Exogenous HA increased contractility in serum-starved human PDL cells. Representative fluorescent images and traction forces of a fixed and stained (a) human PDL cell, (b) PDL cell treated with hyaluronan (HA), and (c) and PDL cell treated with hyaluronidase (HYAL) and HA, (red: microposts; green: actin; blue: nucleus). Traction forces were measured by analyzing the deflections of the microposts and reported as force vectors (arrows). (d) Traction forces of human PDL cells exposed to exogenous HA (population size of experimental repetition: n1 = 11, n2 = 18, n3 = 20; P = 0.011) or HYAL+HA (n1 = 10, n2 = 13, n3 = 13; P = 5.58e-4) indicate that both treatments induced significant cell contractility compared to the controls (n1 = 10, n2 = 17, n3 = 16). (E) Cell spread area remained comparable to controls (n1 = 10, n2 = 17, n3 = 16), such that it was unaffected by HA (n1 = 11, n2 = 18, n3 = 20) or the combination of HYAL+HA (n1 = 10, n2 = 13, n3 = 13) in human PDL cells. Data shown as average ± SEM from three experimental replicates. Asterisk indicates P < 0.05 (Student t-test).