Sphere-enhanced microwave ablation (sMWA) versus bland microwave ablation (bMWA): technical parameters, specific CT 3D rendering and histopathology.

PURPOSE: This study was designed to compare technical parameters during ablation as well as CT 3D rendering and histopathology of the ablation zone between sphere-enhanced microwave ablation (sMWA) and bland microwave ablation (bMWA). METHODS: In six sheep-livers, 18 microwave ablations were performed with identical system presets (power output: 80 W, ablation time: 120 s). In three sheep, transarterial embolisation (TAE) was performed immediately before microwave ablation using spheres (diameter: 40 ± 10 µm) (sMWA). In the other three sheep, microwave ablation was performed without spheres embolisation (bMWA). Contrast-enhanced CT, sacrifice, and liver harvest followed immediately after microwave ablation. Study goals included technical parameters during ablation (resulting power output, ablation time), geometry of the ablation zone applying specific CT 3D rendering with a software prototype (short axis of the ablation zone, volume of the largest aligned ablation sphere within the ablation zone), and histopathology (hematoxylin-eosin, Masson Goldner and TUNEL). RESULTS: Resulting power output/ablation times were 78.7 ± 1.0 W/120 ± 0.0 s for bMWA and 78.4 ± 1.0 W/120 ± 0.0 s for sMWA (n.s., respectively). Short axis/volume were 23.7 ± 3.7 mm/7.0 ± 2.4 cm(3) for bMWA and 29.1 ± 3.4 mm/11.5 ± 3.9 cm(3) for sMWA (P < 0.01, respectively). Histopathology confirmed the signs of coagulation necrosis as well as early and irreversible cell death for bMWA and sMWA. For sMWA, spheres were detected within, at the rim, and outside of the ablation zone without conspicuous features. CONCLUSIONS: Specific CT 3D rendering identifies a larger ablation zone for sMWA compared with bMWA. The histopathological signs and the detectable amount of cell death are comparable for both groups. When comparing sMWA with bMWA, TAE has no effect on the technical parameters during ablation.

Intracutaneously injected human adipose tissue-derived stem cells in a mouse model stay at the site of injection.

The aim of this study was to evaluate the local behavior of intracutaneously injected human mesenchymal stem cells from adipose tissue and to determine the safety of a cell-based cutaneous therapy in an animal model.Human mesenchymal stem cells from adipose tissue were labeled with red fluorochrome and were injected intradermally in the paravertebral area in immunodeficient BalbC/nude mice (n = 21). As a control, cell culturemedium was injected in the same fashion on the contralateral paravertebral side. Four weeks, 6 months, and 12 months after the injection, seven mice were examined. In addition to the injected areas, the lungs, kidneys,spleens, and brains were excised and processed for histological evaluation. Serial sections of all the tissues excised were evaluated for adipose tissue-derived stem cells by means of emerging red fluorescent signals.The injected stem cells could be detected throughout the follow-up period of 1-year at the injection site within the dermal and subcutaneous layers. Bar these areas, adipose tissue-derived stem cells were not found in any otherexamined tissue at any point in time. The adipose tissue-derived stem cells showed a slow transition to deeper subcutaneous adipose tissue layers and, in part, a differentiation into adipocytes. No ulceration, inflammation, ortumor induction could be detected.The present study shows that intracutaneously injected human mesenchymal stem cells from adipose tissue stay at the site of injection, survive in vivo for up to 1-year, and partly differentiate into adipocytes. This is a new andvery important finding needed to safely apply therapies based on such stem cells in fat transplants in regenerative medicine.