Ming-Feng Hsueh et al discovered that proteins of cartilage in hip, knee and ankle in humans showed a pattern of regeneration similar to that of highly regenerative animals, such as axolotls. Turnover of insoluble collagen has been earlier suggested to be very limited in human adult cartilage. In this study, researchers could unmask a position-dependent change in protein turnover, reflecting innate tissue repair capacity in cartilages of human lower limb based on the age of proteins within the cartilage. They found that the age of cartilage largely depended on the position of it in the body. Cartilage in the ankles had the highest amount of young proteins compared to the knees, while hip cartilage had the lowest amount of young proteins, which reciprocated their tissue repair mechanism. Researchers could also find a similar difference in the quantity of microRNA levels within the cartilage, which was highest in ankles compared to knee and hip cartilage. The study found how specific microRNAs helped drive the formation of newer proteins in the collagen helping in repair and regeneration of the tissue. Thus, researchers suggest exploiting the new findings to study and help enhance joint repair and human limb regeneration in the future.
Source: Science Advances 09 Oct 2019: Vol. 5, no. 10, eaax3203 DOI: 10.1126/sciadv.aax3203 https://advances.sciencemag.org/content/5/10/eaax3203