Note: This section contains technical data and explanations of procedures
Stem cells are present in most tissues. In the past the most commonly used source has been bone marrow. In 2001 Patricia Zuk published her landmark paper demonstrating the presence of stem cells in fat. Fat is now recognised to be a richer source of stem cells than bone marrow. Stem cell numbers in fat do not reduce with age as they do in bone marrow. Fat has become an extremely popular source of stem cells. It is easy to harvest with minimal adverse events associated with the harvesting and often significant improvement in health because of the harvesting. fat is often present in large volumes.
How refined do stem cells need to be?
If we transfer stem cells as intact fat grafts from liposuction (lipoaspirate) the stem cell concentration will be approximately half that which was present in the original donor site. I.E. Liposuction removes twice as many Adipocytes (fat cells) than stem cells. This means that after liposuction the remaining fat is stem cell enriched, less inflammed and healthier. This stem cell poor lipoaspirate is still potent enough to produce new nerve growth, fibroblast and collagen, new capillaries, etc.
If we reduce the number of fat cells in the lipoaspirate but retain the stem cell numbers we then have condensed lipoaspirate. This is thought to be associated with fewer adverse events than lipoaspirate. When it becomes possible to selectively remove adipocytes we will have stem cells attached to their own scaffold. The advantages of this include easier cell preparation which means less cost to the patient and we know that as the cells are anchored to their scaffold they will not migrate and be lost to the target.
Separating the cells from fat and adding them to lipoaspirate gives stem cell enriched lipoaspirate which can usefully contain 300% more cells.
Dissolving the collagen structure that holds all the cells together allows cell separation in a centrifuge. This will yield a Stromal Vascular Fraction (SVF) pellet of cells. This pellet of SVF cells is proving to be more potent than pure adipose derived stem cells. We have used this SVF pellet to treat Osteoarthritis of the knee with great success. Other groups using pure stem cells to treat OA have been dissappointed. This appears to indicate that the stem cells work better when accompanied by all the other cells present in the SVF. Purifying stem cells involved expanding the cells in culture. This is expensive, takes time and introduces the risk of infection and a theoretical risk of mutation during cell multiplication. Stem cells from bone marrow are present in such small numbers that they must be expanded in culture to be a clinically useful treatment.