A detailed review article in the June issue of Plastic and Reconstructive Surgery, the official medical journal of the American Society of Plastic Surgeons, has examined the safety and clinical efficacy of fat-derived stem cells. Stem cells from fat, also known as ACSs, are a promising source of cells for use in plastic surgery and regenerative medicine, according to this review, but there are still many questions that remain about them. Much more research is needed in order to completely establish the safety and effectiveness of ASC-based therapies in human patients. The review article was written by ASPS Member Surgeon Rod Rohrich, MD of University of Texas Southwestern Medical Center, Dallas, and his colleagues (Dr. Rohrich is Editor-in-Chief of Plastic and Reconstructive Surgery).
ASCs are very easily procured from humans, since simple procedures such as liposuction can provide more than enough material for therapies. On the average, one gram of fat yields about 5,000 stem cells, whereas the yield from the same quantity of bone marrow is about 1,000 cells (B. M. Strem, K. C. Hicok, M. Zhu et al., “Multipotential differentiation of adipose tissue-derived stem cells,” Keio Journal of Medicine, vol. 54, no. 3, pp. 132–141, 2005.). Once isolated from the fat, ASCs have the capacity to form fat cells, but also bone, cartilage and muscle cells.
From a therapeutic standpoint, ASCs promote the development of new blood vessels (angiogenesis). ASCs are also not recognized by the immune system and they seem to staunch inflammation. According the Dr. Rohrich and is co-authors, “Clinicians and patients have high expectations that ASCs may well be the answer to curing many recalcitrant diseases or to reconstruct anatomical defects.”
Fortunately, there is great interest in ASCs, and this means that the number of studies that examine ASCs or utilize them for experimental treatments have soared. Unfortunately, there is continued concern about the “true clinical potential” of ASCs. In the words of this new article, “For example, there are questions related to isolation and purification of ASCs, their effect on tumor growth, and the enforcement of FDA regulations.”
Rohrich and others conducted a rather in-depth review of all known clinical trials of ASCs. Thus far, most studies have been performed in Europe and Korea, and only three in the United States, to date. This reflects the stringency of FDA regulations.
Most ASC clinical trials to date have been examined the use of ASCs in plastic surgery. In this case, plastic surgeon-researchers have used ASCs for several types of soft tissue augmentation (breast augmentation, especially after implant removal and regeneration of fat in patients with abnormal fat loss or lipodystrophy). Studies exploring the use of ASCs to promote healing of difficult wounds have been reported as well. ASCs have also been used as in so-called soft tissue engineering or tissue regeneration. In these cases, the results have been inconclusive.
Other medical specialties have also made use of ASCs as treatments for other types of medical conditions. For example, ASCs have been studied for used to treat certain blood and immunologic disorders, heart and vascular problems, and fistulas (abnormal connection between an organ, vessel, or intestine and another structure). There are some other studies that have examined the use of ASCs for generating new bone for use in reconstructive surgery. A few studies have reported promising preliminary results in the treatment of diabetes, multiple sclerosis, and spinal cord injury. Perhaps one of the most encouraging results was the complete absence of serious adverse events related to ASCs in any of these studies.
These results are encouraging, but all of these applications are in their infancy. Globally speaking, less than 300 patients have been treated with ASCs, and no standardized protocol exists for the preparation or clinical applications of ASCs. Additionally, there is no consensus as to the number of ASCs required per treatment, or how many treatments are required for the patient to show clinical improvement. Thus Rohrich and his colleagues have taken a “proceed with caution approach.” They conclude that “further basic science experimental studies with standardized protocols and larger randomized controlled trials need to be performed to ensure safety and efficacy of ASCs in accordance with FDA guidelines.”