A micromechanical comparison of human and porcine skin before and after preservation by freezing for medical device development.

S A Ranamukhaarachchi,S L Ranamukhaarachchi,L Sprenger,K Rai,T Schneider,B Stoeber,U O Häfeli,S Lehnert,I Mansoor

doi:10.1038/srep32074

S A Ranamukhaarachchi, S L Ranamukhaarachchi + Show 7 more

Open Access

https://doi.org/10.1038/srep32074

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Journal: Scientific reports	Publication Date: Aug 1, 2016
Citations: 122	License type: CC BY 4.0

Affiliation: TU Dresden, University of British Columbia

Abstract

Collecting human skin samples for medical research, including developing microneedle-based medical devices, is challenging and time-consuming. Researchers rely on human skin substitutes and skin preservation techniques, such as freezing, to overcome the lack of skin availability. Porcine skin is considered the best substitute to human skin, but their mechanical resemblance has not been fully validated. We provide a direct mechanical comparison between human and porcine skin samples using a conventional mechano-analytical technique (microindentation) and a medical application (microneedle insertion), at 35% and 100% relative humidity. Human and porcine skin samples were tested immediately after surgical excision from subjects, and after one freeze-thaw cycle at −80 °C to assess the impact of freezing on their mechanical properties. The mechanical properties of fresh human and porcine skin (especially of the stratum corneum) were found to be different for bulk measurements using microindentation; and both types of skin were mechanically affected by freezing. Localized in-plane mechanical properties of skin during microneedle insertion appeared to be more comparable between human and porcine skin samples than their bulk out-of-plane mechanical properties. The results from this study serve as a reference for future mechanical tests conducted with frozen human skin and/or porcine skin as a human skin substitute.

Highlights

That porcine skin would have similar mechanical properties to human skin
Skin samples were distinguished by source, state, and the relative humidity (RH) condition used during testing and analysis
This study aimed to show, for the first time, a direct comparison of the mechanical properties of human and porcine skin before and after freezing, demonstrating the impact of freezing on mechanical changes that occur in skin, such as decreasing stiffness and increasing total energy required to break the stratum corneum

Summary

Introduction

That porcine skin would have similar mechanical properties to human skin. Many studies used porcine skin as a substitution for human skin[15,16,17] without confirming the mechanical similarities of both skin types in controlled experiments. The mechanical properties of human and porcine skin changed differently when humidity increased from dry to wet conditions, which might have occurred due to structural differences between the two skin types. The objectives of the present study were to provide a direct mechanical comparison between human and porcine skin to test the assumptions of mechanical similarity between the two skin types; and to assess the impact of freezing the skin on its mechanical properties. This mechanical comparison between human and porcine skin will serve as a reference for mechanical studies involving the two skin types, and assist in identifying the conditions where human skin can be simulated using porcine skin

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Conclusion