(188by) Microparticles for Skin Wound Healing

Endothelial cells line blood vessel walls and provide an intricate super highway for nutrient
and gas delivery throughout the body. Thus, endothelial cells are in most tissues of the body including organs, muscles, and bones. Curiously, in skin only the dermis is vascularized, whereas the epidermis receives nutrients through diffusion from the dermis and from the environment. Endothelial cells are crucial for maintaining this homeostasis as skin relies on dense vascular networks to deliver excesses of nutrients such that the epidermis is properly maintained. However, in severe burns, abrasions, or ulcers, the skin loses its ability to completely regenerate leaving the formation of a scar. The scar tissue formed consists of extracellular matrix proteins aggregated to seal the wound site. However, the use of biomaterials as vehicles for cellular delivery to augment tissue repair response has the potential to prevent malignant bodily responses. Delivery of endothelial cells to the wound site would increase vascularization marking an improvement in vital nutrient delivery. Herein is described a simple but effective method for endothelial cell attachment. Poly-l-lytic glycolic acid (PLGA) microparticles were fabricated using a modified version of the single emulsion solvent-evaporation method utilizing a proprietary flow-focusing device. Additionally, particles were surface functionalized for cellular attachment by physical adsorption of poly-l-lysine (PLL), gelatin, or a combination of both. Finally, particles were assessed for cell attachment and proliferation. PLGA microparticles functionalized with PLL and gelatin
successfully attached HUVEC cells, maintained cell viability, and enabled proliferation. This
proves that a simple fabrication method of microparticles coupled with facile physical adsorption is capable of effectively binding cells for therapeutic use as well as manufacturing large particles with sizable control.