Bilirubin as an inhibitor of cartilage metabolism: Effect on avian chondrocyte proliferation in cell culture

Abstract

Elevated levels of bilirubin and other tetrapyrroles are common to a number of chronic hematologic and liver diseases that can result in growth failure. This report establishes a cellular model system for the study of these endogenous growth inhibitors. Primary chondrocyte cultures were prepared from embryonic chick cartilage; cells were incubated (0.3 X 10(5) cells per plate) in tissue culture medium containing 10% fetal bovine serum (FBS) with or without added bilirubin, 0.01-0.10 mM. Bilirubin caused profound, dose-dependent inhibition of chondrocyte proliferation: after 7 days, control incubations contained 11.45 +/- 2.0 X 10(5) cells per plate versus 4.92 +/- 0.55 X 10(5) cells per plate for wells with added 0.01 mM bilirubin and 1.76 +/- 0.30 X 10(5) for cultures with added 0.05 mM bilirubin. In chondrocytes cultured for 3 days, the addition of 0.05 mM bilirubin was associated with inhibition of [3H]thymidine incorporation into DNA (47 +/- 5% of control), [3H]uridine incorporation into RNA (11 +/- 0.05% of control), and [14C]leucine incorporation into proteins (16 +/- 1% of control). The inhibition of chondrocyte proliferation induced by a range of bilirubin concentrations (0.01-0.10 mM) was in no way attenuated by the addition of physiologic concentrations of albumin (4 g/dl). After 3 days in media containing bilirubin or heme (at equimolar concentrations), chondrocytes were subsequently incubated in FBS alone for an additional 3 days; only partial reversal of the bilirubin (or heme)-induced inhibition was then observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of bilirubin and sera from jaundiced patients on osteoblasts: Contribution to the development of osteoporosis in liver diseases

“…Thus, as observed by Janes et al, the presence of sera with a high concentration of bilirubin resulted in decreased cell viability 5. Moreover, depression of proliferation of other cells of calcifying tissues by bilirubin has also been reported 21. The current study, however, adds new information, because reduced osteoblast viability was observed with sera samples from jaundiced patients, particularly in the experiments performed with the highest bilirubin concentration in culture media (66 μM).…”

Bile acids and bilirubin effects on osteoblastic gene profile. Implications in the pathogenesis of osteoporosis in liver diseases

“…observed that plasma with high concentrations of bilirubin resulted in decreased human osteoblast-like cells proliferation [19]. Similarly, bilirubin induced a marked dose-dependent inhibition of avian chondrocytes proliferation [20].…”

Bile acids and bilirubin effects on osteoblastic gene profile. Implications in the pathogenesis of osteoporosis in liver diseases

“…observed that plasma with high concentrations of bilirubin resulted in decreased human osteoblast-like cells proliferation [19]. Similarly, bilirubin induced a marked dose-dependent inhibition of avian chondrocytes proliferation [20]. Previous studies from our group have shown a decrease of human osteoblastic cells viability and differentiation when bilirubin and sera from jaundiced patients was added to the culture media [7].…”