Stem cell research offers unprecedented opportunities for developing new medical therapies for debilitating diseases and a new way to explore fundamental questions of biology. Stem cells are unspecialized cells that can self-renew indefinitely and also differentiate into more mature cells with specialized functions. Research on human embryonic stem cells, however, is controversial, given the diverse views held in our society about the moral and legal status of the early embryo. The controversy has encouraged provocative and conflicting claims both inside and outside the scientific community about the biology and biomedical potential of both adult and embryonic stem cells. From “Cells and the Future of Regenerative Medicine”
Certain clinical procedures make use of adult cells (from the patient or from another source) to enhance the recovery/regeneration of the structure and/or function of tissue and organs. As an example, a procedure is currently in a clinical trial to use a patient’s muscle-derived stem cells to treat urinary incontinence. Also studies are underway on the use of patient-derived stem cells to treat certain cardiac ailments.
Cells that have both the capacity to self-renew (make more stem cells by cell division) as well as to differentiate into mature, specialized cells.
There are many sources of stem cells. Autologous cells are derived or transferred from the same individual's body. Allogeneic cells are genetically different but belong to or obtained from the same species, such as cells that are obtained from one human that would be used to treat another person.
Embryonic stem (ES) cells are cells derived from the inner cell mass of developing blastocysts. An ES cell is self-renewing (can replicate itself), pluripotent (can form all cell types found in the body). There are ongoing studies in multiple laboratories to further characterize and assess the capabilities of various cell harvesting techniques and the effectiveness of carious applications
In general, scientists and clinicians believe that stem cells have the potential to help repair many deficiencies because of the cells ability to be modified into different functional adult cell types. This repair/replacement mechanism can serve as a potential source of replacement cells to treat numerous diseases. So for diseases in which there is tissue degeneration cell therapy can be a potential candidate for facilitating repair. Examples include heart disease, burns, Type 1 diabetes and possibly spinal cord injury, stroke, arthritis, muscular dystrophy, liver disease and Parkinson's diseases.
Adult stem cell replacement, through bone marrow transplantation with a matched donor is a routine treatment for blood cancers and other blood disorders. The clinical trials using a patient’s stem cells to treat urinary incontinence and certain cardiac ailments is an exciting and emerging field.
Scientists have a lot more to learn about stem cell characteristics, the optimal means to harvest adult stem cells, and the best way to utilize these cells in a clinical setting.
Another need is to learn more on the best way to grow stem cells so that there is a sufficient quantity to have an effective treatment.
Some scientists believe that embryonic and fetal stem cells are more versatile than adult stem cells. However, many scientists are still working on developing proper conditions to differentiate embryonic stem cells into specialized cells. As embryonic stem cells grow very fast, scientists must be very careful in fully differentiating them into specialized cells. Otherwise, any remaining embryonic stem cells can grow uncontrolled and form tumors.
The next challenge is to be sure that the injected cells do not set off an immune response. If the cells are the patient’s own cells, this should not be an issue.
Adult stem cells are distinct from cells isolated from embryos or fetuses and are found in tissues that have already developed, as in animals or humans after birth. These cells can be isolated from many tissues. However, the most common place to obtain these cells is from the bone marrow (typically harvested from the hip).
There are different types of stem cells found in the bone marrow, including hematopoietic stem cells, endothelial stem cells, and mesenchymal stem cells. It has long been known that hematopoietic stem cells form blood, endothelial stem cells form the vascular system (arteries and veins), and mesenchymal stem cells form bone, cartilage, muscle, fat, and fibroblasts.
The most publicized use for stem cells is their ability to form different types of cells that can be used to restore or replace damaged tissue. Scientists have shown in animal studies that mouse embryonic stem cells could contribute to every tissue in the adult mouse. Hence, many believe that human embryonic stem cells would also have this property (pluripotent stem cells). Scientists will need to conduct further studies to compare human embryonic stem cell lines for their potential in tissue repair relative to effectiveness of adult stem cells for tissue repair.
In general, scientists and clinicians believe that stem cells have the potential to help repair many deficiencies because of the cells ability to be modified into different functional adult cell types. This repair/replacement mechanism can serve as a potential source of replacement cells to treat numerous diseases. So for diseases in which there is tissue degeneration cell therapy can be a potential candidate for facilitating repair. Examples include heart disease, burns, Type 1 diabetes and possibly spinal cord injury, stroke, arthritis, muscular dystrophy, liver disease and Parkinson's and diseases.
Adult stem cell replacement, through bone marrow transplantation with a matched donor is a routine treatment for blood cancers and other blood disorders. The clinical trials using a patient’s stem cells to treat urinary incontinence and certain cardiac ailments is an exciting and emerging field.
Hematopoietic stem cells (HSCs), present in the bone marrow and precursors to all blood cells, are currently the only type of stem cells commonly used for therapy. Doctors have been transferring HSCs in bone marrow transplants for more than 40 years. Advanced techniques for collecting or "harvesting" HSCs are now used to treat blood disorders such as leukemia and lymphoma.
Stem cells have traditionally been grown in culture dishes in incubators at body temperature (~37ºC) under high humidity. The challenge for scientists is to grow enough stem cells in an undifferentiated state, that is without having them differentiate into more specialized cell types, and also to learn how to make the cells differentiate into specialized cells, when that becomes necessary. Bioreactor technologies are improving the production of stem cells, as bioreactors permit the growth of cells in 3 dimensions, vs. a Petri dish that grows cells in 2 dimensions.