Liposome-targeted recombinant human acid sphingomyelinase: Production, formulation, and in vitro evaluation

Eur J Pharm Biopharm. 2019 Apr;137:185-195. doi: 10.1016/j.ejpb.2019.02.019. Epub 2019 Feb 25.


Niemann-Pick disease type B is a hereditary rare condition caused by deficiency of the acid sphingomyelinase (ASM) that is needed for lysosomal hydrolysis of sphingomyelin to ceramide and phosphocholine. This deficiency leads to a massive accumulation of sphingomyelin in cells throughout the body, predominantly in the liver, spleen and lungs. Currently, there is no effective treatment available. Olipudase alfa (recombinant human acid sphingomyelinase; rhASM) is an investigational drug that has shown promising results. However, dose-dependent toxicity was observed in mice upon the intravenous administration of rhASM, potentially due to the systemic release of ceramide upon the extracellular degradation of sphingomyelin by rhASM. Using a nanocarrier to deliver the rhASM to cells could improve the therapeutic window by shielding the rhASM to prevent the off-target degradation of sphingomyelin. For this aim, we recombinantly expressed hASM in human cells and loaded it into different liposomal formulations at a drug-to-lipid ratio of 4% (w/w). Among four formulations, the liposomal rhASM formulation with the composition DPPC:DOPS:BMP:CHOL:DiD (59:20:10:10:1 mol%) was selected because of its superiority concerning the encapsulation efficiency of rhASM (21%) and cellular uptake by fibroblasts and macrophages. The selected liposomal rhASM formulation significantly reduced the accumulated lyso-sphingomyelin in NPD-B fibroblasts by 71%, part of this effect was stimulated by the used lipids, compared to 55% when using the free rhASM enzyme. More importantly, the undesired extracellular degradation of sphingomyelin was reduced when using the selected liposomal rhASM by 61% relative to the free rhASM. The presented in vitro data indicate that the liposomal rhASM is effective and may provide a safer intervention than free rhASM.

Keywords: Acid sphingomyelinase; Enzyme replacement therapy; Liposome; Lysosomal storage disease; Niemann-Pick disease; Rare disease.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Ceramides / metabolism
  • Dose-Response Relationship, Drug
  • Fibroblasts / metabolism*
  • HEK293 Cells
  • Humans
  • Lipids / chemistry
  • Liposomes
  • Lysosomes / metabolism
  • Macrophages / metabolism*
  • Mice
  • RAW 264.7 Cells
  • Recombinant Proteins / administration & dosage*
  • Recombinant Proteins / metabolism
  • Sphingomyelin Phosphodiesterase / administration & dosage*
  • Sphingomyelin Phosphodiesterase / metabolism
  • Sphingomyelins / metabolism*


  • Ceramides
  • Lipids
  • Liposomes
  • Recombinant Proteins
  • Sphingomyelins
  • Sphingomyelin Phosphodiesterase
  • olipudase alfa