In vitro Study of Flavonoids, Fatty Acids, and Steroids on Proliferation of Rat Hepatic Stellate Cells

There is a wealth of evidence that hepatic stellate cells (HSCs) orchestrate most of the important events in liver fibrogenesis. After liver injury, HSCs become activated to a profibrogenic myofibroblastic phenotype and can regulate net deposition of collagens and other matrix proteins in the liver. The proliferation of HSCs is mainly stimulated by the plateletderived growth factor (PDGF). In this study, some compounds from natural resources have been tested for their activity to inhibit PDGF-driven proliferative activity of rat HSCs. Apigenin, quercetin, genistein, daidzin, and biochanin A exhibited > 75% inhibitory activity against HSC-T6. It was found that, γ-linolenic (γ-Ln), eicosapentanoic (EPA) and α- linolenic (α-Ln) acids showed a high inhibitory effect on proliferation of rat HSCs at 50 nmol/l. Cholest-4-ene-3,6-dione and stigmastone-4-en-3,6-dione are the most active steroids with inhibitory activities > 80% and this is most likely due to the presence of the 4-en-3,6-dione moiety in both compounds. These results revealed that the compounds which effectively blocked HSC proliferation may be beneficial in liver fibrosis. Structure-activity relationships (SAR) may provide a basis for rational structure modification.

Effects of EGF, FGF, and PDGF on Canine Chondrocytes in Three-Dimensional Culture

SummaryThree-dimensional (3-D) culture of chondrocytes has been shown to promote cell proliferation, differentiation, and production of matrix while providing for cell morphology and matrix characteristics that resemble normal articular cartilage (1-3). In a recently published study, enhanced glycosaminoglycan (GAG) production was demonstrated in canine chondrocytes in 3-D culture on cancellous bone substrate (3). The effects of growth factors known to be present in cryopreserved bone were suggested to be responsible. Various growth factors including epidermal growth factor (EGF), fibroblast growth factor (FGF), and plateletderived growth factor (PDGF) have been shown to enhance chondrocyte DNA production, mitotic activity, and matrix production (5-10). The objective of the study reported here was to evaluate the effects of one concentration of EGF, FGF, and PDGF on canine chondrocyte proliferation and production of normal matrix constituents in 3-D culture.Canine articular chondrocytes were cultured in three-dimensional medium for 25 days. EGF, FGF, and PDGF were added to the culture medium. Chondrocytes in 3-D culture maintained viability and differentiation. Cell morphology and matrix production resembled that of intact hyaline cartilage. Significant differences with respect to cell counts, glycosaminoglycan concentration, or collagen type II immuno-reactivity as the result of added growth factors were not found.

Adenosine Diphosphate (ADP)-Induced ⍺-Granules Release from Platelets of Native Whole Blood Is Reduced by Ticlopidine but Not by Aspirin or Dipyridamole

SummaryA brief contact between native whole blood and ADP promotes a dose-dependent release of platelet a-granules without a fall in the platelet number. We assessed the “ex vivo” effect of three widely used antiplatelet drugs, aspirin dipyridamole and ticlopidine, on this system. Aspirin (a single 800 mg dose) and dipyridamole (300 mg/die for four days) had no effect, while ticlopidine (500 mg/die for four days) significantly reduced the a-granules release for an ADP stimulation of 0.4 (p <0.02), 1.2 (p <0.01) and 2 pM (p <0.01). No drug, however, completeley inhibits this early stage of platelet activation. The platelet release of α-granules may be related to platelet shape change of the light transmission aggregometer and may be important “in vivo” by enhancing platelet adhesiveness and by liberating the plateletderived growth factor.