Endogenous repair theory enriches construction strategies for orthopaedic biomaterials: a narrative review

Yizhong Peng, Jinye Li, Hui Lin, Shuo Tian, Sheng Liu, Feifei Pu, Lei Zhao, Kaige Ma, Xiangcheng Qing, Zengwu Shao

Figure 4. Anatomical structure of an intervertebral disc and identification of the stem cell niche and hypothetical migration paths. (A) The potential stem cell niche is in the perichondrium region adjacent to the epiphyseal plate and outer layers of the annulus fibrosus (AF). In the hypercellular region 1 (HCR 1), the cells are densely distributed, and this is where the stem cell niche is located; while in the hypercellular region 2 (HCR 2), the cells are relatively dispersed and morphologically mature. (B) A magnification of the region of interest shows slow cycling stem/progenitor cells (outlined in orange), the transit amplifying cells (outlined in green), and differentiated cells (outlined in white).153 CEP: cartilage endplate; NP: nucleus pulposus.