Hepatocyte-conditioned medium sustains endothelial differentiation of human hematopoietic-endothelial progenitors.
Liver neo-angiogenesis plays a fundamental role in physiological and pathological processes such as regeneration, cirrhosis, autoimmune hepatitis, and alcoholic liver disease. How liver parenchymal cells influence angiogenesis is largely unknown. We studied the influence of soluble factors released by hepatocytes on hematopoietic and endothelial cell differentiation. Human CD34+ cells cultured for several weeks in a hepatocyte-conditioned medium gradually decrease the expression of CD34 and CD133 markers (i.e. after 4 weeks from 85% and 69%, respectively, to 6% and 3%, respectively), whereas expression of CD144 and CD14 cell markers increased (from 2% and 8%, respectively, to 54% and 55%, respectively). The cells' capacity to form hematopoietic colonies in methylcellulose declined with time, whereas they acquired endothelial morphology, expressed endothelial markers, and incorporated into newly forming vascular structures both in vitro and in vivo. Cultured single CD34+ cells formed colonies expressing both hematopoietic (CD45+) and endothelial (CD144+) markers, suggesting they constitute a bona fide hemangioblast population.


CONCLUSIONS
This system allowed subsequent stages of differentiation of hematopoietic cells to endothelial cells to be defined, underlining the strict interrelationship between endothelial and hematopoietic cells in a hepatocyte environment.
Bordoni
Veronica
V
National Institute for Infectious Diseases L. Spallanzani, IRCCS, Rome, Italy.
Alonzi
Tonino
T
Zanetta
Lucia
L
Khouri
Daniele
D
Conti
Annarita
A
Corazzari
Marco
M
Bertolini
Francesco
F
Antoniotti
Pierluigi
P
Pisani
Giuseppe
G
Tognoli
Francesca
F
Dejana
Elisabetta
E
Tripodi
Marco
M
D015703:Antigens, CD / Q000032:analysis; D018952:Antigens, CD34 / Q000032:analysis; D015820:Cadherins / Q000032:analysis; D002454:Cell Differentiation / Q000502:physiology*; D049109:Cell Proliferation; D002478:Cells, Cultured; D017077:Culture Media, Conditioned / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000166:cytology*; D005434:Flow Cytometry; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D022781:Hepatocytes / Q000502:physiology*; D006801:Humans; D017493:Leukocyte Common Antigens / Q000032:analysis; D000099152:Cadherin 5
D015703:Antigens, CD; D018952:Antigens, CD34; D015820:Cadherins; D017077:Culture Media, Conditioned; D017493:Leukocyte Common Antigens; D000099152:Cadherin 5; C516769:PTPRC protein, human