Foreign body-induced granulation tissue: A novel source of adult stem cells

An inert foreign body placed in the subcutaneous tissue induces new tissue that encapsulates the foreign body (called granulation tissue). In a new study published in the journal Translational Research, Dr. Jilpa Patel and her group at the Cook County Hospital and Hektoen Institute of Medicine in Chicago have isolated and characterized adult stem cells from granulation tissue in rats.

These stem cells called granulation-tissue stem cells (GTSC) can be multiplied infinitely outside the body, and are rich in growth and other stem cell factors. GTSC readily differentiated to bone, cartilage and fat cells when cultured in specialized media, an important property of multi-potent stem cells. When injected into the body with an injured organ, GTSC recognized and engrafted only to the injured organ and not to normal organs. It was possible to freeze GTSC for long-term storage without loss of potency. Because GTSC can be easily obtained from the patient’s own body and can be stored long-term, it can serve as an excellent source of stem cells for use in repair of damaged organs.

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, the use of adult tissue derived stem cells (bone marrow cells being the commonest of adult stem cells) is free of such concerns and therefore of immediate utility.  Adult stem cells have been obtained from many tissue including bone marrow, adipose tissue, skin, hair, dental pulp, and omentum. Because granulation tissue derived stem cells 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.  Presently, the authors are conducting further studies to assess the utility of GTSC in kidney disease, liver disease and osteoarthritis.

This article is based on the manuscript ‘Foreign body-induced granulation tissue is a source of adult stem cells’ published in the journal Translational Research. (Citation: doi: 10.1016/j.trsl.2009.08.010)