Compare endothelial cells and epithelial cells and their differences

Endothelial cells cover the inner surface of the blood vessel, and epithelial cells cover the inner surface of the internal organs. The epithelial cells also cover the outer surface of the human body. If a large number of epithelial cells are found in the urine during urine testing, it indicates a urinary tract infection.

The endothelial cells and epithelial cells that make up the tissue are derived from the epithelium, but the two are different in location, structure, and function (as the table). In addition, both cells form the interface between the inner and outer environments. Endothelial cells are located “inside” the body, such as the interior of blood vessels, while epithelial cells are often described as covering the “outside” of the body, such as the outer layer of the skin (epidermis, epidermis).

Comparison of endothelia cells and epithelial cells:

Items Endothelial cells Epithelial Cells
Location Endothelial cells form endothelium, a thin layer that covers the inner surface of the blood vessel. Briefly, the cells cling to the blood vessel wall. Therefore, the inner wall of the entire circulatory system is covered by endothelial cells. These cells form the interface between the blood vessel wall and the blood. They close to the inner surface of the heart. They are a thick layer of single cells. The epithelial cells that make up the epithelial tissue cover not only the outer surface of the body, but also the outer surface of all internal organs of the body. For example, the epidermis of the outermost layer of the skin is the epithelial cell. The skin on the surface is thus covered by epithelial cells, which provide a protection for the body. Epithelial cells also cover the surface of internal organs, such as the liver, stomach, intestines, lungs, urethra, bladder, and the like. In other words, epithelial cells cover the surface and internal tissues of the body.
functions Endothelial cells covering the vessel wall regulate blood flow in the blood vessels, which release NO. NO is a vasodilator that promotes blood circulation and helps control blood pressure. Endothelial cells can also secrete a variety of proteins that cause blood disorders, but they also stop bleeding. The inside of the glomerulus contains endothelial cells, which act to filter blood. The epithelial cells that make up the skin protect the subcutaneous tissue from damage, bacterial intrusion, dangerous chemicals, and avoid excessive loss of moisture. When necessary, the skin’s epithelial cells also secrete sweat to regulate body temperature. Epithelial cells covering the pancreas secrete enzymes to promote digestion. In addition, epithelial cells on the surface of the small intestine absorb nutrients from the digested food. Epithelial cells on the surface of the respiratory tract form mucous membranes that secrete mucus to prevent inhaled bacteria and viruses from entering the lungs. Specialized epithelial cells are secreted on organs that are in contact with nerve endings such as skin, nose, tongue, eyes, etc., which recognize sensory stimuli. In summary, the main functions of epithelial cells involve secretion, absorption, and protection.
Features The endothelial cells that make up the endothelial tissue are monolayer structures, and water molecules and oxygen molecules easily pass through the endothelial cells and enter the tissues surrounding the endothelial cells. In addition, endothelial cells lack a packed epithelial morphology, and there are gaps between endothelial cells, which contribute to the passage of liquids and the diffusion of substances. The epithelial cells that make up the epithelial tissue have a variety of structures to protect the body from the external environment. Epithelial cells are tightly bound, similar to bricks, with few gaps between cells.
Intermediate Filaments Some proteins, referred to herein as intermediate filaments, support the cells and form the shape of the cells. Simply speaking, the intermediate filaments provide the cellular structure. Endothelial cells contain vimentin filaments. Keratin filaments provide the structure of epithelial cells.
Surface layer The surface of endothelial cells is a non-thrombogenic, soft surface that does not coagulate during normal blood circulation. Epithelial tissues composed of different types of epithelial cells exhibit irregular papillary projections.

Schematic diagram of endothelial cells (Figure 1) and epithelial cells (Figure 2):

Endothelium is a kind of epithelium. The endothelial cells are distributed on the inner surface of the blood vessels. In the lumen, the endothelial tissues form the interface between the circulatory system or the lymphatic system and other parts of the blood vessels. The structure is as follows:

Figure 1. Schematic diagram of endothelial cells

Figure 2 shows the morphology of epithelial cells. Epithelial cells can be arranged in a single layer of cell structure, or in two layers, or even a multi-layered cell structure. As shown in Figure 2, all glands are composed of epithelial cells. The function of epithelial cells includes secretion, absorption, protection, and transmembrane transport.

Figure 2. Morphology of epithelial cells

Introduction to Transferase

Transferases are a class of enzymes that transfer specific functional groups from one molecule (donor) to another (acceptor). Transferases are implicated in hundreds of different biochemical pathways, and are essential to some of most important processes in lives. Transferases participate in a myriad of cell reactions and are also utilized during translation. Mechanistically, an enzyme catalyzing the following reaction would be considered as a transferase:

Figure 1. Redox reaction.

where X is the donor that is often a coenzyme, and Y is the acceptor. Group would be the functional group that is transferred on account of transferase activity.


Systematic names of transferases are based on the form of “donor:acceptor grouptransferase.” For example, methylamine:L-glutamate N-methyltransferase is the normative name for the transferase methylamine-glutamate N-methyltransferase, where methyltransferase is the EC category, methylamine is the donor, and L-glutamate is the acceptor. Nonetheless, the more frequently used nomenclature for transferases are often in a form of “acceptor grouptransferase” or “donor grouptransferase.” Practically, many molecules are not mentioned by taking advantage of this terminology because of the application of more prevalent common names.


It occurs as early as the 1930s that some of the most important transferases were discovered. Transamination that means the transfer of a NH2 group from an amino acid to a keto acid through an aminotransferase is noticed for the first time in 1930 after the disappearance of glutamic acid appended to pigeon breast muscle, which is subsequently confirmed by the discovery of its reaction mechanism in 1937. This reversible reaction could be also applied to other tissues, which lays the basis for the possibility that their similar transfers act as a main choice of producing amino acids via amino transfer. Later in 1953, enzyme UDP-glucose pyrophosphorylase is revealed to be a transferase, since it is found to be capable of reversibly generating UTP and G1P from UDP-glucose and an organic pyrophosphate. Another historically significant discovery in transferase is illumination of the breakdown mechanism of catecholamine by catechol-O-methyltransferase, which accounts a large part for Julius Axelrod’s 1970 Nobel Prize in Physiology or Medicine.


Up to now, the classification of transferases is still under way for new ones discovered frequently. The category of transferases is described primarily according to the type of biochemical group transferred, and can be divided into ten groups based on the EC Number classification, which comprises more than 450 different unique enzymes and have been assigned a number of EC 2 in the EC numbering system. Hydrogen is not recognized as a functional group when it refers to transferase targets. On the contrary, hydrogen transfer is divided into oxidoreductases in consideration of electron transfer.

EC number Description
EC 2.1 Single carbon transferases under EC 2.1 are enzymes that transfer single-carbon groups, which contain functional groups of hydroxymethyl, methyl, carboxy, carbamoyl, formyl, and amido substituents.
EC 2.2 EC 2.2 includes aldehyde and ketone transferases transferring aldehyde or ketone groups, mainly comprising a variety of transketolases and transaldolases that play important role in pentose phosphate pathway and catalyze the transfer of dihydroxyacetone functional group to glyceraldehyde 3-phosphate.
EC 2.3 Acyl transferases as key aspects of EC 2.3 could transfer acyl groups or acyl groups that are converted into alkyl groups during the process of being transferred. Furthermore, this category also distinguishes amino-acyl from non-amino-acyl groups.
EC 2.4 Enzymes divided into EC 2.4 could transfer glycosyl, hexosyl and pentosyl groups. Glycosyltransferase under the subcategory of EC 2.4 takes participate in the biosynthesis of disaccharides and polysaccharides by transferring monosaccharides to other molecules.
EC 2.5 Currently, EC 2.5 only possesses enzymes that are involved to transferring alkyl or aryl groups, which yet do not include methyl group. This is different from functional groups that are transformed into alkyl groups when transferred.
EC 2.6 EC 2.6 is a group of enzymes that are consistent with transfer of nitrogenous groups, including transaminase, oximinotransferases and other nitrogen group transferring enzymes. Amidinotransferase is previously grouped into EC 2.6, while it has recently been reclassified as a subcategory of EC 2.1.
EC 2.7 EC 2.7 consists of not only enzymes that transfer phosphorus-containing groups, but also nuclotidyl transferases. Subcategory of phosphotransferase is further divided in accordance with the type of group experiencing the transfer. Phosphate acceptors mainly include alcohols, carboxy groups, nitrogenous groups, and phosphate groups. Various kinases are also constituents of this subclass of transferases.
EC 2.8 Sulfur transferases transferring sulfur-containing groups are covered by EC 2.8 and are further subdivided into the subcategories of sulfurtransferases, sulfotransferases, and CoA-transferases, as well as alkylthio groups transferring enzymes. Some specific sulfotransferases could employ PAPS as a sulfate group donor, within which alcohol sulfotransferase has a broad targeting capacity. Therefore, alcohol sulfotransferase is also acknowledged as “steroid sulfokinase,” “hydroxysteroid sulfotransferase,” and “estrogen sulfotransferase.” Decrease in the activity has been concerned with human liver disease.
EC 2.9 Selenium transferases belong to EC 2.9 and only contain two transferases, which therefore is one of the smallest categories of transferase.
EC 2.10 The class of EC 2.10 covers enzymes transferring molybdenum or tungsten-containing groups. However, only one enzyme molybdopterin molybdotransferase, a component of MoCo biosynthesis in Escherichia coli, has been added until 2011.

Applications in Biotechnology

Terminal transferase is one of the few DNA polymerases functioning without an RNA primer, and could label DNA or produce plasmid vectors by adding deoxynucleotides in the form of a template to the downstream end or 3′ end of an existing DNA molecule.

Glutathione transferases with high diversity can be applied by plants to segregate toxic metals from the rest of the cell, which thus can be processed as biosensors to detect contaminants such as herbicides and insecticides. Glutathione transferases could also increase resistance to both biotic and abiotic stress in transgenic plants, and now they are being explored as targets for anti-cancer medications owing to their functionality in drug resistance. Currently the only available commercial source of natural rubber is the Hevea plant.

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Biomarker: Active Pioneer in Medicine Fields

With the development of bioscience, biomarkers are widely used in medicine. Biomarkers are indicators that can judge the occurrence, development and prognosis of diseases. They can be used for the diagnosis and classification of diseases, monitoring the disease development and severity, testing the effect of clinical treatment, predicting an individual’s risk of disease and the screening of high-risk groups. The selection of biomarkers requires strict clinical validation and the feasibility of using biomarkers in specific clinical situations. Nowadays the biomarker development has made the application gradually change from simplification to combination. The combined application of biomarkers and other detection methods is conducive to the early, rapid and accurate diagnosis of diseases, thus providing a basis for clinical treatment.

As can be seen from the definition of biomarkers, biomarkers cover a wide range, and with the progress of detection technology, more specific detection results can be regarded as biomarkers. Here we will introduce 4 biomarkers that are widely used below:

  1. HE4

HE4 is human epididymal protein 4, first found in epithelial cells at the distal end of human epididymis. It consists of two core structures: a 25KDa natural n-terminal glycosylated protein and two whey acidic protein core regions (WAP, consisting of four disulfide bond core regions and eight cysteine residues). The gene encoding HE4 has multiple homologous brothers and also codes for the WAP core protein.

For example, SLPI and Elafin, both of which have protease inhibitory and anti-inflammatory effects, are associated with host resistance to bacterial infection. It was on the basis of “brotherly similarity”, their sibling protein, HE4, was initially identified as having anti-inflammatory and antibacterial properties. Since it is found in epididymal epithelial cells of humans, it is speculated that HE4 may be a protein-inhibiting enzyme involved in reproductive development. With the reveal of follow-up studies, the true nature of HE4 began to emerge. Subsequent studies found HE4 tumor marker expression in tumor cell lines, opening a new window of clinical cognition.

  1. HER2

Currently, the commonly used markers in clinical diagnosis, treatment and monitoring of breast cancer are mainly CA153, CA125, CEA and Her2. HER2, which is considered as a potential marker of breast cancer, has attracted more and more attention. HER2, also known as human epidermal growth factor receptor-2, is a major oncogene responsible for breast cancer. In clinical practice, the determination of whether the expression of HER2 is positive can be used to formulate treatment plans for different types of breast cancer patients.

For the detection of HER2 marker, immunohistochemistry is often used. With the development of science and technology, the serological detection method of HER2 came into being, which has the advantages of convenience, rapidity and feasibility. The detection of HER2 in serum and in tissue can be complemented by each other, so as to more accurately determine the expression state of HER2. It can also be used for monitoring the therapeutic effect of targeted drugs, dynamic follow-up observation and indication of prognosis. Therefore, the detection of serum HER2 level has fully demonstrated its great advantages. As a “potential stock”, it has been recognized by clinicians, bringing significant effects for the treatment of breast cancer.

  1. PCT

PCT (procalcitonin) is a protein that is elevated in plasma during severe bacterial, fungal, and parasitic infections as well as sepsis and multiple organ failure. PCT does not increase with autoimmunity, allergy, or viral infection.

It reflects the level of activation of inflammatory responses throughout the body. Factors that affect PCT levels include the size and type of organ being infected, the type of bacteria, the level of inflammation, and the state of the immune response. In addition, PCT marker can only be detected in a small number of patients 1 to 4 days after major surgery.

  1. ST2

ST2 marker is a myocardial protein produced by cardiac myocytes under biomechanical stress. It is a soluble protein expressed in response to heart disease or injury, and reflects ventricular remodeling and cardiac fibrosis related to heart failure. Studies have shown that the concentration of ST2 is related to the severity of heart failure, left ventricular ejection fraction, brain natriuretic peptide (BNP), type B brain natriuretic peptide precursor (NT-proBNP) and creatinine clearance rate, but not age, previous history of heart failure, history of atrial fibrillation and body mass index. And BNP, NT-proBNP is often affected by these factors, therefore, ST2 combined with them determination can improve the accuracy of assessing the prognosis of heart failure. Meanwhile, recent studies have shown that ST2/ IL-33 signaling pathway plays an important role in the processes of asthma, autoimmune diseases, anti-atherosclerosis, anti-myocardial fibrosis and myocardial cell hypertrophy.

Biomarkers are powerful tools for ivd assay. With the progress of detection technology, the introduction of more ideal statistical analysis methods or algorithms, the use of larger and more comprehensive case samples and the deepening of people’s understanding of the details of life activities, more and more ideal biomarkers will be found and applied in clinical practice.

Wholesale Supply Chains in Business

Most merchants will testify to the fact that supply chains are often the most important factor in delivering products to their destination. Merchants that are capable of understanding this will reap all the benefits of an expanding market. If you can secure your own marketing model, then the supply chain will ensure that you do not run out of products to put out onto the market. Drop shipping is one of those areas where the supply chain will play a crucial part in the level of success that the merchant can expect.

Solutions for merchants

Some merchants have decided to buy their products wholesale from China in order to ensure that they have a constant stream of items to put on the market. China is the workshop of the world. They seem to have an inescapable capability to produce everything and anything. That means that the merchant simply has to run down the list of items that are on sale and then make an offer. In most cases this will translate into instant profits. Some people are convincingly argued that the presence of different marketing forums means that the supply chains can be changed if there are bottlenecks.

That is certainly true if you are dealing with the Chinese market. Here the merchant can lay down some specifications which are conditions for the business relationship. If these conditions are not met then the merchant is well within their rights to find alternative sources of products. That can help to keep the merchant in line as well because they have to monitor supply chains. For example you will need to watch the journey of a wholesale Tablet from the time an order is made to the time that delivery is completed. The merchant will be getting regular updates on the progress of the order so that they can clear up any difficulties.

What makes supply chains difficult?

Often stock control or the lack of it is the problem. Some manufacturers are not very clear about their capacity. Therefore they will accept orders that cannot be easily fulfilled. This is very frustrating for the merchant because they have to turn round and appease an irate customer. The best solution is to limit orders to the capacity that the supplier has. In order for this to happen, the supplier has to be candid about the limitations of the chain. They should be able to turn down orders in advance if the capacity is just not there.

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Import Express, a B2B based wholesale website. Since 2005, Import express has played a critical role in helping more retailers grow faster around the world. As an experienced end-to-end wholesale solution company, Import-express provides professional wholesale and drop ship service. The website continue to provide high-quality wholesale business service that empowers retailers to do more business all over the world.

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