Wyj. Kao et al., THEORETICAL-ANALYSIS OF IN-VIVO MACROPHAGE ADHESION AND FOREIGN-BODY GIANT-CELL FORMATION ON STRAINED POLY(ETHERURETHANE UREA) ELASTOMERS, Journal of biomedical materials research, 28(7), 1994, pp. 819-829
Quantitative description of foreign body giant cell (FBGC) formation o
n poly(etherurethane urea) (PEUU) surfaces as a function of time can c
onceivably predict the effects of polymer characteristics on cellular
responses in vivo. In the present study, the formation of FBGCs on str
ained and unstrained PEUUs was quantified with two parameters: the den
sity of adherent macrophages present initially that participate in FBG
C formation (d(o)) and the rate constant for cell fusion (k); both kin
etic parameters were used to calculate the time-dependent F;BGC densit
y (d(fc)). Relationships were sought between results of the cellular a
nalysis and the extent of environmental stress cracking (ESC), as char
acterized by scanning electron microscopy. Surface degradation was sem
iquantified with percent light transmittance. The materials used were:
base PEUU, base PEUU with 1% Santowhite(R) antioxidant powder, base P
EUU with 5% Methacrol 2138F(R) antifume agent, and base PEUU with both
1% Santowhite(R) and 5% Methacrol 2138F(R). A comparison of unstraine
d base PEUU with base PEUU strained to 400% elongation indicated that
the rate of cell fusion, but not d(o) and d(fc), increased in the pres
ence of strain. In all strained samples, additives that strongly affec
ted the ESC also influenced FBGC kinetic parameters. Strained PEUU con
taining Santowhite(R) had the lowest d(o), the slowest rate of cell fu
sion, and lowest d(fc), and the least incidence of ESC. The results su
ggest that the incidence of ESC in PEUU was decreased in the presence
of Santowhite(R), which also lowered the number of adherent macrophage
s participating in FBGC formation, the rate of FBGC formation and the
subsequent FBGC density. These studies also indicate that strain in PE
UUs does not directly modulate the adherent macrophage and FBGC densit
y. Further studies are necessary to delineate the relationship between
PEUU strain and adherent macrophage and FBGC activation, which leads
to the exocytosis of degrading agents and the observed incidence of bi
odegradation. (C) 1994 John Wiley and Sons, Inc.