Silkworm Silk Scaffolds Functionalized with Recombinant Spider Silk Containing a Fibronectin Motif Promotes Healing of Full-Thickness Burn Wounds

Abstract

Full-thickness cutaneous wounds, such as deep burns, are complex wounds that often require surgical interventions. Herein, we show the efficacy of acellular grafts that can be made available off-theshelf at an affordable cost using silk biomaterials. Silkworm silk fibroin (SF), being a cost-effective and natural biopolymer, provides essential features required for the fabrication of three-dimensional constructs for wound-healing applications. We report the treatment of third-degree burn wounds using a freeze-dried microporous scaffold of Antheraea assama SF (AaSF) functionalized with a recombinant spider silk fusion protein FN-4RepCT (FN-4RC) that holds the fibronectin cell binding motif. In order to examine the healing efficiency of functionalized silk scaffolds, an in vivo burn rat model was used, and the scaffolds were implanted by a one-step grafting procedure. The aim of our work is to investigate the efficacy of the developed acellular silk grafts for treating full-thickness wounds as well as to examine the effect of recombinant spider silk coatings on the healing outcomes. Following 14-day treatment, AaSF scaffolds coated with FN-4RC demonstrated accelerated wound healing when compared to the uncoated counterpart, commercially used DuoDERM dressing patch, and untreated wounds. Histological assessments of wounds over time further confirmed that functionalized silk scaffolds promoted wound healing, showing vascularization and re-epithelialization in the initial phase. In addition, higher extent of tissue remodeling was affirmed by the gene expression study of collagen type I and type III, indicating advanced stage of healing by the silk treatments. Thus, the present study validates the potential of scaffolds of combined silkworm silk and FN-4RC for skin regeneration.

Emerging Functional Biomaterials as Medical Patches

“…Moreover, wound healing effects were evaluated in murine models for up to 28 days and the patch showed the fastest wound healing effect and resulted in a smooth epidermal layer compared with the other two groups (Figure A,ii). Meanwhile, Mandal et al designed a freeze-dried microporous fibronectin motif (FN-4RC)-coated spider silk scaffold for dealing with third-degree deep burns . It was demonstrated that in contrast to the uncoated counterpart, the scaffold displayed high wound closure efficiency in an in vivo rat burn model within 14-day treatment benefiting from the biological activity of the spider silk fusion protein in the scaffold, as shown in Figure B.…”

“…(B) Re-epithelialization assessment of wounds on days 14 and 21 by IHC assay for a freeze-dried microporous FN-4RC-coated spider silk scaffold. Reprinted with permission from ref . Copyright 2019 American Chemical Society.…”

Harnessing Multifaceted Next-Generation Technologies for Improved Skin Wound Healing

“…112 Similarly, further progress was achieved by adding endothelial cells (ECs) along with fibroblasts, which generated prevascularized skin grafts in a facile manner. 63,113 Further advancement in this field can be seen in stem cell 114−116 The advantages and disadvantages of the application of these stem cells as therapeutics are enlisted in Table 2. In a recent report, a well-established dermal graft, Integra, was used to culture human SGSCs that demonstrated enhanced vascularization in the regenerated dermal region.…”

Insight into Silk-Based Biomaterials: From Physicochemical Attributes to Recent Biomedical Applications

“…Silk, known for incisional wound healing in the form of silk sutures, has been found to trigger cell proliferation and cell migration via NF-KB signaling pathway in a recent study . The wound healing property of silk has been examined in various formats such as nanofibrous mats, thin films, hydrogels, and porous scaffolds, which have shown better healing properties in comparison to the commercially available products. , Electrospun silk nanofibrous nonwoven membranes showed a significant effect on cell attachment and spreading in vitro for normal human fibroblasts and keratinocytes . In further studies, three different forms of silk matrices, woven (microfiber), nonwoven (nanofiber), and regenerated film were utilized to perform a conformational analysis and cell culture using normal human oral keratinocytes (NHOK) .…”