Semi-occlusive management of fingertip injuries with finger caps: A randomized controlled trial in children and adults.

BACKGROUND: Human fingertips can regenerate functionally and cosmetically excellent skin and soft tissues. Physiological conditions suppress scar formation and are thus a prerequisite for regenerative healing. Self-adhesive film dressings can provide such favorable conditions. The semi-occlusive treatment is superior to surgery. However, standard dressings leak malodorous wound fluid eventually until the wound is dry. Therefore, we developed and tested a silicone finger cap that forms a mechanically protected, wet chamber around the injury. Its puncturable reservoir allows access to the wound fluid for diagnostic and research purposes and the delivery of pro-regenerative drugs in the future. METHODS: Patients >2 years with full-thickness fingertip injuries unsuitable for simple primary closure were randomized to start treatment with either the film dressing or the silicone finger cap. After 2 weeks, we changed to the other treatment. Patients' choice on the preferred treatment after 4 weeks was the primary outcome parameter. Additionally, we monitored adverse events, unplanned visits, tissue gain, functionality, cosmetic outcome, and quality of life. RESULTS: We randomized 11 patients 2 to 72 years to each group. Eighteen to 20 (90%, intention-to-treat) patients preferred the finger cap. All patients were satisfied with the cosmetic outcome, 88.9% had no disturbing sensibility changes, and 73.7% could report no distortion in the finger's daily use. Epithelialization took between 5 weeks for Allen II and up to 9 weeks in Allen IV injuries. There were 19 device-related adverse events under film dressing and 13 under the finger cap. There were neither severe adverse device effects nor unexpected severe adverse device effects. CONCLUSION: Employing the summative or synthetic primary endpoint "patient decision for one or the other procedure," our pseudocross-over-designed RCT succeeded in statistically significantly demonstrating the superiority of the silicone finger cap over conventional film therapy. The finger cap was safe and effective, reaching excellent results on all treated injuries without any need for disinfection, antibiotics, shortening of protruding bones, or treatment of hypergranulations. Distal to the tendon insertions, we did not see any limitations regarding injury mechanism, amputation plane, or patients' age.

Study protocol for a randomized controlled pilot-trial on the semiocclusive treatment of fingertip amputation injuries using a novel finger cap.

INTRODUCTION: Fingertip amputation injuries are common in all ages. Conservatively treated fingertips can regenerate skin and soft tissues to form a functionally and cosmetically excellent new fingertip. Little is known about this ability that, in humans, is confined to the fingertips. Even less is known about the role of the bacteria that regularly colonize these wounds without negative impact on regeneration and healing.As an alternative to surgery, self-adhesive film dressings are commonly used to establish a wet chamber around the injury. These dressings leak malodorous wound fluid eventually until the wound is dry. Having that into consideration, we have therefore developed a silicone finger cap that forms a mechanically protected, wet chamber around the injury for optimal regeneration conditions. It contains a puncturable reservoir for excess wound fluid, which can be thus routinely analyzed for diagnostic and research purposes.This study protocol explains the first randomized controlled trial (RCT) on the semiocclusive treatment of fingertip amputations in both children and adults comparing traditional film dressings with the novel silicone finger cap. Being the first RCT using 2 medical devices not yet certified for this indication, it will gather valuable information for the understanding of fingertip regeneration and the design of future definitive studies. METHODS AND ANALYSIS: By employing an innovative pseudo-cross-over-design with a dichotomous primary endpoint based on patients preference, this pilot study will gain statistically significant data with a very limited sample size. Our RCT will investigate acceptance, safety, effectiveness, and efficacy of this novel medical device while gathering information on the clinical course and outcome of conservatively treated fingertip injuries. A total of 22 patients older than 2 years will be randomly assigned to start the conservative treatment with either the traditional film-dressing or the novel finger cap. The treatment will be changed to the other alternative for another 2 weeks before the patient or the guardian is confronted with the decision of which method they would prefer for the rest of the treatment (if required). ETHICS AND DISSEMINATION: Ethical approval (EK 148042015) of the study protocol has been obtained from Institutional Review Board at the TU Dresden. The trial is registered at the European Database on Medical Devices (EUDAMED-No.: CIV-15-03-013246) and at ClinicalTrials.gov (NCT03089060).

Xenobiotic metabolism capacities of human skin in comparison with a 3D epidermis model and keratinocyte-based cell culture as in vitro alternatives for chemical testing: activating enzymes (Phase I).

Skin is important for the absorption and metabolism of exposed chemicals such as cosmetics or pharmaceuticals. The Seventh Amendment to the EU Cosmetics Directive prohibits the use of animals for cosmetic testing for certain endpoints, such as genotoxicity; therefore, there is an urgent need to understand the xenobiotic metabolizing capacities of human skin and to compare these activities with reconstructed 3D skin models developed to replace animal testing. We have measured Phase I enzyme activities of cytochrome P450 (CYP) and cyclooxygenase (COX) in ex vivo human skin, the 3D skin model EpiDerm™ (EPI-200), immortalized keratinocyte-based cell lines and primary normal human epidermal keratinocytes. Our data demonstrate that basal CYP enzyme activities are very low in whole human skin and EPI-200 as well as keratinocytes. In addition, activities in monolayer cells differed from organotypic tissues after induction. COX activity was similar in skin, EPI-200 and NHEK cells, but was significantly lower in immortalized keratinocytes. Hence, the 3D model EPI-200 might represent a more suitable model for dermatotoxicological studies. Altogether, these data help to better understand skin metabolism and expand the knowledge of in vitro alternatives used for dermatotoxicity testing.

Xenobiotic metabolism capacities of human skin in comparison with a 3D-epidermis model and keratinocyte-based cell culture as in vitro alternatives for chemical testing: phase II enzymes.

The 7th Amendment to the EU Cosmetics Directive prohibits the use of animals in cosmetic testing for certain endpoints, such as genotoxicity. Therefore, skin in vitro models have to replace chemical testing in vivo. However, the metabolic competence neither of human skin nor of alternative in vitro models has so far been fully characterized, although skin is the first-pass organ for accidentally or purposely (cosmetics and pharmaceuticals) applied chemicals. Thus, there is an urgent need to understand the xenobiotic-metabolizing capacities of human skin and to compare these activities to models developed to replace animal testing. We have measured the activity of the phase II enzymes glutathione S-transferase, UDP-glucuronosyltransferase and N-acetyltransferase in ex vivo human skin, the 3D epidermal model EpiDerm 200 (EPI-200), immortalized keratinocyte-based cell lines (HaCaT and NCTC 2544) and primary normal human epidermal keratinocytes. We show that all three phase II enzymes are present and highly active in skin as compared to phase I. Human skin, therefore, represents a more detoxifying than activating organ. This work systematically compares the activities of three important phase II enzymes in four different in vitro models directly to human skin. We conclude from our studies that 3D epidermal models, like the EPI-200 employed here, are superior over monolayer cultures in mimicking human skin xenobiotic metabolism and thus better suited for dermatotoxicity testing.