The Current Challenges on Spray-based Cell Delivery to the Skin Wounds.

Cell delivery via spray instruments is a promising and effective method in tissue engineering and regenerative medicine. It is used for treating different acute and chronic wounds, including burns with different etiologies, chronic diabetic or venous wounds, post-cancer surgery, and hypopigmentation disorders. Cell spray can decrease the needed donor site area compared to conventional autologous skin-grafting. Keratinocytes, fibroblasts, melanocytes, and mesenchymal stem cells (MSCs) are promising cell sources for cell spray procedures. Different spray instruments are designed and utilized in order to deliver the cells to the intended skin area. In an efficient spray instrument, cell viability and wound coverage are two determining parameters influenced by various physical and biological factors such as air pressure, spraying distance, viscosity of suspension, stiffness of the wound surface, and velocity of impact. Besides, in order to improve cell delivery by spray instruments, some matrices and growth factors can be added to cell suspensions. This review focuses on the different types of cells and spray instruments used in cell delivery procedures. It also discusses physical and biological parameters associated with cell viability and wound coverage in spray instruments. Moreover, the recent advances in co-delivery of cells with biological glues and growth factors, as well as clinical translation of cell spraying have been reviewed.