Evolution of Biological Bandages as First Cover for Burn Patients

Abstract

Significance: Cutaneous wound regeneration is vital to keep skin functions and for large wounds, to maintain human survival. In a deep burn, the ability of the skin to heal is compromised due to the damage of vasculature and resident cells, hindering a coordinated response in the regeneration process. Temporal skin substitutes used as first cover can play a major role in skin regeneration as they allow a rapid wound covering that, in turn, can significantly reduce infection risk, rate of secondary corrective surgeries, and indirectly hospitalization time and costs. Recent Advances: Skin was one of the first tissues to be bioengineered providing thus a skin equivalent; however, what is the current status subsequent to 40 years of tissue engineering? We review the classic paradigms of biological skin substitutes used as first cover and evaluate recent discoveries and clinical approaches adapted for burn injuries cover, with an emphasis on innovative cell-based approaches. Critical Issues: Cell-based first covers offer promising perspectives as they can have an active function in wound healing, such as faster healing minimizing scar formation and prepared wound bed for subsequent grafting. However, cell-based therapies encounter some limitations due to regulatory hurdles, as they are considered as "Advanced Therapy Medicinal Products," which imposes the same industry-destined good manufacturing practices as for pharmaceutical products and biological drug development. Future Directions: Further improvements in clinical outcome can be expected principally with the use of cell-based therapies; however, hospital exemptions are necessary to assure accessibility to the patient and safety without hindering advances in therapies.

Keywords: biological bandages; first cover; skin graft; temporary substitute.

© Philippe Abdel-Sayed, et al. 2019; Published by Mary Ann Liebert, Inc.

Figures

Philippe Abdel-Sayed, PhD

Lee Ann Applegate, PhD

Figure 1.

Upper panel: Schematic illustration of split-thickness skin autografting and cell-based autografting; lower panel: Fabrication process of CEA and CDEA. CDEA, cultured dermal–epidermal autograft; CEA, cultured epithelial autografting. Color images are available online.

Figure 2.

Skin substitutes classified into permanent and temporary substitutes. For both categories, products have evolved from conventional therapies to bioengineered products combining various cells and biomaterials as strategies to improve wound healing. Color images are available online.

Figure 3.

Use of biological bandages as cover for skin donor sites. (A) Back of pediatric patient with a deep burn at the right flank; (B) skin graft taken with dermatome on healthy sites of the back; (C) application of the biological bandages on the donor sites of the back; (D) re-epithelization of the skin donor sites after application of the biological bandages. Color images are available online.

Figure 4.

Timeline of evolution of the first covers used at CHUV burn unit and the implementation of cell therapies. Color images are available online.

Figure 5.

Photographs of a burn patient treated in a first time with E-Z Derm® as first cover (left panel), and with biological bandages (right panel). Biological bandages are applied the same day after E-Z Derm removal and debridement; they demonstrate superior outcomes in comparison with porcine substitute, as shown by the lack of necrotic tissue, the absence of the staples and ease of handling. Color images are available online.

Figure 6.

(A) Steady increase over time of production and use of biological bandages at the burn units of the Lausanne University Hospital, while number of patients admitted to the burn center has remained constant. We can see that this increase of use of biological bandages is mainly due to the introduction of this therapy as first cover for the adult patients. (B) Increase of the mean number of bandages used per patient, with a constant TBSA over time, which is relevant to the fact that this therapy has been more used in clinical routine and not because of higher burn surface. TBSA, total body surface area.