A research team led by Professor Noriyuki Tsumaki of the Center for iPS Cell Research and Application (CiRA) at Kyoto University and Dr. Hidetatsu Ohtani, a former CiRA member who now works as a post doctoral fellow at Osaka University Graduate School of Medicine, has succeeded in directly converting human dermal fibroblasts into induced chondrogenic cells (iChon cells) without passing through an iPS cell stage in a process known as direct reprogramming. This finding has been published in PLOS ONE on October 16, 2013.
Articular cartilage, which is made up of chondrocytes and extracellular material in the form of Type II, Type IX, and Type XI collagens and aggrecan, fulfills the functions of ensuring smooth joint movement and absorbing shocks. Cartilage has little regenerative capacity and is gradually lost due to injury, aging, and other factors.
Normal articular cartilage consists of hyaline cartilage, but when this is lost it is partially replaced by fibrous cartilage. Fibrous cartilage produces Type I collagen and loses the extracellular material structure specific to cartilage. To restore cartilage function, this means that either high-purity hyaline cartilage not containing fibrous cartilage must be prepared and transplanted into the site where cartilage has been lost, or fibrous cartilage must be converted in situ into hyaline cartilage.
One conceivable method of producing cartilage would be to induce it from iPS cells. Alternatively, if it were possible to convert fibroblasts directly into chondrocytes without an intermediate iPS cell stage, chondrocytes could probably be produced in a shorter period of time than via an iPS cell-based method.
In 2011, Professor Tsumaki and his team reported that, by inserting into mouse dermal fibroblasts two reprogramming factors (c-MYC and KLF4) and one cartilage factor (SOX9), they had achieved direct reprogramming into induced chondrogenic cells without passing through a
|Contact: Akemi Nakamura|
Center for iPS Cell Research and Application - Kyoto University