Fig. 6.

Both HMW and LMW hyaluronan block OPC maturation in vitro. Hyaluronan (HA) was treated by DNase, RNase, pronase E, or hyaluronidase (Hyal) with β-glucuronidase (β-glu) for 1 h. After enzymatic treatment, samples were boiled for 30 min. OPCs then were treated with the resulting mixtures at a final concentration of 25 μg/mL hyaluronan for 2 d and stained with O1 (green) and olig2 (red). Shown are representative figures of OPCs treated with PBS (A), hyaluronan (B), boiled hyaluronan (C), DNase-treated hyaluronan (D), RNase-treated hyaluronan (E), pronase E treated hyaluronan (F), and hyaluronidase/β-glucuronidase–treated hyaluronan (G). Percent mature oligodendrocytes was measured and compared with control PBS treatment (H). Only treatment with hyaluronidase and β-glucuronidase neutralized the effect of hyaluronan on OPC maturation. OPCs were exposed to 25 μg/mL 870-kDa hyaluronan (HMW hyaluronan), 25 μg/mL 0.8-kDa hyaluronan (LMW hyaluronan), 25 μg/mL hyaluronan disaccharide (diHA), or PBS for 48 h. (I) Representative figures are shown for each treatment and MBP or O1 (green) and olig2 (red) staining. (J) The percent O1^+/olig2⁺ cells (white bars) and MBP⁺/olig2⁺ cells (black bars) was calculated for PBS and hyaluronan exposures. Error bars represent SE. *, P < 0.05 by t test in comparison with control. (Scale bars, 20 μm.)