[Structural and biomechanical properties of accelular dermal matrix derived from human scar tissue]

To explore the structural and biomechanical properties of acellular dermal matrix (ADM) of human scar tissue.

Randomly choose 8 human mature scar tissue, 8 human hypertrophic scar tissue, and 4 normal human tissue as experimental samples respectively. Then 0.5 mm split-thickness skin grafts were obtained by drum-type scalpel, further acellularized by 2.5 g/L trypsin-0.5% TritonX-100. Structural analyses were performed by macroscopic observation, hematoxylin and eosin histological staining and scanning electron microscope. Then human epithelial stem cells were inoculated, cultured on those materials and observe their adhesive properties. Finally the biomechanical properties of ADM were analyzed through the detection of stress-strain relation, stress relaxation, creep and ultimate stress strength to distinguish different origins.

Prepared ADM was milky white in color despite their distinct origins, physiological and mature scar tissue derived ADM was soft and flexible in texture while ADM from hypertrophic scar showed a more tenacious character. Optical microscopic and electron microscopic analyses showed no sign of visible cellular structures. ADM from physiological group had relatively homogeneous and inerratic collagenous fibers, ADM from hypertrophic group presented with fibers of various diameters and arrayed in a compact and disordered manner. ADM from mature scar tissue possessed traits between the other two groups. Adhesion growth could be observed 2 weeks after inoculating human epithelial stem cells on ADM and cells grew in a cohesive fashion on ADM both from normal skin and mature scar tissue and in an adhesive fashion on hypertrophic scar tissue ADM. Stress-strain β value (3.024 ± 0.413, 2.595 ± 0.443, 2.590 ± 0.366), creep slope (0.018 ± 0.003, 0.019 ± 0.009, 0.023 ± 0.010) and ultimate stress strength (8.971 ± 2.434, 11.011 ± 1.492, 15.567 ± 2.931) of ADM showed no significant differences in hypertrophic scar, mature scar and normal skin tissues (all P > 0.05). ADM from mature scar and normal skin tissue showed no differences in stress-strain stretch ratio (0.238 ± 0.083 vs 0.291 ± 0.048), relaxation slope (-0.041 ± 0.009 vs -0.047 ± 0.008), total relaxation (0.775 ± 0.194 vs 0.968 ± 0.211) or total creep (0.033 ± 0.022 vs 0.049 ± 0.020) (all P > 0.05). However, the above related indices of ADM from hypertrophic scar tissue (0.188 ± 0.036, -0.033 ± 0.006, 0.481 ± 0.058, 0.020 ± 0.005) were significantly lower than those from normal tissue (all P < 0.05).

No significant differences exist between mature scar and normal skin tissues derived ADM both in structural and biomechanical properties. However ADM from mature scar appears to be superior in biomechanical properties than hypertrophic scar derived ADM so that it may become a replacement for original dermis in wound repair.