Studies onin vitro evaluation for the biocompatibility of various biomaterials: Inhibitory activity of various kinds of polymer microspheres on metabolic cooperation

Abstract

Gap junctional intercellular communication is a function that plays an important role in maintaining cell and tissue homeostasis and in regulating cell growth, development, and differentiation. Change in this function when contacting fibroblasts with various polymer microspheres was estimated using the metabolic cooperation assay system. When the cells were in contact with the microspheres after their adhesion onto a substrate, the function did not alter. However, when they were in contact with precoated microspheres on test dishes, the function was inhibited as the quantity of microspheres increased. Moreover, the inhibition level increased as the diameters of polyethylene and polystyrene microspheres decreased. However, no inhibition was observed if precoated microspheres were composed from poly(L-lactic acid). These findings suggest that the size and the material of microspheres, and how cells recognize the microspheres, are factors affecting cell function of gap junctional intercellular communication. Therefore, estimating this function may provide valuable information about the biocompatibility of many kinds of materials even in the form of particles.

Biocompatibility of Various Kinds of Polymer Microspheres Estimated from Their Effect on Gap Junctional Intercellular Communication of Fibroblasts

“…4 is consistent with our previous study. 18) However, the expression status of connexin 43 in the cells contacted with PS microspheres for 1 day was almost similar in all cases, inconsistent with their inhibitory activities on the GJIC function. In addition, a change in the phosphorylated status of the connexin was hardly indicated after 3-day incubation with PS microspheres.…”

“…In our previous study, the inhibitory activity of added PLLA microspheres could not be detected by metabolic cooperation (MC) assay system. 18) Moreover, the inhibitory activity of microspheres could not be found out when the microspheres were added after cell attachment on test dishes by the MC assay system. However, the inhibitory activity was detected using the FRAP analysis in this study.…”

“…[15][16][17][18] GJIC is a function that plays an important role in maintaining cell and tissue homeostasis by exchanging low molecular weight molecules, that results in regulating cell growth, development and differ- * Corresponding author: E-mail: nakaoka@nihs.go.jp entiation of cells. 19,20) Therefore, it is reasonable that disruption of this function is the cause of many kinds of diseases.…”

“…18) Briefly, polymer microspheres were sterilized by dispersing in 70% ethanol solution, followed by centrifugation in sterile condition to remove ethanol. The microspheres were dispersed in sterile methanol or test medium at specified concentration.…”

“…19,20) Therefore, it is reasonable that disruption of this function is the cause of many kinds of diseases. In the previous report, 18) we have estimated an inhibitory activity of polymer microspheres, which were used as model wear debris from biomedical polymer in vivo, on the GJIC using a metabolic cooperation assay system that is a method for estimating the GJIC function of Chinese hamster-derived fibroblasts. We concluded that estimating the inhibitory activity of the microspheres on the GJIC might be useful for considering their side effects in body.…”