Mothers' symptoms of anxiety and depression and the development of child temperament: A genetically informative, longitudinal investigation.

Background: Child temperament traits and mothers' emotional symptoms relating to anxiety and depression may drive changes in one another, leading to their 'co-development' across time. Alternatively, links between mother and child traits may be attributable to shared genetic propensities. We explored longitudinal associations between mothers' emotional symptoms and child temperament traits and adjusted for genetic effects shared across generations. Methods: This study is based on the Norwegian Mother, Father and Child Cohort Study (MoBa). Mothers (n = 34,060) reported on their symptoms of anxiety and depression, and temperament among offspring (n = 42,526), at child ages 1.5, 3 and 5 years. Structural equation models parameterised developmental change in traits, and an extended family design adjusted for genetic effects. Results: We found individual differences in stable trait scores and rate of change for all study variables. Longitudinal stability in mothers' emotional symptoms was associated with longitudinal stability in offspring emotionality (r = 0.143), shyness (r = 0.031), and sociability (r = -0.015). Longitudinal change in mothers' symptoms showed very small or negligible correlations with longitudinal change in child temperament. Both genetic and environmental influences explained the stable longitudinal association between mothers' symptoms and child emotionality. Conclusions: The studied associations between mother and child traits across time appeared to be due to stable, trait-like factors, involving genetic and environmental influence, rather than their co-development. Findings contribute knowledge on how emotional symptoms develop in families across time, and the methods with which we can explore such development.

The CODATwins Project: The Current Status and Recent Findings of COllaborative Project of Development of Anthropometrical Measures in Twins.

The COllaborative project of Development of Anthropometrical measures in Twins (CODATwins) project is a large international collaborative effort to analyze individual-level phenotype data from twins in multiple cohorts from different environments. The main objective is to study factors that modify genetic and environmental variation of height, body mass index (BMI, kg/m2) and size at birth, and additionally to address other research questions such as long-term consequences of birth size. The project started in 2013 and is open to all twin projects in the world having height and weight measures on twins with information on zygosity. Thus far, 54 twin projects from 24 countries have provided individual-level data. The CODATwins database includes 489,981 twin individuals (228,635 complete twin pairs). Since many twin cohorts have collected longitudinal data, there is a total of 1,049,785 height and weight observations. For many cohorts, we also have information on birth weight and length, own smoking behavior and own or parental education. We found that the heritability estimates of height and BMI systematically changed from infancy to old age. Remarkably, only minor differences in the heritability estimates were found across cultural-geographic regions, measurement time and birth cohort for height and BMI. In addition to genetic epidemiological studies, we looked at associations of height and BMI with education, birth weight and smoking status. Within-family analyses examined differences within same-sex and opposite-sex dizygotic twins in birth size and later development. The CODATwins project demonstrates the feasibility and value of international collaboration to address gene-by-exposure interactions that require large sample sizes and address the effects of different exposures across time, geographical regions and socioeconomic status.

Shared genetic influences do not explain the association between parent-offspring relationship quality and offspring internalizing problems: results from a Children-of-Twins study.

BACKGROUND: Associations between parenting and child outcomes are often interpreted as reflecting causal, social influences. However, such associations may be confounded by genes common to children and their biological parents. To the extent that these shared genes influence behaviours in both generations, a passive genetic mechanism may explain links between them. Here we aim to quantify the relative importance of passive genetic v. social mechanisms in the intergenerational association between parent-offspring relationship quality and offspring internalizing problems in adolescence. METHODS: We used a Children-of-Twins (CoT) design with data from the parent-based Twin and Offspring Study of Sweden (TOSS) sample [909 adult twin pairs and their offspring; offspring mean age 15.75 (2.42) years], and the child-based Swedish Twin Study of CHild and Adolescent Development (TCHAD) sample [1120 adolescent twin pairs; mean age 13.67 (0.47) years]. A composite of parent-report measures (closeness, conflict, disagreements, expressions of affection) indexed parent-offspring relationship quality in TOSS, and offspring self-reported internalizing symptoms were assessed using the Child Behavior Checklist (CBCL) in both samples. RESULTS: A social transmission mechanism explained the intergenerational association [r = 0.21 (0.16-0.25)] in our best-fitting model. A passive genetic transmission pathway was not found to be significant, indicating that parental genetic influences on parent-offspring relationship quality and offspring genetic influences on their internalizing problems were non-overlapping. CONCLUSION: These results indicate that this intergenerational association is a product of social interactions between children and parents, within which bidirectional effects are highly plausible. Results from genetically informative studies of parenting-related effects should be used to help refine early parenting interventions aimed at reducing risk for psychopathology.

Aetiological influences on stability and change in emotional and behavioural problems across development: a systematic review.

Emotional and behavioural problems in childhood and adolescence can be chronic and are predictive of future psychiatric problems. Understanding what factors drive the development and maintenance of these problems is therefore crucial. Longitudinal behavioural genetic studies using twin, sibling or adoption data can be used to explore the developmental aetiology of stability and change in childhood and adolescent psychopathology. We present a systematic review of longitudinal, behavioural genetic analyses of emotional and behavioural problems between ages 0 to 18 years. We identified 58 studies, of which 19 examined emotional problems, 30 examined behavioural problems, and 9 examined both. In the majority of studies, stability in emotional and behavioural problems was primarily genetically influenced. Stable environmental factors were also widely found, although these typically played a smaller role. Both genetic and environmental factors were involved in change across development. We discuss the findings in the context of the wider developmental literature and make recommendations for future research.

The relationship between parental depressive symptoms and offspring psychopathology: evidence from a children-of-twins study and an adoption study.

BACKGROUND: Parental depressive symptoms are associated with emotional and behavioural problems in offspring. However, genetically informative studies are needed to distinguish potential causal effects from genetic confounds, and longitudinal studies are required to distinguish parent-to-child effects from child-to-parent effects. METHOD: We conducted cross-sectional analyses on a sample of Swedish twins and their adolescent offspring (n = 876 twin families), and longitudinal analyses on a US sample of children adopted at birth, their adoptive parents, and their birth mothers (n = 361 adoptive families). Depressive symptoms were measured in parents, and externalizing and internalizing problems measured in offspring. Structural equation models were fitted to the data. RESULTS: Results of model fitting suggest that associations between parental depressive symptoms and offspring internalizing and externalizing problems remain after accounting for genes shared between parent and child. Genetic transmission was not evident in the twin study but was evident in the adoption study. In the longitudinal adoption study child-to-parent effects were evident. CONCLUSIONS: We interpret the results as demonstrating that associations between parental depressive symptoms and offspring emotional and behavioural problems are not solely attributable to shared genes, and that bidirectional effects may be present in intergenerational associations.

Aetiological overlap between obsessive-compulsive and depressive symptoms: a longitudinal twin study in adolescents and adults.

BACKGROUND: Depression is commonly co-morbid with obsessive-compulsive disorder (OCD). However, it is unknown whether depression is a functional consequence of OCD or whether these disorders share a common genetic aetiology. This longitudinal twin study compared these two hypotheses. METHOD: Data were drawn from a longitudinal sample of adolescent twins and siblings (n = 2651; Genesis 12-19 study) and from a cross-sectional sample of adult twins (n = 4920). The longitudinal phenotypic associations between OCD symptoms (OCS) and depressive symptoms were examined using a cross-lag model. Multivariate twin analyses were performed to explore the genetic and environmental contributions to the cross-sectional and longitudinal relationship between OCS and depressive symptoms. RESULTS: In the longitudinal phenotypic analyses, OCS at time 1 (wave 2 of the Genesis 12-19 study) predicted depressive symptoms at time 2 (wave 3 of the Genesis 12-19 study) to a similar extent to which depressive symptoms at time 1 predicted OCS at time 2. Cross-sectional twin analyses in both samples indicated that common genetic factors explained 52-65% of the phenotypic correlation between OCS and depressive symptoms. The proportion of the phenotypic correlation due to common non-shared environmental factors was considerably smaller (35%). In the adolescent sample, the longitudinal association between OCS at time 1 and subsequent depressive symptoms was accounted for by the genetic association between OCS and depressive symptoms at time 1. There was no significant environmental association between OCS and later depressive symptoms. CONCLUSIONS: The present findings show that OCS and depressive symptoms co-occur primarily due to shared genetic factors and suggest that genetic, rather than environmental, effects account for the longitudinal relationship between OCS and depressive symptoms.

pH is a potent modulator of erythroid differentiation.

Physiological parameters such as pH and oxygen tension probably play significant roles in the regulation of haemopoiesis in the bone marrow microenvironment, but these roles have yet to be characterized in detail. We have found that changes in culture pH (0.2 units) can cause significant changes in the culture composition of mature cells and colony-forming cells (CFCs), especially in the presence of erythropoietin (Epo). Peripheral blood (PB) CD34+ cells cultured at different pH values (7.15-7.6) were characterized using total cell counts, colony assays, morphological analysis. haemoglobin staining, flow cytometry, immunocytochemical staining, and Western blots. Cultures performed at high (7.6) pH contained greater numbers of haemoglobin-positive and band-3-positive cells. and acquired these erythroid differentiation markers sooner than standard (7.35) and low (7.1) pH cultures. Flow cytometry using CD71 and CD45RA antigens also indicated that erythroid differentiation proceeds faster at high pH and is blocked at an intermediate stage by low pH. Morphological data confirmed that high pH cultures had been shifted towards late-stage erythroid compartments as compared to low and standard pH cultures. These findings have important implications both in elucidating the regulatory role of pH in the bone marrow microenvironment and for the design of in vitro systems to study the development of erythroid cells.

Culture materials affect ex vivo expansion of hematopoietic progenitor cells.

Ex vivo expansion of hematopoietic cells is important for applications such as cancer treatment, gene therapy, and transfusion medicine. While cell culture systems are widely used to evaluate the biocompatibility of materials for implantation, the ability of materials to support proliferation of primary human cells in cultures for reinfusion into patients has not been addressed. We screened a variety of commercially available polymer (15 types), metal (four types), and glass substrates for their ability to support expansion of hematopoietic cells when cultured under conditions that would be encountered in a clinical setting. Cultures of peripheral blood (PB) CD34+ cells and mononuclear cells (MNC) were evaluated for expansion of total cells and colony-forming unit-granulocyte monocyte (CFU-GM; progenitors committed to the granulocyte and/or monocyte lineage). Human hematopoietic cultures in serum-free medium were found to be extremely sensitive to the substrate material. The only materials tested that supported expansion at or near the levels of polystyrene were tissue culture polystyrene, Teflon perfluoroalkoxy, Teflon fluorinated ethylene propylene, cellulose acetate, titanium, new polycarbonate, and new polymethylpentene. MNC were less sensitive to the substrate materials than the primitive CD34+ progenitors, although similar trends were seen for expansion of the two cell populations on the substrates tested. CFU-GM expansion was more sensitive to substrate materials than was total cell expansion. The detrimental effects of a number of the materials on hematopoietic cultures appear to be caused by protein adsorption and/or leaching of toxins. Factors such as cleaning, sterilization, and reuse significantly affected the performance of some materials as culture substrates. We also used PB CD34+ cell cultures to examine the biocompatibility of gas-permeable cell culture and blood storage bags and several types of tubing commonly used with biomedical equipment. While many of the culture bag materials gave satisfactory results, all of the tubing materials severely inhibited total cell and CFU-GM expansion. Taken together, our results show that many materials approved for blood contact or considered biocompatible are not suitable for use with hematopoietic cells cultured in serum-free medium. As hematopoietic cultures are scaled up for a variety of clinical applications, it will be essential to carefully examine the biocompatibility of all materials involved.

Variations in culture pH affect the cloning efficiency and differentiation of progenitor cells in ex vivo haemopoiesis.

Haemopoietic cultures may experience pH variations of as much as 0.5 units depending on culture duration and cell density. Since pH is a potent modulator of cellular proliferation and differentiation, we examined its effects on the performance of both semisolid and liquid haemopoietic cultures. Culture pH was found to have substantial effects both on progenitor cloning efficiency (as measured in liquid cultures) and on progenitor cell differentiation (as measured in methylcellulose cultures). Liquid cultures were conducted with both peripheral blood (PB) mononuclear cells (MNCs) and cord blood (CB) MNCs using growth factor combinations that promote either erythroid expansion (IL-3/IL-6/SCF/Epo) or granulocyte/macrophage expansion (IL-3/IL-6/SCF/G-CSF/GM-CSF). Reduced pH was found to have either a positive or neutral effect on the expansion and cloning efficiency of progenitors in ex vivo liquid cultures. Cloning efficiencies of PB BFU-E in the erythroid combination were 9-fold higher at low pH (7.1) when compared to high pH (7.6). A small pH increase of 0.2 units over physiological values consistently produced significant reductions (42-85%) in cloning efficiencies for all cell types and cytokine combinations tested. Methylcellulose cultures conducted using CB MNC and PB MNC indicated that differentiation of CFU-GM into progeny was optimal between pH 7.2 and 7.4. The differentiation of erythroid progenitors (BFU-E) progressively increased as pH was increased from 6.95 (no colonies detected) to 7.4 (maximum colonies detected), to 7.6 (maximum haemoglobin content). Methylcellulose cultures using PB CD34+ cells exhibited similar patterns to the MNC cultures. We conclude that even small variations in pH substantially affected the performance of human haemopoietic cultures. The erythroid lineage was particularly sensitive, with its extent of differentiation increasing with increasing pH. PB progenitors are more sensitive to pH variations than CB progenitors.

Comparison of whole serum-deprived media for ex vivo expansion of hematopoietic progenitor cells from cord blood and mobilized peripheral blood mononuclear cells.

A whole serum-deprived (WSD) medium was developed and optimized for expansion of colony-forming cells (CFC) in cord blood (CB) mononuclear cell (MNC) cultures. This medium was compared with four commercially available WSD media (commercial media), three WSD media whose compositions have been publicly disclosed (public media), two serum-containing media, and two basal media, for cell and CFC expansion in 10-day CB and mobilized peripheral blood (PB) MNC cultures supplemented with interleukin-3 (IL-3), IL-6, and stem cell factor (SCF). Selected WSD media and both serum-containing media gave significant CFC expansion in CBMNC and PBMNC cultures. The serum-containing human long-term medium gave the greatest cell (3.0-fold) and CFC (25-fold) expansions in CBMNC cultures, whereas our medium maintained the most cells (93% of input) and gave the greatest CFC expansion (6.1-fold) for PBMNC cultures. Of the commercial media, Progenitor-34 gave the greatest cell expansion (1.2-fold) and X VIVO-10 gave the greatest CFC expansion (11-fold) for CBMNC cultures, and Progenitor-34 maintained the most cells (83% of input) and gave the greatest CFC expansion (3.1-fold) for PBMNC cultures. Of the public media (including ours), our medium gave the greatest cell (1.4-fold) and CFC (6.1-fold) expansion for CBMNC cultures. Although there were slight correlations between cell and CFC expansion in 10-day CBMNC and PBMNC cultures (r2 of 0.848 and 0.594, respectively), the correlations did not give reliable predictions for medium selection. In addition, the different media favored expansion of different CFC types and performed differently for cultures using different cell sources (CB versus PB). Taken together, these results suggest that media must be carefully screened for the cell source to be cultured and the cell type(s) to be produced (e.g. total cells, CFC).

Hematopoietic cell culture therapies (Part II): Clinical aspects and applications.

High-dose chemotherapy, followed by hematopoietic stem cell transplantation, holds significant promise for increasing the probability of long-term remission and possibly cure in a variety of cancers. Hematopoietic cell culture, or ex vivo expansion of hematopoietic cells, may play a significant role in reducing the danger and expense associated with the transplantation procedure. Phase I clinical trials have shown that ex vivo expanded cells have no significant toxicities, and some benefits. Ex vivo expansion of hematopoietic cells is likely to find other applications in gene therapy, tumor purging, production of dendritic cells for immunotherapy and the production of mature blood cells for transfusion therapies.

Hematopoietic cell culture therapies (Part I): Cell culture considerations.

Hematopoietic cell culture, or ex vivo expansion of hematopoietic cells, is a rapidly growing area of tissue engineering with many potential applications in bone-marrow transplantation, gene therapy and the production of blood products. Hematopoietic cultures are considerably more complex than established animal cell culture technologies owing to the presence of many cell types at various differentiation stages, and stringent medium and growth factor requirements. Culture parameters, such as pH, oxygen tension, seeding density and feeding schedules, significantly affect the proliferation and differentiation of hematopoietic cells. A number of bioreactor systems are currently under development.

Ex vivo expansion of primitive hematopoietic cells for cellular therapies: An overview.

Sources of hematopoietic cells for bone marrow transplantation are limited by the supply of compatible donors, the possibility of viral infection, and autologous (patient) marrow that is depleted from prior chemo- or radiotherapy or has cancerous involvement. Anex vivo system to amplify hematopoietic progenitor cells could increase the number of patients eligible for autologous transplant, allow use of cord blood hematopoietic cells to repopulate an adult, reduce the amount of bone marrow and/or mobilized peripheral blood stem and progenitor cells required for transplantation, and reduce the time to white cell and platelet engraftment. The cloning of hematopoietic growth factors and the identification of appropriate conditions has enabled the development of successfulex vivo hematopoietic cell cultures. Purification systems based on the CD34 marker (which is expressed by the most primitive hematopoietic cells) have proven an essential tool for research and clinical applications. Present methods for hematopoietic cultures (HC) on stromal (i.e. accessory cells that support hematopoiesis) layers in flasks lack a well-controlled growth environment. Several bioreactor configurations have been investigated, and a first generation of reactors and cultures has reached the clinical trial stage. Our research suggests that perfusion conditions improve substantially the performance of hematopoietic reactors. We have designed and tested a perfusion bioreactor system which is suitable for the culture of non-adherent cells (without stromal cells) and readily scaleable for clinical therapies. Eliminating the stromal layer eliminates the need for a stromal cell donor, reduces culture time, and simplifies the culture system. In addition, we have compared the expansion characteristics of both mononuclear and CD34(+) cells, since the latter are frequently assumed to give a superior performance for likely transplantation therapies.