Fig. 7.

Exemparily histology of BPCM-based tissue regeneration of small-sized skin defects. a Overview of the implant area of CM (double arrows), which was placed above the subepidermal connective tissue (CT). Tissue ingrowth was seen at the spongy matrix layer (blue asterisks) adjacent to the wound base, while the upper compact layer was covered by regenerated epidermis (EP) (Sirius-staining, 100× magnification, scale bar =100 μm). b The spongy matrix layer was invaded only by single mononuclear cells (black arrows) and this matrix layer was directly contiguous to the regenerated epidermis (EP, double arrow) (Azan-staining, 200× magnification, scale bar =100 μm). c The epidermal layer (EP) covering the compact matrix layer (BPCM) showed a multi-layered cellular structure including a basal cell layer (blue arrows), the Stratum granulosum/spinosum (black asterisks) and the Stratum corneum (red arrows) (Sirius-staining, 200× magnification, scale bar =100 μm). d The outer region of the spongy layer of the BPCM covering the wound base (connective tissue, CT) was invaded by connective tissue matrix (green asterisks) and mononuclear cells (black arrows), while the central region was not integrated at this time point (Sirius-staining, 200× magnification, scale bar =100 μm). e and f The mononuclear cells that have invaded both the compact e and the spongy f matrix layers of the BPCM were identified mainly as macrophages (purple arrows). The immunohistochemical detection also showed the presence of cells of macrophage lineage within the covering epidermal layer (EP), indicating the complete regeneration of this tissue (CD68 immunohistochemical staining, 200× magnification, scale bars =100 μm). g and h The detection of TRAP showed that only a minority of the mononuclear cells that invaded the compact g and the spongy h layers of the BPCM showed signs of expression (TRAP immunohistochemistry, 200× magnification, scale bars =100 μm)