Skin Tissue Engineering Advances in Burns: A Brief Introduction to the Past, the Present, and the Future Potential

Cotton cellulose nanofiber/chitosan scaffolds for skin tissue engineering and wound healing applications

Chitosan (CS) is a promising polymeric biomaterial for use in scaffolds forin vitroskin models and wound dressings, owing to its non-antigenic and antimicrobial properties. However, CS often exhibits insufficient physicochemical properties, mechanical strength, and bioactivity, limiting its efficacy in demanding applications. To address these challenges, cotton cellulose nanofibers (CNFs) represent a promising nanomaterial for enhancing CS-based scaffolds in tissue engineering. CNF offers superior stiffness, and mechanical properties that enhance cellular adhesion and proliferation, both crucial for effective tissue regeneration and healing. This study aimed to develop and characterize a scaffold combining cotton CNF and CS, focusing on its cytocompatibility with human fibroblasts and keratinocytes. The cotton CNF/CS scaffold was fabricated using the casting technique, and its physicochemical properties and cellular compatibility were assessedin vitro. The results demonstrated that incorporating cotton CNF significantly enhanced the stability of the CS matrix. The CS scaffold with 1000 μg ml-1of cotton CNF exhibited increased roughness and reduced rupture strain compared to the pure CS scaffold. The cotton CNF/CS scaffold effectively promoted the adhesion, viability, proliferation, migration, and collagen synthesis of skin cells. Notably, increased cell viability was observed in human fibroblasts cultured on scaffolds with higher concentrations of cotton CNF (100 and 1000 μg ml-1). Based on the findings, the cotton CNF/CS scaffold demonstrates enhanced physicochemical properties and bioactivity, making it a promising candidate for the development ofin vitrohuman skin models and wound healing dressings.

The added value of cultured cells in burn treatment: A systematic review

INTRODUCTION

Advancements in resuscitative care and burn surgery have improved survival rates after extensive burn injuries, shifting focus to enhancing the quality of survival. Conventional treatment with split-thickness skin grafts (STSG) presents limitations such as donor-site morbidity, limited availability in extensive burn injuries, and hypertrophic scarring. Tissue engineering aims to address these drawbacks by developing optimal skin substitutes. This systematic review aims to provide an overview of the current applications of cultured cells in burn surgery, encompassing diverse approaches and addressing existing challenges to enhance burn wound management and improve patient outcomes.

METHODS

Following PRISMA guidelines, a comprehensive search was performed across three databases (PubMed, Embase, Cochrane Library) for articles on cultured cell use in burn treatment. Only clinical studies were included. Articles were screened by two independent reviewers. Quality assessment was performed.

RESULTS

The search yielded 167 articles, of which 14 met the eligibility criteria. The selection included 8 randomized controlled trials, 5 prospective cohort trials, and 1 retrospective cohort study. Various tissue-engineered skin substitutes, from cultured epidermal autografts to dermal regeneration templates seeded with cultured cells, showed promising outcomes. Several substitutes exhibited take rates comparable to STSG with improved scar quality.

CONCLUSION

Results are promising, though standardization of cultured skin substitutes and robust clinical trials with larger populations and appropriate comparators are still lacking.

Emerging Technologies

In this article, an array of new developments in burn care, from diagnosis to post-burn reconstruction and re-integration, will be discussed. Multidisciplinary advances have allowed the implementation of technologies that provide more accurate assessments of burn depth, improved outcomes when treating full-thickness burns, and enhanced scar tissue management. Incorporating these new treatment modalities into current practice is essential to improving the standard of burn care and developing the next generation of burn wound management methodologies.

Functionalization of Ceramic Scaffolds with Exosomes from Bone Marrow Mesenchymal Stromal Cells for Bone Tissue Engineering

The functionalization of bone substitutes with exosomes appears to be a promising technique to enhance bone tissue formation. This study investigates the potential of exosomes derived from bone marrow mesenchymal stromal cells (BMSCs) to improve bone healing and bone augmentation when incorporated into wide open-porous 3D-printed ceramic Gyroid scaffolds. We demonstrated the multipotent characteristics of BMSCs and characterized the extracted exosomes using nanoparticle tracking analysis and proteomic profiling. Through cell culture experimentation, we demonstrated that BMSC-derived exosomes possess the ability to attract cells and significantly facilitate their differentiation into the osteogenic lineage. Furthermore, we observed that scaffold architecture influences exosome release kinetics, with Gyroid scaffolds exhibiting slower release rates compared to Lattice scaffolds. Nevertheless, in vivo implantation did not show increased bone ingrowth in scaffolds loaded with exosomes, suggesting that the scaffold microarchitecture and material were already optimized for osteoconduction and bone augmentation. These findings highlight the lack of understanding about the optimal delivery of exosomes for osteoconduction and bone augmentation by advanced ceramic scaffolds.

Current Biomaterials for Wound Healing

Wound healing is the body's process of injury recovery. Skin healing is divided into four distinct overlapping phases: hemostasis, inflammation, proliferation, and remodeling. Cell-to-cell interactions mediated by both cytokines and chemokines are imperative for the transition between these phases. Patients can face difficulties in the healing process due to the wound being too large, decreased vascularization, infection, or additional burdens of a systemic illness. The field of tissue engineering has been investigating biomaterials as an alternative for skin regeneration. Biomaterials used for wound healing may be natural, synthetic, or a combination of both. Once a specific biomaterial is selected, it acts as a scaffold for skin regeneration. When the scaffold is applied to a wound, it allows for the upregulation of distinct molecular signaling pathways important for skin repair. Although tissue engineering has made great progress, more research is needed in order to support the use of biomaterials for wound healing for clinical translation.

Scars

Wound healing occurs as a response to disruption of the epidermis and dermis. It is an intricate and well-orchestrated response with the goal to restore skin integrity and function. However, in hundreds of millions of patients, skin wound healing results in abnormal scarring, including keloid lesions or hypertrophic scarring. Although the underlying mechanisms of hypertrophic scars and keloid lesions are not well defined, evidence suggests that the changes in the extracellular matrix are perpetuated by ongoing inflammation in susceptible individuals, resulting in a fibrotic phenotype. The lesions then become established, with ongoing deposition of excess disordered collagen. Not only can abnormal scarring be debilitating and painful, it can also cause functional impairment and profound changes in appearance, thereby substantially affecting patients' lives. Despite the vast demand on patient health and the medical society, very little progress has been made in the care of patients with abnormal scarring. To improve the outcome of pathological scarring, standardized and innovative approaches are required.

Living Skin Substitute Tissue-Is a Replacement for the Autograft Possible?

The ideal living tissue skin substitute for use in burn injury does not yet exist. The currently available alternatives to autologous skin grafting require an understanding of their characteristics and limitations to make an informed decision of surgical treatment options. In this review, living tissue substitutes are categorized by autologous and allogeneic cell sources and epidermal-only versus bilayered tissue options. A short summary of the tissue composition, clinical data, and indications is provided. Finally, the gap in technology is defined and future potential areas of research are explored.

The rise of mechanical metamaterials: Auxetic constructs for skin wound healing

Auxetic materials are known for their unique ability to expand/contract in multiple directions when stretched/compressed. In other words, they exhibit a negative Poisson's ratio, which is usually positive for most of materials. This behavior appears in some biological tissues such as human skin, where it promotes wound healing by providing an enhanced mechanical support and facilitating cell migration. Skin tissue engineering has been a growing research topic in recent years, largely thanks to the rapid development of 3D printing techniques and technologies. The combination of computational studies with rapid manufacturing and tailored designs presents a huge potential for the future of personalized medicine. Overall, this review article provides a comprehensive overview of the current state of research on auxetic constructs for skin healing applications, highlighting the potential of auxetics as a promising treatment option for skin wounds. The article also identifies gaps in the current knowledge and suggests areas for future research. In particular, we discuss the designs, materials, manufacturing techniques, and also the computational and experimental studies on this topic.