This review gives an updated overview on keratinocyte transplantation in burn wounds concentrating on application methods and future therapeutic cell delivery options with a special interest in hydrogels and spray devices for cell delivery.To achieve faster re-epithelialisation of burn wounds, the original autologous keratinocyte culture and transplantation technique was introduced over 3 decades ago. Application types of keratinocytes transplantation have improved from cell sheets to single-cell solutions delivered with a spray system. However, further enhancement of cell culture, cell viability and function in vivo, cell carrier and cell delivery systems remain themes of interest.Hydrogels such as chitosan, alginate, fibrin and collagen are frequently used in burn wound care and have advantageous characteristics as cell carriers.Future approaches of keratinocyte transplantation involve spray devices, but optimisation of application technique and carrier type is necessary.

The development of new materials for clinical use is limited by an onerous regulatory framework, which means that taking a completely new material into the clinic can make translation economically unfeasible. One way to get around this issue is to structure materials that are already approved by the regulator, such that they exhibit very distinct physical properties and can be used in a broader range of clinical applications. Here, the focus is on the structuring of soft materials at multiple length scales by modifying processing conditions. By applying shear to newly forming materials, it is possible to trigger molecular reorganization of polymer chains, such that they aggregate to form particles and ribbon-like structures. These structures then weakly interact at zero shear forming a solid-like material. The resulting self-healing network is of particular use for a range of different biomedical applications. How these materials are used to allow the delivery of therapeutic entities (cells and proteins) and as a support for additive layer manufacturing of larger-scale tissue constructs is discussed. This technology enables the development of a range of novel materials and structures for tissue augmentation and regeneration.

Disorganization of the transparent collagenous matrix in the cornea, as a consequence of a variety of infections and inflammatory conditions, leads to corneal opacity and sight-loss. Such corneal opacities are a leading cause of blindness, according to the WHO. Public health programs target prevention of corneal scarring, but the only curative treatment of established scarring is through transplantation. Although attempts to minimize corneal scarring through aggressive control of infection and inflammation are made, there has been little progress in the development of anti-scarring therapies. This is owing to eye drop formulations using low viscosity or weak gelling materials having short retention times on the ocular surface. In this study, we report an innovative eye drop formulation that has the ability to provide sustained delivery of decorin, an anti-scarring agent. The novelty of this eye drop lies in the method of structuring during manufacture, which creates a material that can transition between solid and liquid states, allowing retention in a dynamic environment being slowly removed through blinking. In a murine model of Pseudomonas keratitis, applying the eye drop resulted in reductions of corneal opacity within 16 days. More remarkably, the addition of hrDecorin resulted in restoration of corneal epithelial integrity with minimal stromal opacity endorsed by reduced α-smooth muscle actin (αSMA), fibronectin, and laminin levels. We believe that this drug delivery system is an ideal non-invasive anti-fibrotic treatment for patients with microbial keratitis, potentially without recourse to surgery, saving the sight of many in the developing world, where corneal transplantation may not be available.

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