Cultivation of arterial endothelial cells from human umbilical cord

A simple and biosafe method for isolation of human umbilical vein endothelial cells

Human umbilical vein endothelial cells (HUVECS) are used as an irreplaceable tool for the study of vascular diseases. However, the technicians who isolate HUVECs are largely exposed to potential infectious threats. Here we report the development of a specialized instrument to protect researchers from known or unknown infectious agents when they operate on human umbilical cords. This instrument can be assembled by common laboratory supplies and adapted to accommodate umbilical cords of different lengths. When the cord is enclosed within the instrument, the risk of sample contamination and operator infection is greatly reduced. Using our instrument, endothelial cells were successfully isolated from human umbilical veins without contamination. The cells were verified by their cobblestone-like morphology and by immunofluorescence staining (Factor VIII and CD31 positivity and α-SMA negativity). Our instrument simplifies and optimizes the cell extraction process, and most importantly elevates the biosafety to a higher level during the isolation of human umbilical vein endothelial cells.

Early vascular phenotypes in the genesis of hypertension

Cardiovascular complications occurring in adults find their roots in risk factors operating early in life. Among the factors influencing cardiovascular risk, blood pressure values in children represent an important measurable marker of the level of potential cardiovascular risk later in life because the levels are both the cause and the consequence of early vascular alterations. Early vascular phenotypes represent a field of great interest, and they can be studied through indirect assessment using non-invasive techniques. Estimations of blood pressure components, pulse wave velocity, and reflecting waves provide valuable information that can be easily recorded and repeated overtime. A direct assessment, carried out by examining the umbilical vessels, can add further valuable information. In this review, we discuss the potential application of surrogate markers of early vascular alterations and describe the information provided by umbilical cord vessels.

Birth weight and characteristics of endothelial and smooth muscle cell cultures from human umbilical cord vessels

Background

Low birth weight has been related to an increased risk for developing high blood pressure in adult life. The molecular and cellular analysis of umbilical cord artery and vein may provide information about the early vascular characteristics of an individual. We have assessed several phenotype characteristics of the four vascular cell types derived from human umbilical cords of newborns with different birth weight. Further follow-up studies could show the association of those vascular properties with infancy and adulthood blood pressure.

Methods

Endothelial and smooth muscle cell cultures were obtained from umbilical cords from two groups of newborns of birth weight less than 2.8 kg or higher than 3.5 kg. The expression of specific endothelial cell markers (von Willebrand factor, CD31, and the binding and internalization of acetylated low-density lipoprotein) and the smooth muscle cell specific α-actin have been evaluated. Cell culture viability, proliferation kinetic, growth fraction (expression of Ki67) and percentage of senescent cells (detection of β-galactosidase activity at pH 6.0) have been determined. Endothelial cell projection area was determined by morphometric analysis of cell cultures after CD31 immunodetection.

Results

The highest variation was found in cell density at the confluence of endothelial cell cultures derived from umbilical cord arteries (66,789 ± 5,093 cells/cm² vs. 45,630 ± 11,927 cells/cm², p < 0.05). Morphometric analysis indicated that the projection area of the artery endothelial cells (1,161 ± 198 and 1,544 ± 472 μm², p < 0.05), but not those derived from the vein from individuals with a birth weight lower than 2.8 kg was lower than that of cells from individuals with a birth weight higher than 3.5 kg.

Conclusion

The analysis of umbilical cord artery endothelial cells, which demonstrated differences in cell size related to birth weight, can provide hints about the cellular and molecular links between lower birth weight and increased adult high blood pressure risk.

A protocol for isolation and culture of human umbilical vein endothelial cells

We describe a protocol for easy isolation and culture of human umbilical vein endothelial cells (HUVECs) to supply every researcher with a method that can be applied in cell biology laboratories with minimum equipment. Endothelial cells (ECs) are isolated from umbilical vein vascular wall by a collagenase treatment, then seeded on fibronectin-coated plates and cultured in a medium with Earles' salts and fetal calf serum (FCS), but without growth factor supplementation, for 7 days in a 37 degrees C-5% CO2 incubator. Cell confluency can be monitored by phase-contrast microscopy; ECs can be characterized using cell surface or intracellular markers and checked for contamination. Various protocols can be applied to HUVECs, from simple harvesting to a particular solubilization of proteins for proteomic analysis.

Achieving the ideal properties for vascular bypass grafts using a tissue engineered approach: a review

The multiple demands placed on small calibre cardiovascular bypass grafts have meant that a synthetic prosthesis with good long-term patency has not been developed. A tissue-engineered graft could fulfil the ideal characteristics present in an artery. However, the great disadvantage of such a conduit is the time necessary for maturation leading to unacceptable delays once the decision to intervene surgically has been made. This maturation process is essential to produce a graft which can withstand haemodynamic stress. Once implanted, the tissue-engineered graft can contract in response to immediate haemodynamic conditions and remodel in the long term. We review the latest tissue engineering approaches used to give the favourable properties of mechanical strength, arterial compliance, low thrombogenicity, long-term resistance towards biodegradation as well as technological advances which shorten the time required for production of an implantable graft.

Procedure to consistently obtain endothelial and smooth muscle cell cultures from umbilical cord vessels

The prenatal history of an individual can be responsible to some extent for the occurrence of several diseases later in life. Thus, low birth weight has been related to an increased risk of developing hypertension or type 2 diabetes. The molecular and cellular basis of this increased risk could be found in body fluids and cell types that can be obtained just after birth. To get this unique information, a methodology was developed to consistently obtain cultures of 4 cell types, endothelial and smooth muscle cells from both the vein and the arteries present in the umbilical cord of an individual. From 21 umbilical cords processed, 82 of the 84 possible cell cultures were obtained. The cell cultures exhibit the expected cell morphology and cellular characteristics. Thus, endothelial cells express the von Willebrand factor, CD31, as well as bind and internalize acetylated low-density lipoprotein. Vascular smooth muscle cells express the distinctive alpha-actin. Cell cultures can be cryopreserved and grow healthy for several passages. No influence of birth weight of the newborn has been found in the time required to obtain a primary cell culture for any of the 4 cell types. In conclusion, the procedure developed allows one to routinely obtain actively growing vascular cell cultures that could be used to study the molecular and cellular basis of vascular diseases that emerge in adulthood.

Different characteristics of endothelial cells from central and peripheral human cornea in primary culture and after subculture

Several methods for isolation and cultivation of human corneal endothelial cells have been described during the last few decades. In contrast to the situation in vivo, the cultured cells show mitogenic activity but often lose their typical morphological appearance. In this paper, we describe a technique to isolate and cultivate morphologically unchanged endothelium from the human cornea. This method revealed different characteristics of endothelial cells according to their position within the human cornea. Endothelial cells isolated from the central part have a morphology similar to that of cells in vivo (i.e., they are densely packed and show no mitogenic activity). In contrast, endothelial cells derived from the peripheral part of the cornea are characterized by mitogenic activity but their cell-to-cell attachment seems to be less tight than in vivo. The significance of these two different endothelial cell types for wound healing in the human cornea is discussed.

Inhibition of in vitro angiogenesis by lymphotoxin and interferon-gamma

The effects of lymphotoxin (LT) and interferon (IFN)-gamma on the capillary formation was examined using an in vitro angiogenesis model system. Both LT and IFN-gamma inhibited the capillary formation in a dose dependent manner. To elucidate the mode of action, effects of the lymphokines on endothelial and myofibroblastic cells were studied. We found that the lymphokines inhibited not only the growth of endothelial cells but also the production of collagen by myofibroblastic cells. These results suggest that the pleiotropic effects of the lymphokines on different types of cells might result in the inhibition of the capillary formation.

Development of capillary networks from rat microvascular fragments in vitro: the role of myofibroblastic cells

A new model useful for studying capillary growth in vitro is described. When the microvessel fragments and accompanying single cells (myofibroblastic cells) from rat epididymal fat pads were co-cultivated, the myofibroblastic cells initially began to grow and reached confluence. A few days later, endothelial cells started to sprout from the vessel fragments, forming cellular cord networks on and in the multilayered myofibroblastic cells. Ultrastructurally, the lumina, surrounded by the endothelial cells having intercellular junctions, were observed at cross-sectioned cellular cords. The growth of cellular cords from the fragments always occurred after the myofibroblastic cells had reached confluence. The medium conditioned to isolated rat myofibroblastic cells stimulated not only the proliferation of the endothelial cells from the bovine capillary and human vein but also the migration of bovine capillary endothelial cells in vitro. Moreover, the extracellular matrix produced by rat myofibroblastic cells modulated the morphology of bovine capillary endothelial cells to a cordlike shape. These observations strongly suggest that the formation of the capillary in vitro is induced by myofibroblastic cells.

Human endothelial cell cultures: phenotypic modulation by leukocyte interleukins

We report here that soluble factors from activated mononuclear leukocytes have a dramatic effect on cultured endothelial cells. While human umbilical vein endothelial cells grown under standard conditions show a polygonal, epithelial-like morphology, cells exposed to culture media conditioned by lectin-activated human mononuclear leukocytes become extremely elongated and/or send out numerous cytoplasmic processes, assuming a dendritic configuration. This effect cannot be mimicked by exogenous cyclic AMP, is reversible upon interruption of the treatment, and appears specific for endothelial cells, since it has not been observed so far with other cell types. The shape changes are accompanied by a reorganization of the endothelial cell cytoskeleton: actin microfilament bundles tend to be disposed in parallel arrays, while intermediate filaments and microtubules penetrate up to the extremity of the cytoplasmic processes. Colchicine prevents endothelial cell elongation but only slightly impairs the formation of lateral cell processes ("dendritic configuration"). Purified interleukins were tested for their ability to induce these changes of cell shape. Escherichia coli-recombinant human interleukin 2 had no effect, and gamma-interferon only a slight effect on endothelial cell morphology. Interleukin 1 induced moderate cell elongation, while combined treatment with both interleukin 1 and gamma-interferon resulted in shape changes indistinguishable from those elicited by supernatants of activated mononuclear leukocytes. The possible relevance of the observed endothelial cell changes to the reported angiogenic activity of mononuclear cell products is discussed.