Stem cell therapy has the potential to treat a broad range of acute and chronic degenerative diseases. These applications include: hematopoietic cells for blood diseases and cancer, myocardial and endothelial vascular tissue for cardiovascular disease, congestive heart failure, myocardial infarction and other cardiovascular disease skin cells for dermatological conditions, retinal pigment epithelium cells as treatment for macular degeneration and retinal pigmentosis, neural cells for spinal cord injury, Parkinson's disease and other neurodegenerative diseases, pancreatic islet ß cells for diabetes, liver cells for hepatitis and cirrhosis, cartilage cells for arthritis, and lung cells for a variety of pulmonary diseases. As populations age in developed countries, the need to treat increasing numbers of people with these disorders is likewise increasing.
With increased attention being paid to the need for these technologies, researchers have been reporting promising results in several areas.
In results reported in 2009, scientists from MIT found that stem cells can improve stem cells’ ability to regenerate vascular tissue by equipping them with genes that produce extra growth factors. These results were produced in mice; specially developed nanoparticles were used to deliver vascular endothelial growth factor to stem cells removed from the mouses’ bone marrow. The enhanced stem cells were then implanted into damaged tissue, where they regenerated blood vessles near the injury, thus allowing the damaged tissue to survive.
Other results reported in 2009 (Proceedings of the National Academy of Sciences, September 2009) showed researchers have had some success in engineering human tissue patches for cardiovascular repair. These clinicians (from the University of Washington, led by Dr. Charles Murry) created disk-shaped patches measuring less than a millimeter up to a half-inch in diameter decided to examine the possibility of creating new tissue with supply lines for oxygen and nutrients needed by living cells. Previously, heart tissue patches composed of only heart muscle cells could not grow big enough or survive long enough to adhere to the heart once implanted. Researchers added to the heart muscle cell mixture two other types of cells similar to those inside blood vessels and cells that provide vascular muscular support. All of the heart muscle cells were derived from embryonic stem cells or a variety of more mature sources such as umbilical cord blood. The result was seen in the formation of tissue containing tiny blood vessels.
On the orthopedic front, adult stem cells were used to regrow a 14-year-old boy’s missing cheekbones at the Cincinnati Children’s Hospital Medical Center. The technique used reengineered autologous stem cells.
In another example, scientists at the University of Bristol developed new scaffolds that can be used to grow such tissues as skin, nerves and cartilage. They built the scaffolds by using proteins from alpha helices to create long fibers (hydrogelating self-assembling fibers or hydrogels).
Unmet Clinical Needs
Allotransplantation (the transplanting of donated organs or tissues from a cadaver or a living donor) works effectively but has a couple of significant drawbacks. First, the number of organs available for donation is always far smaller than the number of organs and tissues needed by patients. According to the U.S. Department of Health and Human Services, there were more than 102,000 people in the United States alone waiting for donated organs in 2007; many of those on the waiting list die before a suitable organ or tissue becomes available. Secondly, even when an organ becomes available, organ transplant is a very expensive procedure. In addition, if the procedure is successful, the transplant recipient may often need to take immunosuppressive drugs, sometimes for life. Yet another factor in the equation is the cost of keeping patients alive while awaiting a donor, or caring for them until they die if no donor is found.
One solution to this would be to use genetically designed pigs, animals whose organs would present minimal immunologic reaction to the host. Such animals (the pig is often cited because most of its internal organs are similar to human organs) could potentially present an unlimited supply of organs for donation to and implantation in humans.
Designing a genetically engineered pig that is capable of carrying human immune proteins has been the focus of select researchers at the Shanghai Institute of Biochemistry and Cell Biology. Results published in 2009 in the Journal of Molecular Cell Biology showed how the scientists successfully reprogrammed pig skin and bone marrow cells into an embryo-like state with the potential to form every type of body tissue. The successful creation of pig pluripotent stem cells would enable engineering of transgenic animals for organ transplantation purposes. The embryonic or induced stem cellscould be used to modify the immune-related genes in the pig to make the pig’s organs compatible to the human immune system, thus allowing the pigs to be used as organ donors without triggering an adverse reaction from the patient’s own immune system.
Another solution would be, of course, tissue engineering and cell therapy. There are hundreds of companies working in the field of tissue engineering, expanding the procedures, devices, cell-based products, biomaterial-based products and other products for the repair and regeneration of damaged tissues.
See the current (2011) market for tissue engineering and cell therapy by area of clinical focus.
Source: MedMarket Diligence, LLC; Report #S520, "Tissue Engineering, Cell Therapy and Transplantation: Products, Technologies & Market Opportunities, Worldwide, 2009-2018."