Many overseas clinics advertise miraculous stem cell therapies for a wide range of incurable diseases. This phenomenon is called stem cell tourism and is currently a source of concern for reputable stem cell scientists. International (and even domestic) clinics are offering up therapies that have not been tested for safety or even for effectiveness. In the past few years, some patients who visited those clinics have died as a result of receiving unproven, untested stem cells.
Human pluripotent stem cells, called human embryonic germ (hEG), also could be derived from fetal material obtained from medically terminated pregnancies (23). Although obtained from different sources by different laboratory processes, both hES and hEG cells have been demonstrated to be pluripotent (capable of forming all cells and tissues in the body) (24). Several lines of hES cells have been produced, including some that were clonally derived (25).
More than just a cheesy song from The Sound of Music, edelweiss are tiny flowers that withstand harsh alpine climes. They are full of leontopodic acids, which are strong antioxidants. An Italian company that produces the edelweiss stem cells explains an interesting technique in which they chop up some of the plant’s biomass, and the surrounding cells revert to stem cells in order to protect the plant with a wound healing tissue called callus.
Unlike the use of zygotes containing the combined genetic material from a male and a female, as in IVF, NT results in a "clone" of the donor of the adult cell. Implanting such a blastocyst into a woman, termed "reproductive cloning," would result in an individual with the exact genetic makeup of the donor of the nucleus. Agreement has been reached that reproductive cloning of humans is unethical and should not be permitted.
Alopecia as an outcome of chemotherapy for a malignancy can be very distressing. The loss of hair usually is temporary and the hair will grow back after the course of treatment is completed. Male patients may feel more comfortable wearing a hat or cap when out in public. Female patients who wish to wear a wig are encouraged to obtain one that is lightweight and the same color as their hair. Having a hairdresser cut the wig to the patient's usual hair style can increase self-esteem. A kerchief or head scarf can be worn around the house if it is more comfortable than a wig. Receipts for wigs, hairpieces, and other headcovering should be saved; they are tax-deductible medical expenses when related to chemotherapy.
Perhaps the most important potential application of human stem cells is the generation of cells and tissues that could be used for cell-based therapies. Today, donated organs and tissues are often used to replace ailing or destroyed tissue, but the need for transplantable tissues and organs far outweighs the available supply. Stem cells, directed to differentiate into specific cell types, offer the possibility of a renewable source of replacement cells and tissues to treat diseases including Parkinson's and Alzheimer's diseases, spinal cord injury, stroke, burns, heart disease, diabetes, osteoarthritis, and rheumatoid arthritis.
Like human stem cells, plant stem cells are undifferentiated cells that can divide to produce more stem cells or become specialized cells. Sources for the stem cells range from flowers to apples to cranberries and other plant sources. “When added to a skin care cream or serum, usually they are first broken open, and then they release high concentrations of antioxidants and growth factors,” says Shamban.
There are two types of identification tests for female pattern baldness: the Ludwig Scale and the Savin Scale. Both track the progress of diffused thinning, which typically begins on the crown of the head behind the hairline, and becomes gradually more pronounced. For male pattern baldness, the Hamilton–Norwood scale tracks the progress of a receding hairline and/or a thinning crown, through to a horseshoe-shaped ring of hair around the head and on to total baldness.
Embryonic stem cells and embryonic stem cell lines have received much public attention concerning the ethics of their use or non-use. Clearly, there is hope that a large number of treatment advances could occur as a result of growing and differentiating these embryonic stem cells in the laboratory. It is equally clear that each embryonic stem cell line has been derived from a human embryo created through in-vitro fertilization (IVF) or through cloning technologies, with all the attendant ethical, religious, and philosophical problems, depending upon one's perspective.
Due to the nature of embryonic stem cell research, there is a lot of controversial opinions on the topic. Since harvesting embryonic stem cells necessitates destroying the embryo from which those cells are obtained, the moral status of the embryo comes into question. Scientists argue that the 5-day old mass of cells is too young to achieve personhood or that the embryo, if donated from an IVF clinic (which is where labs typically acquire embryos from), would otherwise go to medical waste anyway. Opponents of ESC research counter that any embryo has the potential to become a human, therefore destroying it is murder and the embryo must be protected under the same ethical view as a developed human being.
Routine use of stem cells in therapy has been limited to blood-forming stem cells (hematopoietic stem cells) derived from bone marrow, peripheral blood, or umbilical cord blood. Bone marrow transplantation is the most familiar form of stem cell therapy and the only instance of stem cell therapy in common use. It is used to treat cancers of the blood cells (leukemias) and other disorders of the blood and bone marrow.
In many cases testing the cells in a single animal model doesn’t provide enough information. Most animal models of disease don’t perfectly mimic the human disease. For example, a mouse carrying the same mutation that causes cystic fibrosis in humans doesn’t show the same signs as a person with the disease. So, a stem cell therapy that treats this mouse model of cystic fibrosis may not work in humans. That’s why researchers often need to test the cells in more than one animal model.
Alopecia can be divided into disorders in which the hair follicle is normal but the cycling of hair growth is abnormal and disorders in which the hair follicle is damaged. Androgenetic alopecia is the most common cause of hair loss in women. Other disorders include alopecia areata, telogen effluvium, cicatricial alopecia, and traumatic alopecias. The diagnosis is usually based on a thorough history and a focused physical examination. In some patients, selected laboratory tests or punch biopsy may be necessary. Topically administered minoxidil is labeled for the treatment of androgenetic alopecia in women. Corticosteroids and other agents are typically used in women with alopecia areata. Telogen effluvium is often a self-limited disorder. Because alopecia can be devastating to women, management should include an assessment for psychologic effects.
Human embryonic stem cells also represent a new technology for pharmaceutical research and development. Until now, the only cell lines available for this work were either animal or abnormal transformed human cells. Permanent, stable sources for normal human differentiated cells may be developed for drug screening and testing, drug toxicology studies, as well as new drug target identification (92–94). In addition, hES cells may also allow the creation of in vivo models of human disease for drug development as a superior alternative to current mouse models.
Klug et al. were the first to show that ES-derived cardiomyocytes, selected using an antibiotic selection cassette (Figure 2) and injected into the hearts of dystrophin-deficient MDX mice, were able to repopulate the myocardial tissue and integrate with host myocardial tissue (47). Enriched populations of cardiomyocytes were obtained by introducing into ES cells a neomycin resistance gene under the control of the α-cardiac myosin heavy chain promoter. On differentiation, only cardiac-committed cells expressing the antibiotic resistance gene can survive when treated with neomycin. Similarly, cardiomyocytes with a ventricular phenotype have been selected using the ventricular-specific myosin light chain isoform 2v promoter controlling the expression of green fluorescent protein (49,50). So far, however, no study has investigated the engraftment of specific subpopulations of ES-derived cardiomyocytes, such as ventricular, atrial, or pacemaker cells. Whether these approaches can generate sufficient numbers of cardiac cells suited for myocardial repair in vivo remains to be established. Ideally, understanding how to control cardiomyocyte differentiation would maximize proliferation of cardiac progenitors cells in culture while impeding their terminal differentiation, which should be undergone after transplantation.
A substantially blemished face, back and limbs could point to cystic acne. The most severe form of the condition, cystic acne, arises from the same hormonal imbalances that cause hair loss and is associated with dihydrotestosterone production. Seborrheic dermatitis, a condition in which an excessive amount of sebum is produced and builds up on the scalp (looking like an adult cradle cap), is also a symptom of hormonal imbalances, as is an excessively oily or dry scalp. Both can cause hair thinning.
Stem cells have also been shown to have a low immunogenicity due to the relatively low number of MHC molecules found on their surface. In addition, they have been found to secrete chemokines that alter the immune response and promote tolerance of the new tissue. This allows for allogeneic treatments to be performed without a high rejection risk.
Embryonic stem cells are derived from embryos at a developmental stage before the time that implantation would normally occur in the uterus. Fertilization normally occurs in the oviduct, and during the next few days, a series of cleavage divisions occur as the embryo travels down the oviduct and into the uterus. Each of the cells (blastomeres) of these cleavage-stage embryos are undifferentiated, i.e. they do not look or act like the specialized cells of the adult, and the blastomeres are not yet committed to becoming any particular type of differentiated cell. Indeed, each of these blastomeres has the potential to give rise to any cell of the body. The first differentiation event in humans occurs at approximately five days of development, when an outer layer of cells committed to becoming part of the placenta (the trophectoderm) separates from the inner cell mass (ICM). The ICM cells have the potential to generate any cell type of the body, but after implantation, they are quickly depleted as they differentiate to other cell types with more limited developmental potential. However, if the ICM is removed from its normal embryonic environment and cultured under appropriate conditions, the ICM-derived cells can continue to proliferate and replicate themselves indefinitely and still maintain the developmental potential to form any cell type of the body (quot;pluripotencyquot;; see Fig. 1.2: Characteristics of ESCs). These pluripotent, ICM-derived cells are ES cells.