A Scientific Editorial - Articular Cartilage Regeneration

More Evidence of Articular Cartilage Regeneration

What happens to articular cartilage when it is subjected to mechanical trauma? It is important to consider the main issue. Can adult articular cartilage respond to appropriate stimuli by an increase in its synthetic activities for DNA and matrix components? In other words, can chondrocytes replicate and make cartilage? Central to this discussion is the consideration of the ability of any tissue to increase its rate of DNA and protein synthesis. Regardless of the tissue involved, the process of repair is a cellular one in the sense that fibroblasts, or specific cells (osteoblasts, chondrocytes for example), must synthesize the repair material. For the most part, these are “new” cells that evolve by cell replication and modulation of existing cells, or from cells that have migrated either from the margins of the wound or from blood vessels entering the tissue. It is therefore important to recognize that DNA replication and cell division are essential characteristics of any repair process.

The confusion in regard to articular cartilage repair stems from the fact that chondrocytes from immature cartilage are capable of dramatic repair and synthesis, whereas aging chondrocytes show much lower rates of cell replication.^[26,27] This is where the notion of “cartilage cells don’t replicate” stems from. The problem with this logic is that a normal adult chondrocyte is phenotypically different from an injured chondrocyte. Analysis of cartilage from joints with osteoarthritis has demonstrated, over and over again, an increased number of cells in clones and evidence for DNA synthesis by a number of means including 3H-thymidine metabolic studies, autoradiography, and even histological demonstration of mitotic figures.^{Surgery. 1973;55B:588-594.<br><br>30. O’Driscoll S. Current concepts review- The healing and regeneration of articular cartilage. Journal of Bone and Joint Surgery. 1998;80:1795-1812.</p>', 230)" onmouseout="hideddrivetip()" href="/prolotherapy/call-to-action#Resources">[28,29,30]} These data suggest that under circumstances of chronic injury, such as is seen in osteoarthritis or trauma, chondrocytes are capable of mounting a significant reparative response and can replicate their DNA to form new cells.^[31] This is fact. Chondrocytes can divide, and do so in the adult animal/ human with osteoarthritis and from other stimuli. Ample evidence now exists that articular chondrocytes from immature and adult animals can vary the rate at which they make cartilage matrix necessary for repair. This rate of proteoglycan synthesis can change in response to such diverse physical and pathological states as osteoarthritis (as discussed), altered hydrostatic pressure, varied oxygen tension, alternations in pH, calcium concentration, substrate concentration, and the presence of growth hormone (as discussed), growth factors, ascorbate, vitamin E, and so on.^[32-36]I could easily elaborate on each of these, but the reader is encouraged to check the references for further information. Therefore, it is reasonable to conclude from the above that injured adult articular cartilage chondrocytes have the capacity to substantially increase their rate of matrix synthesis, and that the possibility exists of chondrocyte participation in the repair of articular cartilage. All that is really needed is a method to stimulate that repair maximally. This is where Prolotherapy fits in.