Artificial Organs

http://www.creatingpositivelives.co.uk/

Regenerative medicine is a rapidly growing field that offers endless possibilities for doctors and patients alike. While there are still many discoveries to be made and technology to be developed, there have already been incredible advances. For example, doctors have created an extracellular matrix, which is a powder made from pig bladders. It is a mix of proteins and connective tissue, which means it can regenerate tissue by mobilizing the cells that maintain and repair injuries in the body. This has already been shown to help regenerate a part of a man's finger, and scientists believe that, if studied further, they can create new limbs and skin for amputees and burn victims respectively.

Sangeeta Bhatia has had a huge role in advancing regenerative medicine. She specificially studied manufacturing a liver by taking liver cells out of the body - the problem was these cells quickly died once removed. Bhatia hypothesized that the arrangement of these cells is crucial to their survival, and ultimately their function. Similar to how the complex networks of a computer chip are built through light, Bhatia used a chemical reaction with light to manipulate the placement of liver cells outside of the body. Although it took over a year, Bhatia eventually had the proper formation. In addition, these cells maintained life for an unprecedented six weeks. With enough time and support, enough networks of tissue can be built to construct an entire functioning liver. Procedures to build artificial bladder, skin, and even valves of a heart have been successful as well.

http://eecsfacweb.mit.edu/

There are many benefits for artificial organs, which can replace, restore or enhance organ function in a sick individual. First, being able to construct an organ decreases the need for transplant surgeries, which are risky because the organs have a short amount of time to be delivered and not every organ is a match for a recipient. With artificial organs, however, we do not need to worry about rushing the procedure to keep the organ alive, and if an organ is made from the recipient's cells, then it would be a guaranteed match. Another benefit is that these artificial organs can be made as subjects for testing the toxicity of new drugs, thus reducing the need for animal testing.

However, there are also reasons to be cautious when dealing with artificial organs. There is a possibility that undiscovered diseases or defects in the cells used to build artificial organs could lead to fatal consequences if left unchecked. Also, similar to the stem cell debate, there is a question of whether or not it is ethical to create the systems of life in a laboratory. Some believe that only God has the ability to create life, and humans should not have this capability.

Stem Cells

http://www.amyshah.com/

Embryonic Stem Cells (ES) - Cells taken from unused human embryos at IVF (in-vitro fertilization clinics) that can become any type of cell. However, using these cells destroys the human embryo.


Induced Pluripotent Stem Cells (iPS) - Cells taken from the skin that are reverted back into embryonic cells by switching certain genes on and off (there are 4 out of 20,000 that can help reprogram cells). These cells are implanted in a virus and sent back into the body. This treatment may carry a high risk of cancer.


Adult/Somatic Stem Cells - Undifferentiated cells taken from certains areas of the body that can be manipulated to become differentiated like surrounding tissue. There is thought to be specific areas of tissues and organs that are "stem cell niches," rich in this type of stem cell. There is a phenomenon called transdifferentiation, in which these stem cells can create cells that perform a different function than what is expected.

http://stemcells.nih.gov/

How do scientists get stem cells to specialize in a lab?


Scientists remove the outer layer of a blastocyst and put the inner layer in a petri dish. Only a few survive, but the ones that do can create colonies. These colonies go through self-renewal: they are immortal and can continue to grow indefinitely. At some point, these cells differentiate: they begin to become ectoderm/mesoderm/endoderm cells. To control this differentiation, we add growth factors (Retinoic Acid, Sonic hedgehog and Activin are a few examples) to give the cells specific functions. By simulating the environment of a cell, we can induce it into becoming a certain type.


What are some uses of stem cells in curing diseases?


Stem cells are useful in a variety of circumstances. One of the most well-known areas of stem cell research is hematopoietic cells, which create blood and immune cells. Sickle Cell Anemia is a disease where red blood cells are sickle-shaped, instead of donut shaped, so they are less efficient in delivering oxygen to the body. This results in excruciating pain. Stem cells can replace the genetically-fault hematopoietic cells to create properly-shaped RBC. Neurodgenerative diseases, like Parkinson's, can also be improved by replacing dead neurons. And if we can get stem cells to become beta cells that produce insulin, we can finally find a cure for diabetes. The possibilities for cures are virtually endless, although stem cells are not necessarily the final solution for all diseases.
 The types of cells that scientists can manufacture are:

Hematopoietic stem cells create blood cells: red blood cells, B lymphocytes, T lymphocytes, natural killer cells, neutrophils, basophils, eosinophils, monocytes, and macrophages.

 Mesenchymal stem cells create: bone cells (osteocytes), cartilage cells (chondrocytes), fat cells (adipocytes), and connective tissue cells.

Neural stem cells create: nerve cells (neurons) and two categories of non-neuronal cells—astrocytes and oligodendrocytes.

Epithelial stem cells in the lining of the digestive tract create: absorptive cells, goblet cells, paneth cells, and enteroendocrine cells.

Skin stem cells are located in the basal layer of the epidermis and at the base of hair follicles. The epidermal stem cells create keratinocytes, which leads to the formation of a protective layer in the epidermis. The follicular stem cells can help create both the hair follicle and the epidermis.

Embryology

After sexual intercourse sperm must travel through the female genitalia. Once a sperm cell finds an egg, the acrosomal reaction occurs in the head of the sperm (the acrosome) to break the follicular cells surrounding the oocyte. Then, the cortical reaction makes it so that the egg becomes impenetrable by any other sperm, so that only one male gamete nuclei can fuse with the female one, thus beginning fertilization. These two haploid gametes form one diploid zygote. Through cleavage, that single-celled zygote can become a multicellular embryo through mitosis. This creates the blastula, a ball of cells surrounding a liquid cavity. The blastula becomes the gastrula once those cells move to form specific layers. The ectoderm is the outermost layer, responsible for forming skin, hair sweat glands, epithelium, the brain and nervous system structures. The middle layer is known as the mesoderm, responsible for muscles, cartilage, bone, blood, connective tissue, reproductive organs and kidneys. The innermost layer is the endoderm, which forms the digestive and respiratory organs, the endocrine glands, liver, pancreas and gall bladder. At the center of the gastula is the archenteron, a cavity which later shapes the alimentary canal used for food to pass through for digestion. The creation of these specific tissues and organs is known as organogenesis, and is a major distinction between the embryo and the fetus.



http://embryo.soad.umich.edu/index.html