Cartilage regeneration and tissue engineering has proven more difficult than initially expected. It is a tissue with a deceptively complex structure, in which important mechanical properties necessary to its load-bearing role are derived from the details of that structure. Simply culturing cartilage cells is far from enough to produce a useful end result, and researchers have only recently made inroads into producing tissue engineered cartilage that is somewhat like the real thing. In this work a novel approach is taken to produce grafts for injured joint cartilage:
Cartilage lesions in joints often appear in older people as a result of degenerative processes. However, they also regularly affect younger people after injuries and accidents. Such defects are difficult to repair and often require complicated surgery and long rehabilitation times. A new treatment option has now been presented by a research team: nasal cartilage cells can replace cartilage cells in joints.
[Scientists] were especially surprised by the fact that in the animal model with goats, the implanted nasal cartilage cells were compatible with the knee joint profile; even though, the two cell types have different origins. During the embryonic development, nasal septum cells develop from the neuroectodermal germ layer, which also forms the nervous system; their self-renewal capacity is attributed to their lack of expression of some homeobox (HOX) genes. In contrast, these HOX genes are expressed in articular cartilage cells that are formed in the mesodermal germ layer of the embryo.
Cartilage cells from the nasal septum (nasal chondrocytes) have a distinct capacity to generate a new cartilage tissue after their expansion in culture. In an ongoing clinical study, the researchers have so far taken small biopsies (6 millimeters in diameter) from the nasal septum from seven out of 25 patients below the age of 55 years and then isolated the cartilage cells. They cultured and multiplied the cells and then applied them to a scaffold in order to engineer a cartilage graft the size of 30 x 40 millimeters. A few weeks later they removed the damaged cartilage tissue of the patients' knees and replaced it with the engineered and tailored tissue from the nose.