Figure 4.

Cell sheets adhere, remain localized, and induce cartilage regeneration in vivo without any additional support materials. Histological and immunohistochemical staining of rat knee cross-sections 4-weeks post cartilage sheet transplantation show close interfacing with the native cartilage and (a) areas of positive hyaline-like regeneration (Safranin-O), correlating to (b) retention and viability of human cells (hVimentin—brown color) in trochlear groove chondral defects. Regenerated tissue filling the defect at 4 weeks post-transplantation (c) macroscopically and (d) histologically (Safranin-O) (right corner boxes shows defect only controls) resembles native cartilage. Scale bars = 200 μm. Adapted and reprinted from Kondo M., Kameishi S., Grainger D. W. & Okano T. Novel therapies using cell sheets engineered from allogeneic mesenchymal stem/stromal cells. Adapted with permission from Emerg. Top. Life Sci. 4 (6): 677–689 (2020). Copyright 2020 Portland Press.