Native human dermis versus human acellular dermal matrix: A comparison of biaxial mechanical properties

Background Human Acellular Dermal Matrices (HADMs), thanks to its mechanical resistance and it’s not immunogenic response, is used in reconstructive surgery such as breast reconstruction procedures and hernia repairs. There is the need to investigate the mechanical response of HADMs when subjected to in vivo-like stresses. Aims In order to supply additional guidance to surgeons, in this work equi-biaxial experimental curves of native and decellularized human dermis are presented because it is essential to investigate the engineered tissue response when subjected to stresses comparable to those that occur in vivo. Methods HADMs specimens were biaxially characterized exploiting a customized biaxial conversion device entirely realized through rapid prototyping methods, and the HADM response to mechanical stimuli comparable to the in vivo deformation state was explored. From the derived data, stress-strain curves were evaluated, and the elastic moduli were extracted from the curve toe-region. As an indication of the fibre rearrangement rate, the slope of the stressstrain curve at higher strains was evaluated in a semi-log plane. Results The mean elastic modulus at low strains for the mediolateral direction (along Langer lines) resulted from 35 per cent to 87 per cent higher than the cranio-caudal one. Furthermore, medio-lateral specimens show lower rearrangement velocities at higher strains. Considering both directions, the decellularization process leads to a deterioration of the mechanical properties of the matrix. Conclusion The tested HADMs maintained the typical anisotropic dermis behaviour, dependent on the collagen network predominantly oriented along the Langer lines. Moreover, comparisons among HADMs and the native human reticular dermis demonstrated the mechanical strength loss at lower strains caused by the decellularization process.