Researchers identify a novel source of adult stem cells: Foreign body-induced granulation tissue

In a pioneering new study published in the journal Translational Research, Dr. Jilpa Patel and her research group at Hektoen Institute of Medicine and Cook County Hospital in Chicago have isolated and characterized adult stem cells from granulation tissue in rats. A granulation tissue is a new regenerating tissue formed in response to an inert foreign body placed in the subcutaneous tissue. This is the first time a study has shown that such a regenerating granulation tissue is replete with stem cells that are rich in growth factors. These stem cells called granulation-tissue stem cells (GTSC) can be easily obtained, and multiplied infinitely outside the body to get large number of stem cells. GTSC are ‘pluripotent’ stem cells meaning they are capable of becoming many different cell types like bone, cartilage and fat cells under the right conditions. When injected into the body with an injured organ, GTSC engraft only to the injured organ and not a to normal organ, which shows that these stem cells have the propensity to recognize and reach injured organs in the body. This is vital since it would now be possible to give a peripheral (intravenous) injection of these stem cells for treatment of organ damage. Another important finding reported in this study is that GTSC can be frozen for long-term storage without loss of potency. According to Dr. Patel, GTSC can serve as an excellent source of stem cells for the treatment of damaged organs because they are pluripotent stem cells that can be easily obtained from the patient’s own body, multiplied infinitely outside the body, and can be stored long-term.

Stem cells are cells that have the ability to renew themselves continuously as well as differentiate to give rise to diverse cell types. Stem cells are by and large categorized as either a) embryonic stem cells, that are obtained from the inner cell mass of an embryo or b) adult stem cells, those that are derived from adult tissues. The use of embryonic stem cells is controversial as it is hampered by ethical, political and safety concerns. In contrast, adult tissue derived stem cells (bone marrow cells being the commonest of adult stem cells) are free of such concerns and therefore hold tremendous potential for their use in human medicine.

Adult stem cells have been isolated from many tissue including bone marrow, adipose tissue, skin, hair, dental pulp, and omentum. Because granulation tissue derived stem cells (GTSC) described by Dr. Jilpa Patel in this study are obtained from a rapidly regenerating granulation tissue, they are activated stem cells, and therefore they could prove to be more potent than other adult tissue-derived stem cells. Indeed in the preliminary studies conducted by the authors to assess the utility of GTSC they have found incredible results for the treatment of kidney disease and osteoarthritis and further studies are ongoing. In conclusion, the authors of this study have shown that a regenerating granulation tissue is an abundant and unique source of adult stem cells, which could be used for repair and regeneration of damaged tissues.

Source - Translational Research doi: 10.1016/j.trsl.2009.08.010