Encyclopedia
Biological differences between sexes should be considered in all stages of research, but there is still a lack of stratification by sex despite primary cultured cells retain memory of the sex and of the donor. The sex of donors in biological research must be known because variations in cells and cellular components can be used as end points, biomarkers and/or targets of pharmacological studies. This selective review focuses on the current findings regarding sex differences observed in the umbilical cord, a widely used source of research samples, both in the blood and in the circulating cells, as well as in the different cellular models obtainable from it. Moreover, an overview on sex differences in fetal programming is reported. As it emerges that the sex variable is still often forgotten in experimental models, we suggest that should be mandatory to adopt a sex oriented research, because only awareness of these issues can lead to innovative research.
- umbilical cord
- Sex differences
- preclinical research
Sex differences in umbilical cord
Human umbilical cord has no particular ethical impediments, is non-tumorigenic, and less immunogenic, representing an advantageous experimental source over other cell sources [24,25][1][2]. Moreover, it is a good experimental model for studying and understanding sex differences that characterize cardiovascular system [1][3]. The umbilical artery is made up of two main layers: an outer layer of muscle cells is found in a circular fashion and an inner layer with more irregularly available cells. Moreover, the umbilical cord contains Wharton's Jelly (WJ), a gelatinous substance made largely from mucopolysaccharides, which protects the blood vessels inside. WJ is enveloped in amniotic epithelium or, at the fetal end, a Malpighian keratinized epithelium, and it is a tissue that is active metabolically, involved in fluid exchange between umbilical vessels and amniotic fluid [83][4].
Sex-specific differences in fetus growth appear early in the pregnancy and have long been recognized [32][5]. Cell divisions is more rapid in male embryos than in female ones [33][6], and male fetuses growth seems to be greater than the female ones. Sex differences in the placenta are also described: globally males have larger and heavier placenta, and birth weight/placental weight ratio than females [44-46][7][8][9]. in addition, fetal sex may affect the outcome of pregnancies: male sex is a risk factor for adverse pregnancy outcome, including preterm birth, premature rupture of membranes, gestational diabetes and macrosomia, motor and cognitive outcomes, and a lower likelihood of survival in intensive care [44,60,61][7][10].
Several sex differences are reported in cord blood cells, plasma and serum (Table). As regard cellular models, some sex differences exist in HUVECs. In fact a higher rate of proliferation and migration, and higher levels of both the gene and protein for nitric oxide synthase 3 are observed in female cells than in male ones [15,116][11]. By contrast male HUVECs seems to have a higher degree of constitutive autophagy. Moreover, HUVECs from males resulted more apoptotic than female ones after serum starvation, while no significant sex differences were observed in the percentage of necrotic cells [119][12]. 70 genes are differentially expressed between the sexes: female HUVECs have a larger levels of genes related to the immune response and some genes involved in metabolism (for example, leptin, insulin receptors and some apolipoproteins), and that they also have a greater capacity to form tubes and tolerate the stress of serum deprivation better than their male counterparts [[13].
As regards HUAECs no sex-related differences have been reported at present and to our knowledge, probably because they are a less used source of endothelial cells. few results are available for HUASMCs: constitutive autophagy is similar between male and female HUASMCs, but they differently respond to pharmacological stimulations: serum starvation and rapamycin treatment (immunosuppressant and anticancer agent acting as a selective inhibitor of mTOR protein kinase, a pleiotropic agent in nutrient detection and signaling) [14] promote authophagy in both sexes, but especially in females cells increasing LC3II/I ratio and decreasing the phosphorylation of the autophagic regulator mTOR.
Significant higher gene expression of octamer-binding transcription factor 4 (OCT4), pluripotency gene, and the DNA-methyltransferase epigenetic modulator gene (DNMT1) was observed in male WJ-MSCs than in female ones, while no sex differences has been detected in the expression levels of other stemness regulating genes as SOX2, NANOG, and C-MYC [15]. Sex mayalso affect the potential and efficiency of WJ-MSCs differentiation and autophagy: no significant differences between males and females were observed for miR-14]5-5p (target: OCT4 gene), and miR-185-3p (target: DNMT1 gene), while miR-148a-3p (target: OCT4 gene) was significantly lower in males. In addition, the autophagic marker LC3II/I ratio was higher in female cells than in male ones, indicating a higher constitutive autophagy in female cells [16]. Another study showed that baculoviral IAP repeat-containing protein 2 (BIRC2) and BIRC3 genes, which inhibit apoptosis by interfering with the activation of caspases, are higher, although not significantly, in WJ stem cells from male newborns, indicating, perhaps a sex difference in the sensitivity to apoptosis [17].
As regards HUAECs no sex-related differences have been reported at present and to our knowledge, probably because they are a less used source of endothelial cells. few results are available for HUASMCs: constitutive autophagy is similar between male and female HUASMCs, but they differently respond to pharmacological stimulations: serum starvation and rapamycin treatment (immunosuppressant and anticancer agent acting as a selective inhibitor of mTOR protein kinase, a pleiotropic agent in nutrient detection and signaling) [133] promote authophagy in both sexes, but especially in females cells increasing LC3II/I ratio and decreasing the phosphorylation of the autophagic regulator mTOR.
Significant higher gene expression of octamer-binding transcription factor 4 (OCT4), pluripotency gene, and the DNA-methyltransferase epigenetic modulator gene (DNMT1) was observed in male WJ-MSCs than in female ones, while no sex differences has been detected in the expression levels of other stemness regulating genes as SOX2, NANOG, and C-MYC [141]. Sex mayalso affect the potential and efficiency of WJ-MSCs differentiation and autophagy: no significant differences between males and females were observed for miR-145-5p (target: OCT4 gene), and miR-185-3p (target: DNMT1 gene), while miR-148a-3p (target: OCT4 gene) was significantly lower in males. In addition, the autophagic marker LC3II/I ratio was higher in female cells than in male ones, indicating a higher constitutive autophagy in female cells [142]. Another study showed that baculoviral IAP repeat-containing protein 2 (BIRC2) and BIRC3 genes, which inhibit apoptosis by interfering with the activation of caspases, are higher, although not significantly, in WJ stem cells from male newborns, indicating, perhaps a sex difference in the sensitivity to apoptosis [143].
From this overview, it emerges that the sex variable is still often forgotten in experimental models. In fact, for some cell types, which may be important for understanding sex differences in the pathophysiology of the cardiovascular system, such as the one we have analyzed, there is no data. The knowledge of sex differences is fundamental to the improvement of therapeutic response at least for cardiovascular diseases in both men and women, as they are the main cause of mortality and morbidity for both sexes.
Table 1. Sex differences in cord blood, plasma and serum
|
Parameters |
Source |
M vs F |
Comments |
Ref |
|
Total and free testosterone |
serum (venous) |
> M |
Dehydroepiandrosterone sulfate from arterial serum > than that from vein only in F |
[86] |
|
Estradiol |
serum (venous) |
> M |
|
[86] |
|
Inhibin |
serum (venous) |
> M |
|
[86] |
|
Cortisol and corticosterone |
serum (arterial and venous) |
> F |
|
[96,97] |
|
GH |
serum (venous) |
> M |
|
[98] |
|
Leptin |
serum (arterial and venous) |
> F |
|
[92] |
|
Insulin and C-peptide |
plasma |
> F |
|
[99,100] |
|
15-F(2t)-isoprostane |
plasma |
> M |
Premature twins |
[93] |
|
Gluthatione |
umbilical cord vein |
> M |
Segments of umbilical cord vein perfused with tert-butylhydroperoxide |
[94] |
|
Mononuclear cell mitochondrial DNA copies |
cord blood |
> F |
After prenatal exposure to carbon monoxide as air pollutant |
[95] |
|
DNA methylation |
cord blood |
> F |
Number of methylated CpGs sites |
[105] |
|
Red blood cells |
cord blood |
> M |
|
[106,107] |
|
Hematocrit |
cord blood |
> M |
|
[106,107] |
|
Hemoglobin |
cord blood |
> M |
|
[106,107] |
|
Mean corpuscular hemoglobin concentration |
cord blood |
> M |
|
[106,107] |
|
Mean corpuscular volume |
cord blood |
> F |
|
[106,107] |
|
Platelet |
cord blood |
> F |
|
[106,107] |
|
White blood cells |
cord blood |
> F |
Lymphocyte, monocyte, eosinophil, basophil > M , neutrophil, metamyelocyte, myelocyte, and promyelocyte ratios > F |
[107] |
|
CD34+ progenitor cells |
cord blood |
> M |
M have higher capacity to produce colonies |
[108,109] |
|
ILC2s |
cord blood |
> M |
|
[110] |
|
CD34+KDR+ progenitor cells |
cord blood |
> F |
|
[111] |
|
Parameters |
Source |
M vs F |
Comments |
Ref |
|
Total and free testosterone |
serum (venous) |
> M |
Dehydroepiandrosterone sulfate from arterial serum > than that from vein only in F |
[18] |
|
Estradiol |
serum (venous) |
> M |
|
[18] |
|
Inhibin |
serum (venous) |
> M |
|
[18] |
|
Cortisol and corticosterone |
serum (arterial and venous) |
> F |
|
|
|
GH |
serum (venous) |
> M |
|
[21] |
|
Leptin |
serum (arterial and venous) |
> F |
|
[22] |
|
Insulin and C-peptide |
plasma |
> F |
|
|
|
15-F(2t)-isoprostane |
plasma |
> M |
Premature twins |
[25] |
|
Gluthatione |
umbilical cord vein |
> M |
Segments of umbilical cord vein perfused with tert-butylhydroperoxide |
[26] |
|
Mononuclear cell mitochondrial DNA copies |
cord blood |
> F |
After prenatal exposure to carbon monoxide as air pollutant |
[27] |
|
DNA methylation |
cord blood |
> F |
Number of methylated CpGs sites |
[28] |
|
Red blood cells |
cord blood |
> M |
|
|
|
Hematocrit |
cord blood |
> M |
|
|
|
Hemoglobin |
cord blood |
> M |
|
|
|
Mean corpuscular hemoglobin concentration |
cord blood |
> M |
|
|
|
Mean corpuscular volume |
cord blood |
> F |
|
|
|
Platelet |
cord blood |
> F |
|
|
|
White blood cells |
cord blood |
> F |
Lymphocyte, monocyte, eosinophil, basophil > M , neutrophil, metamyelocyte, myelocyte, and promyelocyte ratios > F |
[30] |
|
CD34+ progenitor cells |
cord blood |
> M |
M have higher capacity to produce colonies |
|
|
ILC2s |
cord blood |
> M |
|
[33] |
|
CD34+KDR+ progenitor cells |
cord blood |
> F |
|
[34] |
M = males; F = females
References
- Ribeiro, A.; Laranjeira, P.; Mendes, S.; Velada, I.; Leite, C.; Andrade, P.; Santos, F.; Henriques, A.; Graos, M.; Cardoso, C.M.; et al. Mesenchymal stem cells from umbilical cord matrix, adipose tissue and bone marrow exhibit different capability to suppress peripheral blood B, natural killer and T cells. Stem. Cell Res. Ther. 2013, 4, 125.
- Saleh, R.; Reza, H.M. Short review on human umbilical cord lining epithelial cells and their potential clinical applications. Stem. Cell Res. Ther. 2017, 8, 222.
- Legato, M.J. Principles of Gender-Specific Medicine. Gender in the Genomic Era, 3rd ed.; Elsevier Academic Press: Cambridge, MA, USA, 2017; p. 792.
- Tavares Fortuna, J.F.; Lourdes Pratas, M. Coarctation of the umbilical cord: A cause of intrauterine fetal death. Int. J. Gynaecol. Obstet. 1978, 15, 469–473.
- Gribnau, J.; Barakat, S.T. X-chromosome inactivation and its implications for human disease. bioRxiv 2017, 076950.
- Schmahl, J.; Eicher, E.M.; Washburn, L.L.; Capel, B. Sry induces cell proliferation in the mouse gonad. Development 2000, 127, 65–73.
- Almli, C.R.; Ball, R.H.; Wheeler, M.E. Human fetal and neonatal movement patterns: Gender differences and fetal-to-neonatal continuity. Dev. Psychobiol. 2001, 38, 252–273.
- DiPietro, J.A.; Hodgson, D.M.; Costigan, K.A.; Hilton, S.C.; Johnson, T.R. Fetal neurobehavioral development. Child. Dev. 1996, 67, 2553–2567.
- Oreal, E.; Mazaud, S.; Picard, J.Y.; Magre, S.; Carre-Eusebe, D. Different patterns of anti-Mullerian hormone expression, as related to DMRT1, SF-1, WT1, GATA-4, Wnt-4, and Lhx9 expression, in the chick differentiating gonads. Dev. Dyn. 2002, 225, 221–232.
- Widnes, C.; Flo, K.; Wilsgaard, T.; Kiserud, T.; Acharya, G. Sex differences in umbilical artery Doppler indices: A longitudinal study. Biol. Sex Differ. 2018, 9, 16. Dawes, N.W.; Dawes, G.S.; Moulden, M.; Redman, C.W. Fetal heart rate patterns in term labor vary with sex, gestational age, epidural analgesia, and fetal weight. Am. J. Obstet. Gynecol. 1999, 180, 181–187.
- Maschietto, M.; Bastos, L.C.; Tahira, A.C.; Bastos, E.P.; Euclydes, V.L.; Brentani, A.; Fink, G.; de Baumont, A.; Felipe-Silva, A.; Francisco, R.P.; et al. Sex differences in DNA methylation of the cord blood are related to sex-bias psychiatric diseases. Sci. Rep. 2017, 7, 44547.
- Zhou, L.; Che, Z.; Zhang, X.; Zhou, P.; Li, X.; Xu, X.; Shi, Q.; Li, D.; Ju, X. Influence of neonatal gender on cord blood CD34(+) cell amplification and gene expression. Exp. Ther. Med. 2019, 18, 105–118.
- Cines, D.B.; Pollak, E.S.; Buck, C.A.; Loscalzo, J.; Zimmerman, G.A.; McEver, R.P.; Pober, J.S.; Wick, T.M.; Konkle, B.A.; Schwartz, B.S.; et al. Endothelial cells in physiology and in the pathophysiology of vascular disorders. Blood 1998, 91, 3527–3561.
- Toth, B.; Saadat, G.; Geller, A.; Scholz, C.; Schulze, S.; Friese, K.; Jeschke, U. Human umbilical vascular endothelial cells express estrogen receptor beta (ERbeta) and progesterone receptor A (PR-A), but not ERalpha and PR-B. Histochem. Cell Biol. 2008, 130, 399–405.
- Oettel, A.; Lorenz, M.; Stangl, V.; Costa, S.D.; Zenclussen, A.C.; Schumacher, A. Human umbilical vein endothelial cells foster conversion of CD4+CD25-Foxp3- T cells into CD4+Foxp3+ regulatory T cells via Transforming Growth Factor-beta. Sci. Rep. 2016, 6, 23278.
- Lavoie, J.C.; Chessex, P. Gender and maturation affect glutathione status in human neonatal tissues. Free Radic. Biol. Med. 1997, 23, 648–657.
- Hartman, R.J.G.; Kapteijn, D.M.C.; Haitjema, S.; Bekker, M.N.; Mokry, M.; Pasterkamp, G.; Civelek, M.; den Ruijter, H.M. Intrinsic transcriptomic sex differences in human endothelial cells at birth and in adults are associated with coronary artery disease targets. Sci. Rep. 2020, 10, 12367.
- Kim, D.W.; Staples, M.; Shinozuka, K.; Pantcheva, P.; Kang, S.D.; Borlongan, C.V. Wharton’s jelly-derived mesenchymal stem cells: Phenotypic characterization and optimizing their therapeutic potential for clinical applications. Int. J. Mol. Sci. 2013, 14, 11692–11712.
- Barnwal, M.; Rathi, S.; Chhabra, S.; Nanda, S. Histomorphometry of umbilical cord and its vessels in pre- eclampsia as compared to normal pregnancies. Nepal J. Obstet. Gynaecol. 2013, 7, 28–32.
- Rua Ede, A.; Porto, M.L.; Ramos, J.P.; Nogueira, B.V.; Meyrelles, S.S.; Vasquez, E.C.; Pereira, T.C. Effects of tobacco smoking during pregnancy on oxidative stress in the umbilical cord and mononuclear blood cells of neonates. J. Biomed. Sci. 2014, 21, 105.
- Milnerowicz-Nabzdyk, E.; Zimmer, M.; Tlolka, J.; Michniewicz, J.; Pomorski, M.; Wiatrowski, A. Umbilical cord morphology in pregnancies complicated by IUGR in cases of tobacco smoking and pregnancy-induced hypertension. Neuro Endocrinol. Lett. 2010, 31, 842–847.
- Heifetz, S.A. Single umbilical artery. A statistical analysis of 237 autopsy cases and review of the literature. Perspect. Pediatr. Pathol. 1984, 8, 345–378.
- Broere-Brown, Z.A.; Adank, M.C.; Benschop, L.; Tielemans, M.; Muka, T.; Goncalves, R.; Bramer, W.M.; Schoufour, J.D.; Voortman, T.; Steegers, E.A.P.; et al. Fetal sex and maternal pregnancy outcomes: A systematic review and meta-analysis. Biol. Sex Differ. 2020, 11, 26.
- Mittelstrass, K.; Ried, J.S.; Yu, Z.; Krumsiek, J.; Gieger, C.; Prehn, C.; Roemisch-Margl, W.; Polonikov, A.; Peters, A.; Theis, F.J.; et al. Discovery of sexual dimorphisms in metabolic and genetic biomarkers. PLoS Genet. 2011, 7, e1002215.
- Lilja, M. Infants with single umbilical artery studied in a national registry. General epidemiological characteristics. Paediatr. Perinat. Epidemiol. 1991, 5, 27–36.
- Chitra, T.; Sushanth, Y.S.; Raghavan, S. Umbilical coiling index as a marker of perinatal outcome: An analytical study. Obstet. Gynecol. Int. 2012, 2012, 213689.
- Ochshorn, Y.; Ascher Landsberg, J.; Many, A.; Maslovitz, S.; Rimon, E.; Yogev, Y. Fetal gender and umbilical cord characteristics at birth. J. Matern. Fetal Neonatal Med. 2019, 1–4.
- Reuter, S.E.; Evans, A.M.; Chace, D.H.; Fornasini, G. Determination of the reference range of endogenous plasma carnitines in healthy adults. Ann. Clin. Biochem. 2008, 45, 585–592.
- Simmons, D.; France, J.T.; Keelan, J.A.; Song, L.; Knox, B.S. Sex differences in umbilical cord serum levels of inhibin, testosterone, oestradiol, dehydroepiandrosterone sulphate, and sex hormone-binding globulin in human term neonates. Biol. Neonate 1994, 65, 287–294.
- Wynne-Edwards, K.E.; Lee, K.; Zhou, R.; Edwards, H.E. Sex differences in substrates and clearance products of cortisol and corticosterone synthesis in full-term human umbilical circulation without labor: Substrate depletion matches synthesis in males, but not females. Psychoneuroendocrinology 2019, 109, 104381.
- Giesbrecht, G.F.; Rash, J.A.; Edwards, H.E.; Wynne-Edwards, K.E. Full-term deliveries without antecedent labor reveal sex differences in umbilical cord glucocorticoid concentrations. Psychoneuroendocrinology 2016, 74, 121–125.
- Fukaya, T.; Furuhashi, N.; Kono, H.; Tachibana, Y.; Shinkawa, O.; Takahashi, T.; Suzuki, M. Secretion and Sex differences in cord serum growth hormone levels of the human fetus (author’s transl). Nihon Sanka Fujinka Gakkai Zasshi 1982, 34, 491–496.
- Kuchay, M.S.; Kudyar, R.P.; Gupta, A.; Pandita, K.K.; Ganie, M.A. Gender differences in insulin and C-peptide concentrations at birth using cord blood collection. Arch. Endocrinol. Metab. 2016, 60, 264–266.
- Shields, B.M.; Knight, B.; Hopper, H.; Hill, A.; Powell, R.J.; Hattersley, A.T.; Clark, P.M. Measurement of cord insulin and insulin-related peptides suggests that girls are more insulin resistant than boys at birth. Diabetes Care 2007, 30, 2661–2666.
