Endoscopic repair of the urinary bladder with magnetically labeled mesenchymal stem cells: Preliminary report

Transurethral resection of a bladder tumor (TURBT) using a resectoscope has been standard treatment for bladder cancer. However, no treatment method promotes the repair of resected bladder tissue. The aim of this study was to examine the healing process of damaged bladder tissue after a transurethral injection of bone marrow mesenchymal stem cells (MSCs) into the bladder. An injection of magnetic MSCs meant that they accumulated in the damaged area of the bladder. Another aim of this study was to compare the acceleration effect of MSC magnetic delivery on the repair of bladder tissue with that of non-magnetic MSC injection.

Using the transurethral approach to avoid opening the abdomen, electrofulguration was carried out on the anterior wall of the urinary bladder of white Japanese rabbits to mimic tumor resection. An external magnetic field directed at the injured site was then applied using a 1-tesla (T) permanent magnet. Twelve rabbits were divided into three groups. The 1 × 10⁶ of magnetically labeled MSCs were injected into the urinary bladder with or without the magnetic field (MSC M+ and MSC M-groups, respectively), and phosphate-buffered saline was injected as the control. The effects of the injections in the three groups at 14 days were examined using 4.7-T magnetic resonance imaging (MRI) then macroscopically and histologically. The mRNA expressions of several cytokines in the repair tissues were assessed using real-time polymerase chain reaction.

The macroscopic findings showed the area of repair tissue in the MSC M+ group to be larger than that in either the MSC M-group or control group. MRI clearly depicted the macroscopic findings. The histological study showed that repair of the cauterized area with myofibrous tissue was significantly better in the MSC M+ group than that in either the MSC M-group or control group, although there was no significant difference in several mRNA cytokines among the three groups at 14 days after surgery.

The magnetic delivery of MSCs shows promise as an effective, minimally invasive method of enhancing tissue regeneration after TURBT.