Isolation from fetal bovine serum of a fragment b of complement factor B-like protein improving a long-term survival of human endothelial cells

Beta-2-glycoprotein I is growth regulated and plays a role as survival factor for hepatocytes

Beta-2-glycoprotein I (beta(2)GPI) is mainly produced by the liver and is found in plasma partially associated to lipoproteins. Although various properties have been attributed to this protein, its physiological role remains still unclear. We investigated its expression in cultured liver cells and in regenerating liver. Expression studies in HepG2 cells demonstrate that beta(2)GPI mRNA is regulated in a cell cycle-dependent manner, with very low expression in low cycling conditions and increasing levels in proliferating cells. p21 WAF-dependent growth arrest, induced by butyrate treatment, down-regulate beta(2)GPI mRNA levels. Immunolocalization in normal rat liver shows a non-homogeneous pattern, being mainly present in the centrolobular area; post-hepatectomy regenerating rat liver is uniformly immunostained and mitotic elements show the highest protein expression. Albumin gene expression, studies as control liver specific product, was not affected by sodium butyrate induced growth arrest. As previously reported for endothelial cells, beta(2)GPI behaves as survival factor for HepG2 cells: when increasing amounts of the protein (10-50 microg) have been added to serum deficient cultured liver cells a progressive reduced cell loss was observed. In conclusion, the present data demonstrate that beta(2)GPI gene expression is strictly related to the proliferative status of hepatic cells and that this protein could play a role in maintaining liver cells vitality when exposed to different stress factors such as regeneration after partial hepatectomy or growth factors depletion.

Action of dipyridamole and warfarin on growth of human endothelial cells cultured in serum-free media

OBJECTIVE

To study the anti-proliferative effect of Dipyridamole (anti-platelet), Dipyridamole with Warfarin, and Warfarin (anticoagulant) alone, in human endothelial cells in vitro.

DESIGN AND METHODS

Human endothelial cells were harvested from umbilical cords. Primary cultures were usually successful. However, subculture yields were usually contaminated with smooth muscle cells. We have developed an improved method for the isolation of endothelial cells by using Collagenase II, coating the culture flask with fibronectin and using serum-free media. The endothelial cells were characterised by anti-PECAM-1/PE (CD31) using Flow Cytometry with viability of 95% after trypsinization with 0.05% Trypsin and 1 mM EDTA. Growth and proliferation studies were performed in vitro in the presence of 5 microM Dipyridamole, 5 microM Dipyridamole with 5 microM Warfarin, 5 microM Warfarin alone by cell counts, (3)H-thymidine and (3)H-leucine incorporation.

RESULTS

The incorporation of (3)H-Leucine at day 6 in each test condition revealed no significant change. Control 12678 +/- 2968 CPM, Dipyridamole 8698 +/- 189 CPM, Dipyridamole and Warfarin 7541 +/- 413 CPM, and Warfarin alone 10711 +/- 732 CPM. With the incorporation of (3)H-Thymidine, Dipyridamole alone as well as Dipyridamole with Warfarin reduced the basal proliferation rates significantly when compared to controls. Control 14355 +/- 4441 CPM, Dipyridamole 1100 +/- 152 CPM (p<0.05), Dipyridamole with Warfarin 1092 +/- 272 CPM (p<0.05). Warfarin alone did not reduce proliferation significantly 12870 +/- 2677 CPM (NS).

CONCLUSIONS

We have developed a method to isolate pure endothelial cells from human umbilical cords using Serum-Free Media (SFM). EC with high purity was characterised by anti-PECAM-1/PE (CD31) using Flow Cytometry. Dipyridamole at a concentration of 5 microM inhibited the proliferation of endothelial cells at day 6 by 93%. These techniques can be used for routine analysis and proliferation studies.