In vivo imaging of adipose-derived stem cell sheets on biodegradable nonwoven fabric using X-ray CT.

Background: A biodegradable nonwoven fabric that can be used to extract adipose-derived stem cells (ADSCs) from adipose tissue slices was developed, which were cultured rapidly without enzymatic treatment. The extracted and cultured ADSCs remain on the nonwoven fabric and form a thick cell sheet. The aim was to use the thick cell sheet as a treatment by transplanting it into the living body. In addition, the expectation was that it will be possible to observe the cell sheet in the living body using X-ray computed tomography (CT) because the nonwoven fabric used to produce the cell sheet contains 50% (by weight) hydroxyapatite.

Results: Thick cell sheets of ADSCs supported by two layers of nonwoven fabric were cut to size and transplanted into the cheeks of rats. No health damage was observed in the rats in which the cell sheets were implanted, except for one in which the surgery appeared to have failed. X-ray CT imaging showed that the fabric of the implanted cell sheet biodegraded over 12 weeks. Changes in the position, shape, and size of the cell sheet within the rat's body were tracked by X-ray CT. The thick cell sheets, which can be easily produced by simply seeding tissue slices, can be cut into appropriate shapes and transplanted safely, and it was confirmed that they slowly biodegraded when transplanted into the rats' bodies.

Conclusions: We demonstrated not only that the thick ADSC sheets can be transplanted successfully into animals, but also that the transplanted sheets can be observed in vivo by X-ray CT, which also allows changes in the ADSC sheets to be tracked. The results suggest that the biodegradable nonwoven fabric will be a useful transplantation device to ensure cell engraftment throughout the affected area, and facilitate monitoring of the transplant's subsequent status. We expect that this transplantation device will promote the development of regenerative therapy.