Free Essay Sample on Extracellular Vesicles

State the specific issue or problem that you selected [one paragraph]

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The key issue that the following paper seeks to discuss is the cell biology of extracellular vesicles. The extracellular vesicles are identified for the role that it plays in providing intercellular communication in various cellular processes such as the coagulation and immune responses. The scientific community has become much interested in extracellular vesicles the because of the role that they play in the intercellular communication; it is long known that cells release vesicles to an extracellular environment at the time of apoptosis; although, it has recently been identified that, the healthy cells produce vesicles to the extracellular environment. Various names have been used by the scientists to refer to the vesicles that are produced by the healthy cells, among them include shedding microvesicles, microparticles, and exosomes among many others. To make the field organized, researchers are encouraged to use only one generic term for all secreted vesicles, extracellular vesicles (EVs) is a preferred term chosen. The extracellular vesicles refer to the heterogeneous group of cell-derived membranous made u of microvesicles and exosomes, that rise from the endosomal system or the ones shed from the pathological and physiological processes (Rosa-Fernandes, 2018).

Describe why this issue is important to the field of study

This study on extracellular vesicles is significant as it will focus on the cell function and structure, together with the major concepts by giving a detailed understanding of the tissues as well as the cell composition. Presently extracellular vesicles are being viewed as an added mechanism for intercellular communication, letting the cells to exchange, lipids, proteins and the genetic components. The issue is significant to the field of study since the knowledge of the cellular process that regulates the vesicle biology is important to shed light on the pathological and physiological functions of these vesicles together with the clinical applications including their use pertaining their use or/and analysis.

The study will offer an in-depth analysis and understanding of the previous research on extracellular vesicles together with the present research and concepts. As it is known, extracellular vesicles are heterogeneous; in that case, a consensus terminology for each subtype is yet to be developed (Yuana, Sturk & Nieuwland, 2018).

The issue discussed in this field of study makes us understand the function of the EVs as follows:

They function for the cell survival: Once after being administered with chemotherapeutic drugs during treatment, the cells tumor secrets vesicles that that has the respective drugs, exosomes play its role to reduce the concentration of the intercellular.

As angiogenesis: The EVs have both the anti and pro-angiogenic properties. Angiogenesis entails the formation and development of the new blood vessels to facilitate the tissues and organs with nutrients and oxygen, and remove the metabolic waste simultaneously.

Intercellular communication functionality: the EV can transmit the biomolecules to recipient cells, like ligands, adhesion reception genetic information and cytokines; hence they can transform the function and composition of the recipient cells.

Enhancing the inflammation and autoimmune responses: The leukocytic characteristics of EVs originate from the RA patient's Synovial fluid.

Functions in waste management: Vesicles they contain laid off intercellular components hence functioning as cellular waste discarding packages by their extrusion from the cells.

Give a brief outline of previous research findings that contributed to our current understanding of this issue. Be sure to explain how they contributed to the problem [1-2 pages]

In the previous decades, there has been increasing attention regarding the secreted extracellular vesicles (EVs), particularly in the depiction of their molecular cargo as well as their role as messengers in both in prokaryotes and eukaryotes.

Extracellular vesicles have been widely classified into other basics like microvesicles, apoptotic bodies, and exosomes following the cellular origin. The illustration below indicates further.

Exosomes Microvesicles Apoptotic Bodies

Origin Endocytic pathway Plasma membrane Plasma membrane

Size 30-110nm 50 to 1000nm 600 to 2000nm

Function Facilitate intercellular communication Facilitate intercellular communication Initiate phagocytosis

Markers CD63, CD81, CD9 (Tetraspanins)

Tsg101 and Alix

Selectins, CD40, and Integrins Phosphatidylserine and Annex V

Contents Nucleic acids and proteins such as miRNA and mRNA Nucleic acids and proteins such as miRNA and mRNA Cell organelles and nuclear fractions

Both microvesicles and exosomes are produced by healthy cells. However, they are different on various basics. By the above illustrations, exosomes acquire the size of a non-meter vesicle which has an endocytic origin. It forms a budding on the inward side of the limiting membrane of MVEs (Multivesicular endosomes). It is therefore notable that the size of Exosomes is the same as that of intraluminal vesicles. In measurements using nanometer, the readings are between 40 and 120nm.Exosomes have a high enrichment in endosome-associated proteins because of their endocytic origin. These proteins include SNAREs, flotillin, Annexins and Rab GTPases. However various proteins are later used as markers of exosomes. One member of membrane proteins is the Tetraspanins which are significant in clustering into micro subjects or domains at the plasma membrane. Most of these proteins are abundant in exosomes having it that they all also consider being markers. Due to their complexity, Multivesicular bud starting from the surface of the cell. The size may then tend to increase between or from 50-1000nm. It is good to note that much information is not available the availability of proteins in MVs. The primary markers of protein are integrin, CD40, and selectins.

(http://www.abcam.com/primary-antibodies/extracellular-vesicles-an-introduction)

Extracellular vesicles represent a potential source for biomarker discovery

One finding has stated that extracellular vesicles circulate in fluids like urine and blood among other fluids found in the body. A notable similarity is that extracellular vesicles resemble the parental cell. Therefore, its circulation has raised reasonable questions being a source of biomarkers. The original composition of EVs is the exosomes and MVs. In urine and blood, extracellular vesicles indicate the reduction of a body fluid composition that is complex including various orders of magnitude. When EVs are isolated the result id a complex enrichment of molecules signified by low abundance. This approach may then lead to being a fundamental attribute of pathophysiology. miRNAs have signatures that indicate a biomarker family that has been identified with typical characteristics of developmental origin and tumor type. There are a close association and linkage between EVs and miRNAs, and therefore a keen search of appropriate miRNA signatures is done by analyzing the circulation of tumor-derived Extracellular Vesicles. Using the flow cytometry, it is possible to profile multiplex cellular miRNA. This process is done using the Firefly Technology.

Extracellular Vesicles and Cellular Homeostasis

Organismal homeostasis and Cellular Integrity are maintained by the involvement of Extracellular vesicles in homeostasis. Besides, the association also becomes a fundamental concept in dealing with stress conditions. The various pathophysiological processes where EVs are involved have received positive reviews, but the same will not be included here. Multiple vesicles are categorized by their release pathway or biogenesis using EV as the defining factor. Some of these breakdowns or categories include ectosomes, exosomes, microvesicles, incomes and apoptotic blebs as outlined by the ISEV (International Society of Extracellular Vesicles).

Each Extracellular composition carries various molecular notations. However, the EV cargo is not random. The Extracellular vesicles incorporate signals using lipids, proteins sugars and nucleic acids transmitted by the membrane vesicles that are nano-sized. A specific package of molecules decides the kind of extracellular signal to be received by the recipient cells as a signal. The protein composition of Extracellular vesicles entails disease form cells and includes specific features to the EV that influence their initial biological processes (Mellisho et al., 2018).

Experiment 1: MVB and EVs Identification

Based on this experiment, it entailed the culturing of embryos into categories, selection of best blastocysts on the seventh day and grouping in quantity of tens in the media that had suffered depletion up to the ninth developmental day. The blastocysts on day seven and those expanded types on a ninth day are as presented in Table 1 and S2 Fig. No statistical variations in the rates of the blastocyst, size of the embryo and rate of expansion was noted on the seventh day among the two groupings (PA and the IVF). Regardless of this, during the ninth day that marked the culturing, expansion of blastocyst got from the IVF had notable high averages in term of diameter in comparison to those got from the PA as shown in Table 1.

The analysis of TEM that touches on the secreted EVs from blastocysts while in culture period from seventh to ninth proved that the availability of a minimum of the EVs two populations: EXs and MVs that are characterized by the dense look and shape that is rounded fixed through a by lipid layer and the diameter is averaging 30nm to 385nm as presented in Figure 1A and IB.

TEM enabled for clarity in the localization of the various organelles with some including mitochondria, MVB, lysosomes, Golgi apparatus, and autophagosome present in blastomeres (Figure 2 covers on this). An identified and conspicuous availability of the bigger droplets of lipids in the IVF and PA got from blastocysts were noted. Similarly, several microvilli had their projection in the space connecting the blastomeres. However, they were looked somehow short and partly devel (opened within the IVF embryos in comparison to the PA embryos (van Niel et al., 2018).

Figure 2: Microphotograph representatives depicting the PA and IVF ultra-structures got from blastocysts

Analysis of the Electron Microscopy Transmission (Experiment 1)

Electron microscopy transmission was applied in the identification of the EVs morphology and also in the identification of the MVB got from the intracellular based compartments as the exosomes precursors. The pellets of the EVs in suspension after that had their deposition done on former carbon type of coated copper based grids for the complete mounting organization and its subjection done towards the analysis of TEM as already described earlier. Four types of grids for the analysis of TEM of the vesicles that had been put into isolation were computed for every category of the embryo; that is the PA and the IVF (Mellisho et al., 2018). After this, it followed with the washing of the grids and their fixation in a one percent glutaraldehyde through a 0.1 M PBS and further contrasted through the uranyl-oxalate type of solution of pH concentration of 7.0 for five minutes. The same was also done in the methyl cellulose-UA through the ice for ten minutes. A summation of sixty-five fields and images underwent processing through the use of Image J 1.47t type of software (Rosa-Fernandes, 2018).

On a ninth day, there was expansion and hatching of the blastocysts that were initially fixed. Next was their cleaning with PBS for five minutes two times and also had to be fixed...