-bright and the Rho-dull cells were different in terms of replating efficiency and response to interleukin-3 (IL-3) and stem cell factor (SCF). In fact, on replating, the blast-cell colonies cultured from the Rho-dull population give rise to many more secondary colonies and had a greater replating efficiency than those obtained from Rho-bright cells (replating efficiency: 29.0 +/- 6.3 v 19.5 +/- 3.7, respectively, P < .01). Furthermore, while the same numbers of blast-cell colonies were detected in culture of Rho-bright cells stimulated with IL-3 alone or in combination with SCF, blast-cell colonies were generated in cultures of Rho-dull cells only in the presence of both IL-3 and SCF. After 5 days in suspension culture stimulated with IL-3 and SCF, Rho-dull cells generated BC-CFC whose replating potential was similar to the replating potential of BC-CFC contained in the Rho-bright population. These results indicate that BC-CFC contained in the Rho-bright and -dull populations are qualitatively different. Because the Rho-dull population contains HSC, the results indicate that few, if any, BC-CFC are HSC.

Circulating progenitor cells in human ontogenesis: response to growth factors and replating potential.

We have measured the number of progenitor cells circulating in fetal (17-32 weeks of gestation), perinatal (36 weeks of gestation), and adult (30-50 years old) blood. The progenitor cells at each ontogenetic stage were also characterized in terms both of the minimal combinations of growth factors they required to form maximal numbers of colonies in vitro and of their self-replication potential, as measured by the number of secondary and tertiary progenitor cells each could generate. The number of progenitor cells circulating in fetal and perinatal blood can be measured by directly plating the unfractionated blood. In this assay, fetal blood contains half the number of progenitor cells detected in perinatal blood (18.0 +/- 16.4 versus 40.88 +/- 0.63, p < 0.01), and the number of progenitor cells in adult blood is below the level of detection of the assay (< 1/8 microliter of blood). To compare the number of progenitor cells in all three stages of human development, progenitor cell counts were performed on blood mononuclear cells enriched by density separation. In this case, the light density cell fractions from fetal and neonatal blood contained the same number of progenitor cells (300/10(5) cells), numbers that were 10-fold higher than those observed with adult blood (30/10(5) cells). Circulating fetal-neonatal erythroid and multipotential progenitor cells were found to differ from their adult counterparts in terms of their response to growth factors and their self-renewal ability. In fact, the number of cytokines required to observe maximal colony formation increased with the ontogenetic stage of the cells. No differences were found in the frequency of primary colonies containing progenitor cells or in the mean number of secondary progenitor cells per primary colony in cultures of fetal, neonatal, or adult blood. Differences between the three ontogenetic stages, however, were found with respect to the number of sequential replatings that were possible. In fact, although both secondary granulocyte-macrophage (GM) and mixed-cell colonies derived from fetal cells gave rise to tertiary colonies, only perinatal secondary mixed-cell colonies grew in tertiary cultures, and no growth was observed in tertiary cultures of adult cells. These results suggest that the greater amplification of progenitor cells observed in liquid culture of fetal/neonatal versus adult blood is due both to a higher proliferative capacity of neonatal progenitor cells (up to two replatings versus one) and to a higher frequency in these samples of mixed-cell colony-forming cells (CFC) (37.7 +/- 7.3 versus 2.0 +/- 0.7/10(5) light density cells, respectively). Because of the high numbers of progenitor cells circulating in the fetus, as well as their high proliferative capacity, it is predicted that if blood could be harvested directly in utero, fetal blood would be as good a source of stem cells for transplantation as perinatal placental/cord blood. Circulating fetal stem cells would, therefore, represent an ideal target for gene therapy and in utero autologous transplantation.