Skin Tissue Engineering for the Infected Wound Site: Biodegradable PLA Nanofibers and a Novel Approach for Silver Ion Release Evaluated in a 3D Coculture System of Keratinocytes and Staphylococcus aureus

Abstract

Wound infection presents a challenging and growing problem. With the increased prevalence and growth of multidrug-resistant bacteria, there is a mounting need to reduce and eliminate wound infections using methodologies that limit the ability of bacteria to evolve into further drug-resistant strains. A well-known strategy for combating bacterial infection and preventing wound sepsis is through the delivery of silver ions to the wound site. High surface area silver nanoparticles (AgNPs) allowing extensive silver ion release have therefore been explored in different wound dressings and/or skin substitutes. However, it has been recently shown that AgNPs can penetrate into the stratum corneum of skin or diffuse into the cellular plasma membrane, and may interfere with a variety of cellular mechanisms. The goal of this study was to introduce and evaluate a new type of high surface area metallic silver in the form of highly porous silver microparticles (AgMPs). Polylactic acid (PLA) nanofibers were successfully loaded with either highly porous AgMPs or AgNPs and the antimicrobial efficacy and cytotoxicity of the two silver-based wound dressings were assessed and compared. To better mimic the physiological environment in vivo where both human cells and bacteria are present, a novel coculture system combining human epidermal keratinocytes and Staphylococcus aureus bacteria was designed to simultaneously evaluate human skin cell cytotoxicity with antimicrobial efficacy in a three-dimensional environment. We found that highly porous AgMPs could be successfully incorporated in nanofibrous wound dressings, and exhibited comparable antimicrobial efficacy and cytotoxicity to AgNPs. Further, PLA nanofibers containing highly porous AgMPs exhibited steady silver ion release, at a greater rate of release, than nanofibers containing AgNPs. The replacement of AgNPs with the newly introduced AgMPs overcomes concerns regarding the use of nanoparticles and holds great promise as skin substitutes or wound dressings for infected wound sites.

Fabrication of polydopamine nanoparticles knotted alginate scaffolds and their properties

“…The scaffolds are generally required to degrade after the new tissues growth, achieving a best curative effect for cellular activities …”

“…The scaffolds are generally required to degrade after the new tissues growth, achieving a best curative effect for cellular activities. 42 . Thus, degradability of the scaffolds is very important index for the implant materials.…”

Electrospun nanofibrous scaffolds increase the efficacy of stem cell-mediated therapy of surgically resected glioblastoma

“…PLA scaffolds were developed as previously described [22,23]. Briefly, PLA (MW = 70,000) was dissolved in chloroform and dimethylformamide (3:1) (Sigma) at 80 °C to create a 11 wt% solution.…”

Poly(lactic acid) nanofibrous scaffolds for tissue engineering

“…While the ideal cutaneous wound dressing would prevent and/or treat infection in conjunction with improving healing, resolution of infection is a minimum requirement for any further therapies to succeed and thus this type of therapy remains useful for cutaneous wound healing. PLA nanofibrous wound dressings have also been doped with silver microparticles and nanoparticles to evaluate the composite mesh as an antibacterial wound dressing [76]. When evaluated in a 3-dimensional co-culture of keratinocytes and S. aureus , silver was shown to decrease both S. aureus and keratinocyte proliferation [76].…”

“…PLA nanofibrous wound dressings have also been doped with silver microparticles and nanoparticles to evaluate the composite mesh as an antibacterial wound dressing [76]. When evaluated in a 3-dimensional co-culture of keratinocytes and S. aureus , silver was shown to decrease both S. aureus and keratinocyte proliferation [76]. Interestingly, the cell-seeded wound dressings inhibited bacterial growth as much as the presence of silver particles, indicating that a scaffold that is more conducive to cell growth will be more resistant to S. aureus infection [76].…”