3. Biodistribution of needle-injections and needle-free jet-injections visualized by a 3D- Fluorescent Imaging Cryomicrotome System 76 MATERIALS AND METHODS Collection procedures were in compliance with article 7:467 BW of the Dutch law. Formal approval for this exploratory ex vivo study from the Medical Ethics Board Committee (METC) was not required, because the tissue samples only involved anonymously collected material that was discarded following routine elective surgery. Study design In this exploratory study, the TCA biodistribution using different drug delivery techniques in ex vivo keloids and normal skin was investigated. TCA 40 mg/mL suspension (Kenacort, Bristol-Myers Squibb, New York City, New York, U.S.) was labeled with a fluorescent dye (Texas Red 10 µg/mL; 3000 MW, Invitrogen). TCA biodistribution was represented by the fluorescent TCA volume and 3D biodistribution shape of TCA, using a 3D-FluorescenceImaging Cryomicrotome System (3D-FICS). The drug delivery techniques were (1a) needle injection in the superficial, mid, and deep layer of the keloid; (1b) perforation technique, i.e. making multiple cross-sectional passes with a thick needle prior to injection in the mid-layer of the keloid; and (2) jet injection using pressures of 4, 5 and 6 Bar. For jet injections, the residual TCA volume on the keloid and skin was determined by wiping off the fluid on the surface of the keloid and skin using a gauze and measuring the weight increase of the gauze. Then, this residual weight was converted to residual volume using a conversion rate of 1.0496 (1 mL TCA = 0.9527 g, based on own measurements). Papule formation after each jet injection was directly captured using a 3D-camera (LifeViz Micro 600D, Quantificare, Sophia Antipolis, France). Study samples The selection of keloids was performed by two plastic surgeons (FN and OL) and one dermatologist (EP) experienced in keloid treatment. Keloids were included if a specimen of at least 1.5 x 1.5 cm could be harvested; regardless of the anatomic location, duration, etiology, and pretreatment. Keloids were excluded if (1) the differentiation between keloid and hypertrophic scar could not be made clinically, (2) the sample had been
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