Mesenchymal stem cells (MSCs) are multipotent cells found in multiple human adult tissues, including bone marrow, synovial tissues, and adipose tissues. Since they are derived from the mesoderm, they have been shown to differentiate into bone, cartilage, muscle, and adipose tissue.[1][2] MSCs from embryonic sources have shown promise scientifically while creating significant controversy. As a result, many researchers have focused on adult stem cells,[3] or stem cells isolated from adult humans that can be transplanted into damaged tissue.
Because of their multi-potent capabilities, mesenchymal stem cell (MSC) lineages have been used successfully in animal models to regenerate articular cartilage and in human models to regenerate bone.[4][5][6] Recent research demonstrates that articular cartilage may be able to be repaired via the percutaneous introduction of mesenchymal stem cells (MSC's).[7]
Stem cells, as a concept, originated as a theory in the 19th century to potentially allow certain tissues to self-renew. There are five types of stem cells, and MSC's are multi-potent, meaning they are cells that have the ability to develop into more than one type of specialized cell. Mesenchymal stem cells were originally discovered and studied as fibroblast-colony-forming cells in guinea-pig bone marrow and spleen cells by Friedenstein in the 1970s.[8] This study proved that the colony-forming units of bone marrow-derived stem cells were able to form cartilage once they were transplanted into a diffusion chamber.[9] The results of this study set the stage for future research by indicating the differentiation capacity of MSC's.[citation needed]