Osiris Reports Expansion from Adult Stem Cells
Introduction
New Interest in Stem Cells
Promise for Regenerative Medicine
Introduction (Back to Top)
Recent announcements of stem cell success stories indicate that this field is just beginning to heat up. In the April 2, 1999 issue of Science, researchers at Osiris Therapeutics, Inc. (Baltimore, MD) showed that adult stem cells, referred to as mesenchymal stem cells (MSCs) are capable of forming multiple normal human tissues. In particular, MSCs undergo substantial expansion starting from a single stem cell, and the resulting expanded cell population can be maintained as stem cells in culture or induced selectively to form bone, cartilage, or fat.
According to the report, MSCs are maintained throughout life and form normal tissue through a process similar to early tissue formation. Adult stem cells first undergo multiple divisions (proliferation), after which they proceed down a particular tissue development pathway (commitment), leading ultimately to the formation of specialized cells (differentiation) and the fabrication of unique structural components (maturation) characteristic of healthy, mature connective tissue. Adult stem cells are responsible for the normal replacement and regeneration of human connective tissues, including bone marrow stroma, bone, cartilage, muscle, tendon, ligament, and fat. The tissue formation process is called mesengenesis.
New Interest in Stem Cells (Back to Top)
According to Mark F. Pittenger, Associate Director of Muscle Research and Cell Biology at Osiris and primary author of the Science publication, his work proves that adult stem cells isolated from donor bone marrow can be prodded into forming tissues from a single cell. "These cells are fascinating in their ability to respond to stimuli," Pittenger said. "The growth and differentiation conditions for each lineage, such as bone, cartilage, and fat, are quite different, involving a combination of growth factors, nutrients, spatial organization, and mechanical forces. It has taken several years to refine our assays, but we now have a clearer understanding of the differentiation mechanisms. When we saw that human adult stem cells could be expanded from a single cell that would differentiate to all three lineages, that really clinched it. Each of the lineages that we reported in Science has important health implications associated with them, ranging from the direct regeneration of bone and cartilage injuries, to the treatment of osteoporosis, osteoarthritis, and obesity."
Promise for Regenerative Medicine (Back to Top)
Daniel Marshak, Chief Scientific Officer for Osiris as well a co-author on the Science paper, points out that adult stem cells are responsible for tissue turnover throughout life. "The blood-forming stem cell, or hematopoietic stem cell (HSC), was the first fully characterized adult stem cell. The adult MSC has now been established, and several others may follow." According to Marshak regeneration of damaged or diseased tissue based on the use of adult stem cells will become a new area of medicine. "The new medical paradigm confirms what developmental biologists have long maintained, namely that tissue regeneration recapitulates the normal developmental pattern. Adult stem cells retain this developmental capability, they have been well-characterized, and their growth and differentiation can be controlled."
Osiris is developing multiple products based on adult MSCs. In addition, the company is conducting a clinical trial for its first product, Stromagen, a patient-derived stem cell infusion product for treating breast cancer following chemotherapy. Osiris is banking on the possibility that practical applications of adult stem cells is not 10–15 years away, but reasonably close to commercialization for treating cancer, immune disorders, orthopedic injuries, transplant medicine, congestive heart failure, and degenerative diseases.
For more information: Mark Pittenger, Associate Director, Osiris Therapeutics, Inc., 2001 Aliceanna Street, Baltimore, MD 21231. Tel: 410-522-5005; Fax 410-522-6999; E-mail: mpittenger@osiristx.com.