Magnus Westgren

Immunomodulatory effects of human foetal liver-derived mesenchymal stem cells

Summary:Adult mesenchymal stem cells (MSCs) have been suggested to decrease lymphocyte proliferation in vitro. We hypothesised that foetal MSCs (fMSCs) would have an immunosuppressive effect on allograft responses in vitro. Human MSCs were isolated and cultured from first-trimester foetal livers and characterised by flow cytometry. fMSC stained positive for CD29, CD44, CD166, CD105, SH-3 and SH-4, and negative for CD14, CD34 and CD45. When plated on adipogenic, chondrogenic and osteogenic media, fMSC differentiated into the respective cell lineage. Compared to adult MSC (aMSC), the proliferative capacity of fMSC was higher. Mitogen stimulation of PBL was inhibited by fMSC. The greatest inhibition (78%) was seen when 30u2009000 fMSCs were added to 150u2009000 lymphocytes stimulated by phytohaemagglutinin. Adult and fMSCs were added to mixed lymphocyte cultures (MLC) containing peripheral blood lymphocytes or foetal liver cells. Unlike aMSC, fMSCs did not inhibit MLC. fMSC could be culture-expanded several million folds with no loss of phenotype characteristics, which makes them ideal for ex vivo expansion. fMSC inhibit lymphocyte proliferation induced by mitogens, but not alloreactivity as measured by MLC.

Cutting Edge: Identification and Characterization of Human Intrahepatic CD49a+ NK Cells

Although NK cells are considered innate, recent studies in mice revealed the existence of a unique lineage of hepatic CD49a+DX5− NK cells with adaptive-like features. Development of this NK cell lineage is, in contrast to conventional NK cells, dependent on T-bet but not Eomes. In this study, we describe the identification of a T-bet+Eomes−CD49a+ NK cell subset readily detectable in the human liver, but not in afferent or efferent hepatic venous or peripheral blood. Human intrahepatic CD49a+ NK cells express killer cell Ig-like receptor and NKG2C, indicative of having undergone clonal-like expansion, are CD56bright, and express low levels of CD16, CD57, and perforin. After stimulation, CD49a+ NK cells express high levels of inflammatory cytokines but degranulate poorly. CD49a+ NK cells retain their phenotype after expansion in long-term in vitro cultures. These results demonstrate the presence of a likely human counterpart of mouse intrahepatic NK cells with adaptive-like features.

Pre- and Postnatal Transplantation of Fetal Mesenchymal Stem Cells in Osteogenesis Imperfecta: A Two-Center Experience

Osteogenesis imperfecta (OI) can be recognized prenatally with ultrasound. Transplantation of mesenchymal stem cells (MSCs) has the potential to ameliorate skeletal damage. We report the clinical course of two patients with OI who received prenatal human fetal MSC (hfMSC) transplantation and postnatal boosting with same‐donor MSCs. We have previously reported on prenatal transplantation for OI type III. This patient was retransplanted with 2.8 × 106 same‐donor MSCs per kilogram at 8 years of age, resulting in low‐level engraftment in bone and improved linear growth, mobility, and fracture incidence. An infant with an identical mutation who did not receive MSC therapy succumbed at 5 months despite postnatal bisphosphonate therapy. A second fetus with OI type IV was also transplanted with 30 × 106 hfMSCs per kilogram at 31 weeks of gestation and did not suffer any new fractures for the remainder of the pregnancy or during infancy. The patient followed her normal growth velocity until 13 months of age, at which time longitudinal length plateaued. A postnatal infusion of 10 × 106 MSCs per kilogram from the same donor was performed at 19 months of age, resulting in resumption of her growth trajectory. Neither patient demonstrated alloreactivity toward the donor hfMSCs or manifested any evidence of toxicities after transplantation. Our findings suggest that prenatal transplantation of allogeneic hfMSCs in OI appears safe and is of likely clinical benefit and that retransplantation with same‐donor cells is feasible. However, the limited experience to date means that it is not possible to be conclusive and that further studies are required.

Fetal Membrane Cells for Treatment of Steroid-Refractory Acute Graft-Versus-Host Disease†‡§

The placenta protects the fetus from the mothers immune system. We have previously found that fetal membrane cells (FMCs) isolated from term placenta prevent alloreactivity in vitro. FMCs share many features with bone marrow‐derived mesenchymal stromal cells (MSCs), which we previously introduced to treat severe acute graft‐versus‐host disease (GVHD). Here, we tested FMCs for treatment of steroid‐refractory acute GVHD. After two passages in culture, approximately 109 FMCs were obtained from one single placenta, although not all cells from passage 0 and passage 1 were used for expansion. The FMCs were positive for CD29, CD44, CD73, CD90, CD105, and CD49d but were negative for hematopoietic, endothelial, and epithelial markers. Microsatellite polymorphism analysis showed that FMCs were of maternal origin. All FMCs used showed normal karyotype. Nine patients who had undergone hematopoietic stem cell transplantation (HSCT) and who had developed steroid‐refractory grade III–IV acute GVHD were given 0.9–2.8 × 106 FMCs per kg at 15 infusions. Median age was 57 years. There was no toxicity from infusion of FMCs in eight patients. One patient had seizures after infusion. Two of eight evaluable patients had a complete response and four had a partial response, giving an overall response rate of 75%. Two patients showed no response at all. Three patients are alive from 6 to 21 months after HSCT. One patient is well and two have chronic GVHD. Thus, FMCs may be successfully used for immune modulation and tissue repair. STEM CELLS2013;31:592–601

Late human cytomegalovirus (HCMV) proteins inhibit differentiation of human neural precursor cells into astrocytes.

Human cytomegalovirus (HCMV) is the most common cause of congenital infections in developed countries, with an incidence varying between 0.5–2.2%. Such infection may be the consequence of either a primary infection or reactivation of a latent infection in the mother and the outcome may vary from asymptomatic to severe brain disorders. Moreover, infants that are asymptomatic at the time of birth may still develop neurologic sequelae at a later age. Our hypothesis is that infection of stem cells of the central nervous system by HCMV alters the proliferation, differentiation or migration of these cells, and thereby gives rise to the brain abnormalities observed. We show that infection of human neural precursor cells (NPCs) with the laboratory strain Towne or the clinical isolate TB40 of HCMV suppresses the differentiation of these cells into astrocytes even at an multiplicity of infection (MOI) as low as 0.1 (by 33% and 67%, respectively). This inhibition required active viral replication and the expression of late HCMV proteins. Infection as late as 24 hr after the onset of differentiation, but not after 72 hr, also prevented the maturation of infected cultures. Furthermore, in cultures infected with TB40 (at an MOI of 1), approximately 54% of the cells were apoptotic and cell proliferation was significantly attenuated. Clearly, HCMV can reduce the capacity of NPCs to differentiate into astrocytes and this effect may provide part of the explanation for the abnormalities in brain development associated with congenital HCMV infection.

Stromal cells from term fetal membrane are highly suppressive in allogeneic settings in vitro.

Bone marrow‐derived mesenchymal stromal cells (BM‐MSCs) have immunosuppressive properties and have been used to treat steroid‐refractory acute graft‐versus‐host disease (GVHD) in stem cell transplant patients. Cells with similar capacities can also be found in term placental tissue. We have isolated stromal cells from term fetal membrane (FMSCs), umbilical cords (UCSCs) and placental villi (PVSCs) as well as from bone marrow and compared their immunoregulatory capacity in allogeneic settings. We found that FMSCs and UCSCs suppressed proliferation significantly in mixed lymphocyte reactions (MLRs), whereas PVSCs showed inconsistent suppressive effects. When added to MLR cultures, FMSCs suppressed the production of interferon (IFN)‐γ and interleukin (IL)‐17, whereas UCSCs and PVSCs promoted the production of IL‐17 instead. Secretion of IL‐10 was increased after addition of FMSCs and UCSCs. In this setting, BM‐MSCs had no significant effect on secretion of IFN‐γ, IL‐17 or IL‐10 in MLR cultures. When analysing the expression of adhesion markers, we noted that FMSCs expressed the highest levels of CD29 (β1), CD49d (α4) and CD54 (ICAM‐1) compared to the other types of stromal cells. Thus, our data indicate that stromal cells isolated from term fetal membrane have great immunosuppressive capacity in terms of proliferation and production of proinflammatory cytokines from alloreactive T cells, and also promote anti‐inflammatory IL‐10. They express high levels of integrins that may be of importance in homing to inflamed tissues. Fetal membrane may provide a valuable source of cells with immunosuppressive properties and could possibly be used for treatment of acute GVHD and other inflammatory disorders.

Moderate neonatal encephalopathy: Pre- and perinatal risk factors and long-term outcome

Background. The aim was to describe pre‐ and perinatal data and long‐term neurodevelopmental outcome (15–19 years) in children born at term with Apgar score <7 at 5 min and moderate neonatal encephalopathy. Methods. The study is based on a population‐based birth‐cohort of children born in Sweden in 1985. Maternal, delivery, neonatal, and neuropaediatric data were compiled. Neurodevelopmental status was classified according to the presence of 1. cerebral palsy or other major impairments, 2. exclusively cognitive impairments, and 3. no impairments. Results. The majority of the children (81%) had cognitive dysfunctions, with or without other impairments, such as cerebral palsy. The rates of post‐term birth (19% versus 8%) and breech presentation (12% versus 3%) were significantly higher than in the general Swedish population. Pre‐ and perinatal data did not differ notably between the three outcome groups. Questionable or suboptimal obstetric care was common (55%). Conclusions. The study shows that children born at term with moderate neonatal encephalopathy have a high rate of cognitive dysfunctions with or without cerebral palsy at long‐term follow‐up. Our pre‐ and perinatal data did not correlate with outcome.

Maternal microchimerism in human fetal tissues.

OBJECTIVEnThe aim of the present study was to analyze the presence of maternal cells in human fetal tissues in the second trimester.nnnSTUDY DESIGNnTissues from 11 second-trimester fetuses terminated because of social reasons or because of malformations and/or trisomy were investigated. By cell sorting and polymerase chain reaction amplification, we studied the presence of maternal CD3+, CD19+, CD34+, and CD45+ in different fetal tissues and in placenta.nnnRESULTSnIn the group of fetuses with normal karyotype and normal autopsy findings, 4 of 5 fetuses were positive for maternal microchimerism. In the group in which the fetuses were diagnosed with trisomy 21 and/or malformations, we found cells of maternal origin in 3 of 6 fetuses.nnnCONCLUSIONnThe results from this study indicate that maternal microchimerism is a common phenomenon in the second-trimester fetuses. Maternal cells of lymphoid and myeloid lineages and hematopoietic progenitors are widely distributed in the second-trimester fetuses.

EXPRESS study shows significant regional differences in 1-year outcome of extremely preterm infants in Sweden

The aim of this study was to investigate differences in mortality up to 1 year of age in extremely preterm infants (before 27 weeks) born in seven Swedish healthcare regions.

Comparison of ultrasound and autopsy findings in pregnancies terminated due to fetal anomalies

Objective. To compare antenatal diagnoses with autopsy findings in pregnancies terminated after ultrasound detection of fetal anomalies. A second aim was to study the quality of antenatal fetal diagnosis over time. Design. Retrospective, multicenter study over two consecutive six‐year periods in Uppsala and Stockholm. Setting. Cases were identified through fetal autopsy reports. Subjects. Three hundred and twenty‐eight fetuses from pregnancies terminated between 1992 and 2003 because of ultrasonographically diagnosed anomalies. Main outcome measures. The findings at the last ultrasound examination were compared with the autopsy reports. Results. In 299 cases (91.2%) ultrasound findings either exactly matched or were essentially similar to the autopsy findings. In 23 cases (7%) ultrasound findings were not confirmed at autopsy, but the postnatal findings were at least as severe as the antenatal ones. In six cases (1.8%) termination was performed for an anomaly which proved to be less severe than was predicted by ultrasound. The number of such cases was the same in both six‐year periods, while the total number of cases increased from 113 in the first to 215 in the second period. Fetal examination provided further diagnostic information in 47% of the cases. In 10% a syndrome was disclosed. Conclusion. Termination of pregnancy was not always based on a correct antenatal diagnosis. All fetuses but one from terminated pregnancies had evident anomalies. In six cases (1.8%) the decision to terminate was based on suboptimal prognostic and diagnostic information. Fetal autopsy by an experienced perinatal pathologist is essential to provide a definitive diagnosis.