Bone marrow-derived cells have the unique ability to differentiate into target cells and promote healing activities. However, these abilities are expressed only in suitable environments. Human urethral sphincters with post-surgical ISD-related urinary incontinence have not been investigated to determine if the damaged regions provide such an environment that supports regeneration by bone marrow-derived cells. To achieve clinically

significant regeneration with these cells, it may be necessary to combine them with tissue engineering techniques that utilize scaffolds and/or growth factors.2 In any case, we clearly show that in rabbits the implantation of bone marrow-derived cells accelerates MK-8669 cost Selleck SAHA HDAC the recovery of freeze-injured urinary sphincters compared to cell-free injections. At 7 and 14 days after implantation, we determined if the cells organized into the reconstructed muscle layer structures are derived from the implanted autologous bone marrow-derived cells. The tissues are double-stained with GFP antibody in combination with striated muscle cell-, smooth muscle cell-, or myoblast-differentiation marker antibodies. At 7 days, some of the implanted cells identified by the presence of antibody-labeled GFP are simultaneously

positive for myoglobin Protirelin antibody. These double positive cells show that the implanted autologous cells differentiate into striated muscle cells. These differentiated cells are widely distributed within the reconstructed muscle layers (Fig. 4a). At 14 days after implantation, the double-labeled cells appeared to form contacts among themselves, creating striated muscle layer structures (Fig. 4b). Other GFP-positive implanted cells are also simultaneously positive for

SMA antibody. These cells show that the implanted cells differentiate into smooth muscle cells. Such cells are also widely distributed within the reconstructed muscle layers (Fig. 4c). Similarly, these double-labeled cells appear to form contacts among themselves, creating smooth muscle layer structures (Fig. 4d). In addition, the striated- and smooth-muscle differentiated cells contact non-GFP expressing muscle tissues that are presumably derived from the uninjured surrounding tissues. These cells are then integrated into the recovered muscle layers. We focus only on the implanted cells that maintained expression of GFP after implantation. At 7 days, the majority of both GFP and myoglobin, or SMA, or Pax7 double-positive cells are mononuclear. While we cannot definitively exclude the possibility of cellular fusion, the findings suggest that the number of these double-positive cells formed by cellular fusion is small.