Influence of fibrin matrices and their released factors on epidermal substitute phenotype and engraftment.

Cultured epithelial autografts (CEAs) represent a life-saving surgical technique for full-thickness skin burns covering more than 60% total body surface area. However, CEAs present numerous drawbacks leading to heavy cosmetic and functional sequelae. In our previous study, we showed that human plasma-based fibrin matrices (hPBM) could improve the reparative potential of CEAs. Therefore, in the present work, we sought to investigate the role of hPBM compared with fibrin from purified fibrinogen (FPF) or plastic support on epidermal substitute formation and engraftment. The use of hPBM for epidermal substitute culture improved keratinocyte migration, proliferation, and epidermal substitute organization to a better extent than FPF in vitro. Both fibrin matrices favored greater dermal-epidermal junction protein deposition and prevented their degradation. Keratinocyte differentiation was also decreased using both fibrin matrices. Basement membrane protein deposition was mainly influenced by matrix whereas growth factors released from fibrin especially by hPBM were shown to enhance in vitro keratinocyte migration, proliferation, and epidermal substitute organization. Ultimately, epidermal substitutes grown on hPBM displayed better engraftment rates than those cultured on FPF or on plastic support in a NOD-SCID model of acute wound with the formation of a functional dermal-epidermal junction. Together, these results show the positive impact of fibrin matrices and their released growth factor on epidermal substitute phenotype and grafting efficiency. Fibrin matrices, and especially hPBM, may therefore be of interest to favor the treatment of full-thickness burn patients.

Biotechnological Management of Skin Burn Injuries: Challenges and Perspectives in Wound Healing and Sensory Recovery.

Many wound management protocols have been developed to improve wound healing after burn with the primordial aim to restore the barrier function of the skin and also provide a better esthetic outcome. Autologous skin grafts remain the gold standard in the treatment of skin burn, but this treatment has its limitation especially for patients presenting limited donor sites due to extensive burn areas. Deep burn injuries also alter the integrity of skin-sensitive innervation and have an impact on patient's quality of life by compromising perceptions of touch, temperature, and pain. Thus, patients can suffer from long-term disabilities ranging from cutaneous sensibility loss to chronic pain. The cellular mechanisms involved in skin reinnervation following injury are not elucidated yet. Depending on the depth of the burn, nerve sprouting can occur from the wound bed or the surrounding healthy tissue, but somehow this process fails to provide correct reinnervation of the wound during scarring. In addition, several clinical observations indicate that damage to the peripheral nervous system influences wound healing, resulting in delayed wound healing or chronic wounds, underlining the role of innervation and neuromediators for normal cutaneous tissue repair development. Promising tissue engineering strategies, including the use of biomaterials, skin substitutes, and stem cells, could provide novel alternative treatments in wound healing and help in improving patient's sensory recovery.

Bioengineering a human plasma-based epidermal substitute with efficient grafting capacity and high content in clonogenic cells.

UNLABELLED: Cultured epithelial autografts (CEAs) produced from a small, healthy skin biopsy represent a lifesaving surgical technique in cases of full-thickness skin burn covering >50% of total body surface area. CEAs also present numerous drawbacks, among them the use of animal proteins and cells, the high fragility of keratinocyte sheets, and the immaturity of the dermal-epidermal junction, leading to heavy cosmetic and functional sequelae. To overcome these weaknesses, we developed a human plasma-based epidermal substitute (hPBES) for epidermal coverage in cases of massive burn, as an alternative to traditional CEA, and set up critical quality controls for preclinical and clinical studies. In this study, phenotypical analyses in conjunction with functional assays (clonal analysis, long-term culture, or in vivo graft) showed that our new substitute fulfills the biological requirements for epidermal regeneration. hPBES keratinocytes showed high potential for cell proliferation and subsequent differentiation similar to healthy skin compared with a well-known reference material, as ascertained by a combination of quality controls. This work highlights the importance of integrating relevant multiparameter quality controls into the bioengineering of new skin substitutes before they reach clinical development. SIGNIFICANCE: This work involves the development of a new bioengineered epidermal substitute with pertinent functional quality controls. The novelty of this work is based on this quality approach.

Integration of scaffolds into full-thickness skin wounds: the connexin response.

Scaffolds have been reported to promote healing of hard-to-heal wounds such as burns and chronic ulcers. However, there has been little investigation into the cell biology of wound edge tissues in response to the scaffolds. Here, we assess the impact of collagen scaffolds on mouse full-thickness wound re-epithelialisation during the first 5 days of healing. We find that scaffolds impede wound re-epithelialisation, inducing a bulbous thickening of the wound edge epidermis as opposed to the thin tongue of migratory keratinocytes seen in normal wound healing. Scaffolds also increase the inflammatory response and the numbers of neutrophils in and around the wound. These effects were also produced by scaffolds made of alginate in the form of fibers and microspheres, but not as an alginate hydrogel. In addition, we find the gap junction protein connexin 43, which normally down-regulates at the wound edge during re-epithelialisation, to be up-regulated in the bulbous epidermal wound edge. Incorporation of connexin 43 antisense oligodeoxynucleotides into the scaffold can be performed to reduce inflammation whilst promoting scaffold biocompatibility.