Biological evaluation of micro-patterned hyaluronic acid hydrogel for bone tissue engineering

Design of micro-patterning of hydrogel is of critical importance in both understanding cellular behaviors and mimicking controlled microenvironments and architectures of diverse well-organized tissues. After micro-patterning of hyaluronic acid (HA) hydrogel on a poly(dimethyl siloxane) substrate, its physical and biological properties have been compared with those of a non-patterned hydrogel for its possible applications in bone tissue engineering. The micro-patterned morphologies of HA hydrogel in both swollen and dehydrated forms have been observed with light microscope and scanning electron microscope, respectively, before and after in vitro cell culture. When MC3T3 bone cells were in vitro cultured on both HA hydrogels, the micro-patterned one shows excellence in cell proliferation and lining for 7 days along the micro-pattern paths over those of the non-patterned one, which have shown less cell-dhesiveness. The cytotoxicity of the micropatterned HA hydrogels was in vitro evaluated by the assays of MTT, BrdU and Neutral red. The viability and morphology of MC3T3 cells on both HA hydrogels were observed with a fluorescence microscope by the live & dead assay, where their viability was confirmed by staining of F-actin development. The results of their H&E staining showed that both micro-patterned and non-patterned hydrogels induced development of tissue regeneration as observed by cell attachment, proliferation, and survivability, but the micro-patterned one induced distinctive patterning of both better initial cells adhesion on the micro-patterns and subsequently development of their proliferation and extracellular matrix, which were considered as important characteristics in their applications to tissue engineering.