Cloning: Antibody Cells CD34, CD45, CD73, CD90 and CD105

Human cloning is a widely controversial topic to people who do not fully understand the science behind cloning as most people have an ethical issue with cloning a human. While it is called human cloning it is not the process of completely cloning a full body human. Cloning for medical purposes includes being able to clone fully functional stem cells that are used to build, maintain and repair the human body throughout our entire lives. It is even possible for these cloned stem cells to be used to create whole organs for people who are in need. Normally there is a few issues that would arise when transplanting stem cells into another person because they can be seen as foreign entities by the human body. Human cloning provides the means to create exact copies of people's stem cells essentially removing the issues that would arise when the body detects the stem cells as foreign. Cloning also could help with the discovery and modeling of diseases from animals that have been cloned for the purpose of disease discovery. The process of human cloning is performed by the use of somatic cell nuclear transfer(SCNT). This is the same process that was used to create Dolly the sheep. SCNT begins when an egg is taken from a female donor and its nucleus is removed leaving a enucleated egg. A cell is then taken from the person who is being cloned and fused with the enucleated egg through use of electricity. These are only two ways that human cloning would be beneficial to the the medical field there are a plethora of cells that human cloning can help be beneficial with. A few major cells that will be discussed during this research report are the antibody cells CD34, CD45, CD73, CD90 and CD105.

CD34 is a type 1 transmembrane glyco phospho protein expressed by hematopoietic stem/progenitor cells, vascular endothelium and some fibroblasts. CD34 expression has been used as the hallmark used to identify hematopoietic stem cells for quite a few years. CD34+ hematopoietic stem cells have been used for years due their ability to expand and differentiate into all the lymphohematopoietic lineages upon cytokine or growth factor factor simulation and lose CD34 expression upon differentiation. There has been recent laboratory studies performed that show there is a conflict with the convention of the CD34 antibody. CD34's extracellular domain has been shown to be homologous to that of CD43. CD43 is a protein involved in cell-cell adhesion, and CD34 has been shown to function as a negative regulator of cell adhesion. CD34 was found to associate with CrkL, but not Crkll, and is a substrate for PKC, and the activation of PKC is coupled with the surface expression of CD34.

The anti-CD45 cell is a type 1 transmembrane that consists of two intracellular phosphatase domains, a transmembrane domain and an extracellular domain. The intracellular domain of this cell consists of two domains. Only one of these two domains has intrinsic kinase activity. However, both of these domains are required for appropriate phosphate activity. The extracellular domain of CD45 contains three membrane proximal fibronectin type II repeats, a cysteine rich region and the variable N-terminal region. CD45 has many functions such as in T cells, CD45 dephosphorylates the tyrosine kinase Lck a residue Y505, as a part of TCR activation signaling cascade. This activation signaling ultimately this leads to increased cytokine production and proliferation of T cells. CD45 was originally known as the common leukocyte antigen. .CD45 is a receptor linked protein tyrosine phosphatase present in cells of the hematopoietic lineage except erythrocytes and plasma cells. The basis of this information was found in a study published to the Journal of Experimental Medicine.

A study in the Journal of Cell Biology explains the functions and makeup of the cell CD73 is otherwise known as ecto-5'-nucleotidase, a glycosyl-phosphatidylinositol-linked 70-kD molecule expressed on different cell times. These cell types include vascular endothelial cells(EC). As well as certain subtypes of lymphocytes cells. There is evidence showing that CD73 plays a role in several immunological phenomena, such as lymphocyte activation, proliferation, and adhesion to endothelium, but the physiological role of CD73 is less clear in other cell types. From studies of the structure and function of CD73 on lymphocytes and EC, CD73 molecules on lymphocytes have shown to shed from the cell surface consequently of triggering with an antiCD73 mAb, mimicking ligand binding. The triggering of endothelial CD73 has been shown to not have any effect on its expression. The Lymphocyte CD73 is susceptible to phosphatidylinositol, whereas CD73 on EC only a small portion could actually be removed by this enzyme. This study also showed that CD73 on EC is unable to deliver a tyrosine phosphorylation inducing a signal upon the triggering of mAb. Whereas it was seen that CD73 on lymphocyte can indeed induce tyrosine phosphorylation. Despite these two differences they are essentially identical structurally to each other when studied at the protein,mRNA, and cDNA level.

The next antibody cell discussed is CD90 which is also known as Thy-1 according to a study in the Journal of Immunology. CD90 is a small GPI-anchored protein that is abundant particularly on the surface of mouse thymocytes and peripheral T-cells. The proliferation of t-cells and synthesis of cytokine in response to Thy-1 cross-linked by specific mAb suggests a role for Thy-1 in mouse T lymphocyte activation. Cross-linking of Thy-1 in the context of strong costimulatory signaling through CD28, results in an activation signal that can partially substitute for TCR signaling during mouse T-cell activation. Thy-1 has been conserved through the entirety of evolution thus far suggesting that it plays an important function. The core protein of Thy-1 in rodents consists of 111 or 112 aa, and is N-glycosylated at three sites. While the human Thy-1 contains only two glycosylation sites.Thy-1 is a heavily glycosylated membrane protein with a carbohydrate content of up to 30%.Thy-1 is known to be present on brain cells and fibroblasts of all species studied thus far. In a mouse Thy-1 was also found on a variety of other cells including thymocytes, peripheral T-cells, myoblasts, epidermal cells, and keratinocytes. In humans, Thy-1 is also expressed by endothelial cells, smooth muscle cells, a subset of CD34+ bone marrow cells, and umbilical cord blood.

All of these cells were used in a study involving distinct features of rabbit and human adipose-derived mesenchymal stem cells with implications for biotechnology and translational research. The aim of this study was to comparatively characterize rabbit ASCs(rASCs) and hASCs(human adipose-derived mesenchymal stem cells) to further uses in biotechnology and translation studies. The study used rabbits for their research as they are widely used as experimental models for both human and veterinary medicine due to their ease to work with. The rabbits share many similarities with human making them useful for multiple applications in biotechnology and translational medicine from basic research to preclinical studies, such as fertilization in vitro, embryonic development and organogenesis, immunology, toxicology, neurophysiology, ophthalmology, and cardiology. The study performed flow cytometry in second passage rASCs and hASCs for detection of surface antigenic markers CD34, CD45, CD73, CD90, and CD105. White blood cell fractions were used as positive controls for CD34 and CD45. Negative control staining was performed by using fluorophore-conjugated mouse IgG isotype antibodies. The flow cytometry analysis showed that rASCs and hASCs were absent of hematopoietic markers CD34 and CD45. The analysis also showed that rASCs and hASCs were positive to CD105, CD73, and CD90. Expression of CD73 and CD90 were seen to be significantly lower in rabbit cells than in comparison to human cells. The proliferative profile showed that rASCs had a higher threefold potential to form fibroblastic colonies in vitro compared to hASCs. CFU assay showed rASCs were able to generate colonies with five cells or more, while hASCs struggles to generate colonies with only five cells. The colonie sizes of the rabbits were also seen to be significantly higher in rabbits compared to humans. rASCs were found to have a greater proliferative potential in vitro than that of hASCs as rASCs maintain their nuclear stability better in vitro. rASCs and hASCs were also observed to have low frequency of errors in vivo.

The discovery that rASCs have higher proliferation profiles in vitro can be a great thing to the process of cloning as they are also great at achieving a high number of cells in a short amount of time. Leaving the rASCs to be greatly desired in cell-based therapy studies. Such as preclinical studies where MSC transplantation in tissue engineering would often require millions to billions of cells.The rASCs would be able to achieve these numbers at the greatest pace we have seen thus far. While this might be a breakthrough for cell-based therapy biotechnology studies have suggested that a faster proliferation could be potentially detrimental to reprogramming a cell(). So the question we must answer now is if rASCs should be left purly to cell-based therapy studies where they will seemingly thrive or if they have their place in biotechnology studies. The question we must be asking now is if higher proliferation rates is so detrimental is there any way the rASCs proliferation rate could be lower to a seemingly safer rate making it a more effective means of reprogramming DNA. If we were able to find a way to do this properly the rASC could be used for countless amounts of studies and clinical trials furthering our knowledge of DNA and diseases.

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