Stem cell – 3997 words – College Essay Example
Stem cell – 3997 words – College Essay Example

Stem cell – 3997 words – College Essay Example

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  • Pages: 11 (2862 words)
  • Published: November 8, 2018
  • Type: Case Study
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Stem cell research has become a topic of media attention, public debate, and government involvement. These cells have the potential to benefit a broader range of patients in need of transplants and offer new treatments for conditions such as diabetes, Parkinson's disease, Huntington's disease, heart disease, stroke, and spinal cord injury. However, controversy arises due to the use of a specific type of stem cell obtained from early embryos that can generate different cell types for therapeutic purposes. Additionally, cloning technology may be used to customize stem cells for individual patients. While some individuals are morally opposed or uneasy about this research, others strongly advocate for its acceptance. So what exactly are stem cells and how can they be utilized? Although there are various types of stem cells with unique characteristics that differentiate them from other cells, the human bod

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y contains many specialized or differentiated cell types that serve specific functions. Some cells like nerve cells have long lifespans without dividing while others rely on cell division for replacement and have shorter lifespans. Symmetrical division refers to when cells divide in a way where their daughter cells are identical to the parent in both type and properties.In addition, these specialized cells possess fixed characteristics and destinies, indicating that once a liver cell is formed, it remains a liver cell permanently. Stem cells undergo "asymmetric" divisions wherein they renew themselves and produce differentiated cells that cannot revert back to their original cell type. While stem cells can multiply and generate more stem cells, adult stem cells primarily function within their specific tissue by dividing at an appropriate rate for self-renewal and producing enough differentiated cells for

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replacement purposes. However, in cases of injury or disease, the natural regeneration process tends to be too slow in tissues like the nervous system and pancreas. This raises inquiries about how we can utilize stem cells for therapeutic purposes. Medical practices have employed organ transplants to address ailments like cataracts or heart and kidney diseases. Challenges arise from immune rejection and limited availability of organ donors; thus, utilizing tissue from one part of an individual's body to repair another part offers a potential solution. Currently, this approach is seldom used except when substituting damaged heart valves with leg vein valves. An alternative option involves using stem cells capable of developing into specific tissues instead of relying on whole organs or tissues from donors. Bone marrow transplants involving grafts of stem cells with regenerative abilities across various blood cell types are already being implemented.Similarly, when complete structures cannot be transplanted, other types of stem cells can be utilized for replacing damaged tissues in the nervous system. The suggested technique involves extracting and multiplying stem cells from a specific tissue outside of the body, which can then be used for tissue replacement. This method is currently used to some extent in repairing burn victims' skin by growing a small sample to cover a larger area than the original biopsy. However, there are challenges associated with using adult stem cells such as their limited availability and certain tissues lacking them. Our understanding of the conditions under which adult stem cells can multiply outside of the body is often insufficient and these conditions may not exist if they rarely divide within the body. Additionally, adult stem cells themselves are

rare and in individuals with diseases, normal stem cells may be even rarer or completely absent. Therefore, finding a suitable donor is necessary as seen in bone marrow transplants; however, it is difficult to find a tissue match with an identical twin being the most ideal source – although they are not easily accessible to most people. Nevertheless, it is important to note that the use of adult stem cells still shows promise. There may be ways to enhance their growth and function either externally or internally. Recent research has revealed that some types of adult stem cells possess more capabilities than previously believed.
The discovery that stem cells can transform into different cell types, such as blood stem cells becoming nerve cells, opens up possibilities for patient-specific stem cell therapy. This means that stem cells from one part of the body can be used to repair damage in another part. For example, blood stem cells could be converted into nerve stem cells and then differentiated into specific nerves for treating conditions like Parkinson's disease. However, there are considerations regarding the availability and accessibility of adult stem cells before attempting therapy.

Blood stem cells are rare, with only one in ten million found in blood samples. Obtaining them from bone marrow still requires a risky and uncomfortable biopsy procedure. Additionally, it is uncertain whether umbilical cord blood has the potential to generate other types of cells beyond those found in the blood system.

Another challenge is isolating valuable islet-producing stem cells in the pancreas believed to be located in pancreatic ducts. Furthermore, achieving laboratory expansion of neural stem cells within the nervous system has not yet been accomplished.

Despite

these challenges related to scarcity and access, recent evidence has shown greater flexibility among certain types of adult stem cells, which paves the way for patient-specific therapies targeting hard-to-reach areas within the brain and spinal cord.However, it is important to consider limitations in terms of availability and accessibility before proceeding with any therapeutic intervention involving these valuable cellular resources. Concerns arise regarding the grafting of nervous system cells between individuals due to potential rejection and the presence of diseases like Creutzfeldt-Jakob Disease.

The location and existence of stem cells in many adult cell types remain unknown. Stem cells capable of replacing lung lining cells necessary for conditions such as Cystic Fibrosis, emphysema, or inhalation burns have not yet been identified. These specific cells can be found in embryos and fetuses where they divide frequently and are easier to cultivate outside the body.

Many of these cells possess multipotent capabilities, meaning they have the ability to develop into different specialized cell types. However, while daughter cells resulting from asymmetric divisions of these "fetal stem cells" do not necessarily undergo exact self-renewal, their progression limits their ability to produce certain types of cells.

The most potent type of stem cell is Embryonic Stem Cells (ESCs), which originate from a blastocyst – a cluster formed after five days of human development or three days in mice. At this stage, approximately one hundred cells exist containing two distinct cell types: outer ones that contribute to the placenta and inner ones that become the embryo.While most inner cells in the embryo only contribute to its support system that is discarded at birth, each cell has the potential for development. At the blastocyst stage,

it is impossible to identify a specific cell that will contribute to the newborn individual. The survival and development of both types of cells are dependent on each other. If the inner cells are removed from the outer cells, an embryo cannot develop. However, these inner cells can be cultivated in a lab and become Embryonic Stem (ES) cells. ES cells have remarkable properties, such as their ability to grow indefinitely in large quantities. Unlike other cell lines with permanent growth due to gene mutations or transformation genes from viruses or tumors, ES cells are normal cells. Additionally, under appropriate conditions, they can differentiate into any type of body cell. Studies have shown that injecting ES cells into blastocysts of laboratory mice results in integration and contributions to all tissue types in the resulting animal. These chimeric mice have a normal lifespan and do not display higher rates of tumors or diseases compared to regular mice. Furthermore, ES cells can also generate various cell types when cultured.In a laboratory setting, techniques have been established to guide the differentiation of human embryonic stem cells into specific cell types like nerve cells, muscle cells, blood vessel-forming cells, and pancreatic islet cells. These artificially generated cells have been successfully transplanted into animals, leading to partial improvements in diseases such as Parkinson's Disease, multiple sclerosis, and diabetes.

The potential for these stem cell lines to effectively treat various diseases through cell-based therapies is significant. However, immune rejection poses a major challenge due to the limited number of available cell lines. To address this issue, it is necessary to create a large bank of tissue-typed cell lines consisting of hundreds or

even thousands. This would ensure closer matches between patients and therapy types.

Even with a large bank of tissue-typed cell lines, transplantation still requires the use of immunosuppressive drugs to prevent rejection. However, these drugs can have severe consequences such as an increased risk of infection and potential tumor development. Therefore, careful evaluation of the potential benefits and drawbacks is crucial before proceeding with therapy.

Different graft types may require different levels of tissue matching. For instance, bone marrow grafts are particularly challenging as they carry risks of both graft rejection by the host and host rejection of the graft itself.In cases where the patient's immune system destroys insulin-producing beta-cells in the pancreas' islets associated with diabetes management, close tissue matching may also be necessary for other cell-based therapies. Obtaining human embryonic stem cells may require spare embryos from in vitro fertilization programs, although there are currently more discarded embryos than needed to establish a significant number of embryonic stem cell lines. Initial studies show a high success rate in deriving human embryonic stem cells from normal blastocysts, and further improvements can be made through experience. Ideally, it would be best to isolate embryonic stem cells from the patients themselves during early stages of embryo development when the appropriate cell type exists. Alternatively, suitable stem cells could potentially be obtained by reversing the differentiation process from an adult cell. The text explores how cloning techniques used on animals like Dolly the sheep, mice, cows, goats, and pigs have been used to reprogram adult cells. It suggests that factors capable of reprogramming adult cells into embryo cells may come from early embryos or germ cells found in unfertilized

eggs in females and sperm in males. The article also discusses how nuclear transfer technology allows for cloning by replacing the nucleus of an oocyte with that of an adult donor cell.There are concerns about using this technology to obtain human Embryonic Stem cells and whether it can be done using the patient's own cells to prevent immune-rejection issues. The success of this technology in humans is uncertain, as results have varied among different species. A company in the US claimed to have cloned early human embryos but failed to convince experts with their evidence. The article emphasizes the need for further research in this field, without specifying how these outcomes can be achieved.

One method involves obtaining adult cells through biopsy from patients and transferring them into oocytes using nuclear transfer. Afterward, the reprogrammed adult cell nucleus would develop into an early embryo, which would be cultured outside the body until it reaches the blastocyst stage. The inner cells of the blastocyst would then be isolated and used to derive Embryonic Stem (ES) cells that have the same genetic makeup as the patient.

The techniques learned from ES cells in mice could potentially be used to treat conditions such as Parkinson's disease, heart disease, or spinal cord injury. Recent studies suggest that human ES cells have the ability to differentiate along specific pathways. In cases of genetic diseases like cystic fibrosis or muscular dystrophy, it might be possible to correct any genetic defects in stem cells before implantation – a feat already accomplished with mouse ES cells.Once individual-specific ES cells are created, they can address other issues within a person's body. Although it remains unclear which

source is ideal for human biopsies, certain cell types have proven effective in other species – for example using mice tail tips as a skin biopsy has shown promise. Further research is necessary regarding this subject matter.

Accessible human cell types may serve as effective nuclear donor cells. Some individuals who believe that life begins at fertilization may find it unacceptable to use leftover embryos from in vitro fertilization (IVF) programs for creating embryonic stem cell lines. In contrast, the technique of cell nuclear replacement uses unfertilized eggs, which do not raise the same ethical concerns. These eggs have their genetic material replaced with that of an adult cell nucleus, making them an extension of the adult donor and a potential universal organ for donation. This personalized approach could also address religious objections to transplants between individuals.

However, there are those who oppose cloning altogether, even for beneficial therapeutic purposes. These concerns often arise from fears of unsafe reproductive cloning, which has led to issues or death in many cloned animals. Nevertheless, just because a technique can be used for one purpose does not guarantee negative consequences.Legislation should be enacted to prohibit reproductive cloning, as it is already illegal in the UK. When using nuclear transfer to reprogram adult cells, careful consideration must be given to the source of unfertilized eggs and suitable donor cells. Concerns arise regarding the availability of unfertilized eggs for large-scale patient-specific stem cell therapy, especially if only leftover eggs from In Vitro Fertilization programs are used. However, it may be possible to reprogram adult cells by utilizing a small portion of egg cytoplasm and identifying necessary factors within it. If research confirms

this, the future need for eggs could be eliminated. There are alternative sources of unfertilized eggs beyond IVF programs. Techniques are being developed to extract undeveloped oocytes from primordial follicles in mice and farm animals' ovaries. These follicles can be cultured under conditions that support growth at different stages of development. Although ethical concerns arise, oocytes obtained from aborted fetuses' ovaries could potentially be utilized. Additionally, women might be more willing to donate unfertilized eggs if they knew their loved ones could benefit from stem cell therapy. Adult donor cell types like skin biopsies do not pose sourcing or rarity issues; some other cell types requiring only a small number of cells for the nuclear transfer step may even offer better advantages.Skin stem cells are well-known for their ability to divide extensively, which makes them potential candidates for nucleus donation. If we can develop simple and effective methods to isolate blood stem cells, they may have even greater advantages. Embryonic stem cells can be easily purified, grow well in culture, and have a limitless lifespan. Moreover, the technique of cell-nuclear replacement has shown promising results in rejuvenating adult cell nuclei. The value of embryonic stem cells lies in their capacity to differentiate into any type of cell in the body, making them valuable for treating various diseases. Additionally, specific cell types can already be selected from differentiating mouse embryonic stem cells in a controlled manner. These selection techniques have been tested in animal models of corresponding human diseases or injuries across multiple studies. Notably recent research includes the development of a stem cell type capable of generating all cell types found within blood vessels, providing

potential treatment options for chronic conditions like coronary heart disease. A Japanese research team has discovered a new factor that allows them to obtain pure populations of neurons associated with Parkinson's disease. In the United States, researchers have successfully derived insulin-producing cells from embryonic stem cells—a feat yet to be accomplished with adult stem cells.The establishment of patient-specific stem cell therapy methods and the necessity of embryo research are questions that remain unanswered. Studies in mice have demonstrated that nuclear transfer technology can be utilized to derive Embryonic Stem (ES) cell lines from biopsy samples, which possess expected properties and can differentiate into various cell types. Although ES cells can also be derived from human blastocysts obtained through In Vitro Fertilization, it is uncertain whether nuclear transfer technology can reprogram adult cells to generate suitable blastocyst stage embryos. Recent research with human ES cells has shown promising results in obtaining different cell types in the laboratory; however, further investigation is necessary due to variations between mouse and human ES cells before their potential for disease treatment becomes a significant challenge. Initially, animal studies can be conducted, but eventually, human trials must be undertaken while implementing quality control methods to ensure safety and reliability of the utilized cells. The potential demonstrated by mouse ES cells needs to be replicated in human ES cells as well since they have the natural ability to generate any type of cell within the body, making them an ideal source for cell-based therapies.Currently, the creation of patient-specific Embryonic Stem cells involves using many unfertilized eggs. Another option is to convert adult cells into Embryonic Stem cell equivalents by using egg cytoplasm

and nuclear transfer, which is the only regulated reprogramming technique known at present. By understanding these mechanisms, it may eventually be possible to transform adult cells into Embryonic Stem cells without the need for human eggs. Therefore, research on adult stem cells is crucial as both adult and embryonic stem cells hold promise in treating various illnesses. It would be illogical to stop researching either type in favor of the other, especially considering our limited knowledge of both categories.

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