Diabetic Wound healing using a synthetic bilayer scaffold

Treatment of full-thickness skin wounds with minimal scarring and complete restoration of native tissue properties still exists as a clinical challenge. We fabricated a bilayer skin substitute by coating human amniotic membrane with an electrospun nanofibrous silk fibroin layer to improve mechanical properties of the amniotic membrane (AM). Since this bilayer scaffold exhibited improved mechanical properties, surface hydrophilicity, and in vitro biocompatibility, in vivo biological behavior of this scaffold was investigated in murine full-thickness skin wound model. Donut-shaped silicon splints were utilized to prevent wound contraction in mouse skin and simulate re-epithelialization, which is the normal path of human wound healing. The skin regeneration using bilayer scaffold was compared with AM and untreated defect after 30 days. Tissue samples were taken from healed wound areas and studied by means of histopathological evaluation and immunohistochemical staining, to visualize involucrin (IVL), P63, Collagen I, CD31, and VEGF. In addition, mRNA expression of IVL, P63, interleukin-6 (IL-6) and cyclooxygenase-2 (COX-2) was studied. Based on the obtained data, the application of bilayer scaffold resulted in the best epidermal and dermal regeneration, demonstrated by histopathological examination and molecular analyses. The mRNA expression levels of inflammatory markers (IL-6 and COX-2) in regenerative tissues by bilayer scaffold were down-regulated and expression pattern of keratinocyte markers including IVL and P63 markers at both mRNA and protein levels in bilayer scaffold group was more similar to native tissue in comparison to AM and no-treatment groups. There was no significant difference in expression level of Collagen I, CD31, and VEGF among different groups. Based on animal study results, preliminary evaluation of wound healing using this construct was done in 10 patients with foot ulcer after signing informed consent. The data showed safety and efficacy of the scaffold as well as wound area was significantly decreased from the beginning of treatment to the end of the first four weeks. Studies done in different phases were approved by Medical Ethic Committee of Avicenna Research institute (ACECR, Tehran, Iran) and registrated in Iranian Registry of Clinical Trials. Conclusively, these promising results suggest that this bilayer scaffold can represent a potential substitute for skin regeneration application and serve as supporting evidence for proceeding to major clinical phase.

Keywords:

Skin tissue engineering , Bilayer scaffold , Human amniotic membrane , Silk fibroin , Wound healing