Euglena gracilis–Derived Extracellular Vesicles as Skin-Regenerative Wound Healing Agents

Extracellular vesicles are known as an important mediator for signaling in cell-cell communication and cellular processes including immune response and antigen presentation. Since extracellular vesicles contain therapeutic proteins, a variety of cell therapeutic strategies are developing while avoiding side effects such as low survival rate and immune rejection response associated with direct use of cells as a therapeutic agent. Most of the exosome studies conducted so far are based on animal-originated cells. Recently, there are challenging attempts to extract extracellular vesicles from other types of raw materials such as plant cells and microalgae. The approach to obtain extracellular vesicles from microalgae is of special interest because they have abundant biomolecules such as proteins, vitamins, minerals, and amino acids. This study proposes using microalgae containing carbohydrate bioactives, an Euglena gracilis–derived extracellular microvesicle (EMV_EG) system, for enhanced skin regeneration. The critical deformation ratio, 1.67, during cell extrusion enables us to tune the particle size of the EMV_EG at approximately 1 μm, thus satisfying the encapsulation yield of b-1,3-glucan and the cellular delivery performance. In vitro 5-bromo-2’-deoxyuridine and cell scratch assays revealed that the EMV_EG promoted the proliferation and migration of skin cells, thereby increasing both collagen synthesis and the expressions of proliferation-associated proteins. An ex vivo wound healing test using both artificial and porcine skin revealed that similar to that seen using b-1,3-glucan, the EMV_EG could substantially increase the cell population, expressing the proliferation-related protein, termed proliferating cell nuclear antigen. These results demonstrate that our EMV_EG system shows considerable potential in the field of skin regeneration. This technique is expected to design new types of extracellular vesicles that are applicable for skin regeneration in the pharmaceutical and cosmetic industries.