[Osteogenesis of human vascular endothelial cells in culture].
BACKGROUND
Mesenchymal stem cells have the potential to differentiate into several types of cells including osteoblasts. These stem cells have cell surface markers found on cells of endothelial and subendothelial origin of the umbilical cord vein. Taking this into consideration we have postulated that human umbilical vein endothelial cells (HUVEC) could present osteogenic differentiation as well. Gene activation that could drive osteogenic differentiation is regulated by exogenous and endogenous factors.


OBJECTIVE
The induction osteogenesis in HUVEC.


METHODS
We used: a) an osteogenic medium containing 0.1 microM dexamethasone, 10 microM beta-glycerophosphate, 50 microM L-ascorbic-acid 2-phosphate, 20% MCGS serum; and b) a treatment with DNA demethylating agents hydralazine and 5'-aza-2'-deoxycytidine (0.39-200 microM). Phenotypic characteristics of HUVEC were their spindle and stellate shapes with fine homogenous cytoplasm, typically associated with fibroblast-like cells.


RESULTS
The control cells (without osteogenic treatment) exhibited little extracellular matrix, whereas the osteogenically treated cells appeared shortened and flattened, and they were surrounded by extracellular matrix that subsequently became mineralized in vitro. After 28 days in culture, morphologic and histochemical studies confirmed that osteogenic medium had a strong stimulatory effect on the alkaline phosphatase activity of endothelial cells, a very early marker of cell differentiation into the osteogenic lineage. Hydralazine and 5'-aza-2'-deoxycytidine, two drugs utilized in chromatin remodeling leading to gene re-expression of inactivated DNA hypermethylated islands, did not favor osteoblast differentiation.


CONCLUSIONS
Our study shows that HUVEC can differentiate along an osteogenic lineage and thus provide an alternative source for cell-based therapies and tissue engineering strategies.
Aguilar-Vázquez
Raúl
R
Laboratorio de Immunología, Unidad de Morfofisiología, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Tlanepantla, México.
Carballo-Molina
Oscar Alejandro
OA
Collazo-Navarrete
Omar
O
Guerrero-Rangel
Maribel
M
Saucedo-Campos
Alberto Daniel
AD
Barrera-Lechuga
Paulina
P
López-Marure
Rebeca
R
Cáceres-Cortés
Julio Roberto
JR
D000469:Alkaline Phosphatase / Q000378:metabolism; D001205:Ascorbic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D001374:Azacitidine / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D048430:Cell Shape / Q000187:drug effects; D002478:Cells, Cultured / Q000187:drug effects; D003470:Culture Media / Q000494:pharmacology; D019175:DNA Methylation / Q000187:drug effects; D003907:Dexamethasone / Q000494:pharmacology; D042783:Endothelial Cells / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology*; D005994:Glycerophosphates / Q000494:pharmacology; D006801:Humans; D006830:Hydralazine / Q000494:pharmacology; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D010012:Osteogenesis / Q000187:drug effects / Q000502:physiology*; D014471:Umbilical Veins / Q000166:cytology
D003470:Culture Media; D005994:Glycerophosphates; C011669:ascorbate-2-phosphate; D006830:Hydralazine; D003907:Dexamethasone; D000469:Alkaline Phosphatase; D001374:Azacitidine; D001205:Ascorbic Acid; C031463:beta-glycerophosphoric acid