Human umbilical cord (HUC) is a suitable source for isolation of endothelial cells (ECs) since it has no particular ethical impediments and is considered a non-tumorigenic and less immunogenic model. for this reason, HUC represents an advantageous experimental source for the isolation of endothelial cells. The ECs can produce/release molecules that modulate vasoconstriction and vasorelaxation by smooth muscle cells (SMC).
Cardiovascular diseases (CVD) constitute the major cause of death worldwide, with a higher prevalence in the adult population [1][2]. Examples of CVD are coronary artery disease, peripheral arterial disease, or aortic disease.
Currently, the human umbilical cord (HUC) is a suitable source for isolation of endothelial cells (ECs) since it has no particular ethical impediments and is considered a non-tumorigenic and less immunogenic model. for this reason, HUC represents an advantageous experimental source for the isolation of endothelial cells [3]. The ECs can produce/release molecules that modulate vasoconstriction and vasorelaxation by smooth muscle cells (SMC) [4][5]. When releasing nitric oxide (NO), prostacyclin, bradykinin, and endothelium-derived hyperpolarizing factor (EDHF), the response given will be vasodilation by the SMC. If the substances released are endothelin-1 (ET-1), angiotensin II (Ang II), thromboxane A2 (TXA2), the final effect is vasoconstriction by the SMC [6].
The effect of endothelium in vivo is very difficult to study. To counteract this, several in vitro techniques were developed. Among these techniques, the use of human umbilical vein endothelial cells (HUVECs) was widely used as a source of human endothelial cells because they have some advantages. The main advantage is that it is obtained from non-pathogenic human tissues, which is not the case with other human sources, and the physiological relevance in the control of vascular pathways. Moreover, primary cultures with these cells can maintain native characteristics of endothelial cells and their intracellular signaling pathways [7].
From a physiological point of view, the human umbilical cord (HUC) is a channel developed from the amniotic sac (which forms the epithelium), the allantois (which forms the umbilical veins and arteries), and the yolk sac [8][9].
Thus, not only the number of blood vessels but also morphological changes can contribute to the development of pathologies. We can conclude that the presence or absence of blood vessels is of extreme importance for the development of pathology.
In summary, not only the number of blood vessels but also morphological changes can contribute to the development of pathologies.
Finally, HUA does not have vasa vasorum or a nervi vasorum, nor a typical external tunica (adventitia). The function of this tunica is performed by Wharton’s jelly (mucous connective tissue and fibroblasts) which is surrounded by nutritional vessels and rich in glycosaminoglycans [8][10][11].
During the last 3 decades, advances in vascular endothelial cell biology have had a great impact on the understanding of some pathophysiological conditions such as cardiovascular diseases [12][13]. Between 1922 and 1973, there was a growing interest among the scientific community in human umbilical cord vein-derived endothelial cells (HUVEC) for these investigations [1]. In 1922, studies were conducted and described the development of endothelial cells from chicken liver embryonic tissue explants [14].
In 1973, Eric A. Jaffe successfully isolated HUVEC, which grew as a homogeneous monolayer of polygonal cells with well-defined borders. Furthermore, these authors also compared HUVECs with SMC and fibroblasts, which allowed them to conclude that HUVECs contained rod-shaped cytoplasmic organelles [15]. In this procedure, veins were perfused with collagenase and incubated for 15 min at 37 °C, and endothelial cells were collected at the end [15].
Since 1974, some studies of isolation of EC have appeared intending to study the physiology of EC, most of them based on the studies and descriptions made by the following authors [16][17][18][19]. Over time, these studies have undergone some adaptations, such as the constitution of the culture medium for endothelial cells. In this sense, the constitution of the culture medium used may contain endothelial cell growth factor (ECGF), which allows long-term growth of the ECs, or an anti-PPLO agent that prevents contamination by gram-positive bacteria or mycoplasmas [17][20][21][22][23]. Culture media containing 5 ng/mL epidermal growth factor (EGF) was shown to have a higher proliferative potential compared to the anti-pleuropneumonia-like organisms’ agent (anti-PPLO agent).
Meanwhile, some authors performed with the same umbilical cord the culture of HUVECs and the culture of HUAECs, and observed that cell isolation by enzymatic digestion is easy and fast when the artery and vein are used from a single umbilical cord [18]. Furthermore, other authors performed the isolation of the HUVECs and the HUCMSC (umbilical cord mesenchymal stem cells) from the same umbilical cord [24], as shown in Table 1 . The culture of HUCMSC may also allow us to direct the fate towards an endothelial cell lineage, which can represent economical and commercially viable option manly for cell replacement therapy due to its noninvasive collection procedure [24].
This entry is adapted from the peer-reviewed paper 10.3390/biologics1020015