Adhesion strength of individual human bone marrow cells to fibronectin. Integrin beta(1)-mediated adhesion

The purpose of this work was to study the adhesion strength of individual b one marrow cells, using a micropipette aspiration technique. The adhesion s trength of the primary human bone marrow cells to fibronectin-coated substr ate, by blocking the beta (1) integrin with and without antibodies, was als o determined. Human bone marrow stromal cells of the second passage were se eded at a density of 500cells/cm(2) on two different substrates: plastic cu lture dish (PCD) and PCD coated with fibronectin. In short adhesion times ( 15-180 min) the cells attached without spreading and remained almost spheri cal. A negative pressure of about 3500 Pa was applied, through the micropip ette, on individual bone marrow cells and the detach process was recorded. The tip of the micropipette was bent at an 130 degrees angle to the corpus of the pipette and it was manipulated to be on the upper side of the cell a nd vertically to the bottom of the plate. It was observed from the experime nts that the cells exhibited smaller adhesion strength at early adhesion ti mes (30-85 min). After 85 min the adhesion strength increased abruptly and remained relatively constant for the adhesion period from 85 to 180 min for all substrates. Monoclonal antibodies against integrin subunit beta (1) we re used for integrin blocking experiments. The data suggested that the atta chment of osteoblasts to a plastic culture dish without fibronectin coating occurred earlier than to the one coated with fibronectin PCD. In longer ad hesion time the coating with fibronectin increased the adhesion strength at 107%. Blocking of integrin beta (1) with monoclonal antibody resulted in d ecrease of the adhesion strength at 49%. (C) 2001 Kluwer Academic Publisher s.