Mitogenic activity of different laminin isoforms.

Freshly isolated human bone marrow mononuclear cells (A) and a CD34⁺ cell population highly enriched by MiniMACS separation (B) were incubated with different laminin isoforms and analyzed in a nonradioactive proliferation assay. No significant proliferation-inducing effect could be observed with LN-1 and LN-2/4 (A). However, LN-10/11 and a laminin preparation isolated from human LTMCs had a strong mitogenic effect on the heterogeneous mononuclear cell population (A) but also on the purified CD34⁺progenitor cells (B). The mitogenic effect of these 2 laminin preparations was dose-dependent. A more than 6-fold increase in mononuclear cell numbers could be detected at 1.0 μg/mL, which was further enhanced at 10 μg/mL (A).