Characterization of MSC cultures derived from IDUA KO mice. When cultured in differentiation-inducing media, the MSCs readily differentiated into adipocytes (A-II) or osteoblasts (A-IV), as determined via staining with Oil Red O and Alizarin Red, respectively. Control cultures stained with the same reagents (Oil Red O or Alizarin Red in A-I and A-III, respectively) demonstrate the adherent, fibroblastoid morphology that characterizes the MSC cultures. The original magnification is 100×. As determined via immunophenotyping, the MSC cultures were negative for CD11b and CD45 and positive for CD29 and CD44. The MSCs and control cells are shown in grey and white, respectively (B).