Multilayer microcapsule of hyaluronic acid derivative containing gelatinmicroparticle with enclosed cells

IntroductionEnclosing cells in hydrogel microcapsules has been studied intensively in tissue engineering. Among hydrogel substrates, gelatin is obtained by partial hydrolysis of collagen, the most abundant protein in animal tissues. Due to the presence of lysine, arginine and connecting peptides such as arginine-glycine-aspartic acid (RGD) groups, gelatin promotes cell attachment and growth. On the other hand, hyaluronic acid (HA) is a non-adhesive and hydrophilic polymer. HA is well recognized as a major constituent of tissue.ObjectivesThis study aimed at the microencapsulation of cells in liquefied gelatin microparticles covered with HA derivative in two sequential processes. The spherical hydrogel vehicles are produced through coaxial double-orifice microfluidic system.MethodsThe encapsulation of HepG2 cells was carried out in gelatin microparticles. And then gelatin microparticles were coated by the HA-Ph under a mild condition of enzymatic reaction. For this method, gelatin was dissolved at 7.5% (w/v) in PBS and extruded from a coaxial microfluidic device. Gelatin solution (37oC) containing HepG2 cells at 1×107 cells mL-1 was made to flow from an inner tube at 0.075 mL min-1. Paraffin containing lecithin was extruded through an outer tube at 2.9 mL min-1. Finally, the obtained spheroid tissue was wrapped with10T1/2 cells attaching on the HA-Ph layer.ResultsThe viability of cells harvested from the HA-Ph microcapsules was 91.6±2.0%. HA-Ph encapsulation process imposed a negligible effect on the percentage of viable cells. It was also confirmed that H2O2 did not have a harmful effect on the growth of harvested cells. The cells in the HA-Ph microcapsules attached and elongated on inner surfaces of the microcapsules and grew to fulfill the core cavities of microcapsules at day 10. Moreover, with respect to wrapping tissues, the cells could attach on the outer surfaces of microcapsules after 4 h. The outer surfaces of microcapsules were fully covered with actively grown cells.ConclusionThe cell growth on the outer surface of HA-Ph microcapsule would be the unexpected behavior of cells because HA is poor in cell- adhesive ability. One possibility is that liquefied gelatin in the core cavities diffuses into the outer HA-Ph layers and affects the composition of the HA-Ph layers

کلیدواژه ها:

Microcaspule ، Hyaluronic acid ، Gelatin ، Microfluidic system ، Spherical tissue