Expression of the epidermal stem cell marker p63/CK5 in cutaneous papillomas and cutaneous squamous cell carcinomas of dogs

Cutaneous papillomas (CPs) and cutaneous squamous cell carcinomas (CSCCs) are usual epidermal tumours in dogs. CPs and CSCCs probably arise from the neoplastic transformation of the keratinocytes within the stem cell compartment, since these cells are the only keratinocytes that would reside long enough to accumulate the number of molecular alterations to drive the progression towards a tumour cell phenotype. However, the role of these cells in common epidermal tumours in dogs is still unknown. Thus, the purpose of this study was to evaluate the immunohistochemical expression pattern of p63 together with CK5, molecular markers of epidermal stem cells, on sections of tissue microarrays constructed from canine samples of CP and CSCC to investigate the contribution of stem cells in those canine tumours. p63/CK5 coexpression was retained in most basal and some suprabasal cells in CPs and CSCCs. In addition, increased coexpression of these molecules was observed in a group of CPs and CSCCs, as a result of a higher p63 expression. These results suggest that the coexpression of p63/CK5 may mark epidermal keratinocytes that possess self-renewal capacity rather than only stem cells, and suggest that transit amplifying cells, and even differentiated keratinocytes, may also contribute to the pathogenesis of epidermal tumours in dogs.

Microemulsion systems to enhance the transdermal permeation of ivermectin in dogs: A preliminary in vitro study

This study aims to evaluate the influence of the phase behavior of microemulsions in the transdermal administration ("spot-on") of ivermectin, an antiparasitic drug widely used in the treatment of endoparasites and ectoparasites in dogs. In this regard, pseudoternary phase diagrams composed of water (aqueous phase), isopropyl myristate (oil phase), tween 80 (surfactant) and labrasol (cosurfactant) were obtained in a different surfactant: cosurfactant (S:CS) ratios. S:CS in 1:3 ratio presented a larger region of microemulsion formation and three microemulsions were selected from it and characterized. Subsequently, in vitro permeation and retention studies were conducted using canine skin as membrane. SAXS, rheology and conductivity data were employed to confirm the phase behavior of the microemulsions (w/o, bicontinuous or o/w). The cutaneous permeation and retention tests showed that the w/o microemulsion, followed by bicontinuous microemulsion, resulted in a higher amount of drug permeated through canine skin, suggesting better transdermal permeation. On the other hand, o/w microemulsion resulted in a higher amount of drug accumulated into the skin, suggesting better topical activity. Thus, it can be concluded that phase behavior of microemulsions influenced the drug permeation in the canine skin differently from other animal models. Microemulsions, especially w/o and bicontinuous, can be promising vehicles regarding the transdermal delivery of ivermectin.

Use of flexible sensor to characterize biomechanics of canine skin

Background

Suture materials and techniques are frequently evaluated in ex vivo studies by comparing tensile strengths. However, the direct measurement techniques to obtain the tensile forces in canine skin are not available, and, therefore, the conditions suture lines undergo is unknown. A soft elastomeric capacitor is used to monitor deformation in the skin over time by sensing strain. This sensor was applied to a sample of canine skin to evaluate its capacity to sense strain in the sample while loaded in a dynamic material testing machine. The measured strain of the sensor was compared with the strain measured by the dynamic testing machine. The sample of skin was evaluated with and without the sensor adhered.

Results

In this study, the soft elastomeric capacitor was able to measure strain and a correlation was made to stress using a modified Kelvin-Voigt model for the canine skin sample. The sensor significantly increases the stiffness of canine skin when applied which required the derivation of mechanical models for interpretation of the results.

Conclusions

Flexible sensors can be applied to canine skin to investigate the inherent biomechanical properties. These sensors need to be lightweight and highly elastic to avoid interference with the stress across a suture line. The sensor studied here serves as a prototype for future sensor development and has demonstrated that a lightweight highly elastic sensor is needed to decrease the effect on the sensor/skin construct. Further studies are required for biomechanical characterization of canine skin.

Electronic supplementary material

The online version of this article (10.1186/s12917-018-1755-y) contains supplementary material, which is available to authorized users.