Figure 3.

The MLD brain promotes migration of OLPs and absence of ARSA is not a limiting factor for their migration. OLPs were plated on agarose drops and incubated in the presence of brain slices prepared from MLD or wild-type pups for 24 h before X-gal staining. A, The number of cells per area surrounding the agarose drop was counted. MLD tissue promoted a migration of wild-type or MLD OLPs out of the agarose drop, similar to the OLP migration seen in B104 conditioned medium. In contrast, healthy tissue promoted migration much less efficiently. B, C, Examples of β-gal-stained wild-type OLPs that migrated out the agarose drop after 24 h of culture with MLD (B) and wild-type (C) brain slices. The arrows demarcate the limit of the agarose drop. D–H, Transplanted MLD and wild-type mice were grafted with ARSA^−/− OLPs and killed at 7 and 15 d after transplantation. Grafted cells migrated extensively to the corpus callosum (cc) and cortex (F) and SVZ (D, E). In contrast, ARSA^−/− OLPs migrated poorly in wild-type brain, even 15 d after transplant (G–H). cp, Caudate–putamen; LV, lateral ventricle; dpi, days postinjection. Results are expressed as mean value ± SEM.