Mannosereceptortargetingbymannosylatedliposomeshasbeendemonstratedforavarietyofmannosylatedlipidconjugatesinavarietyofliposomemorphologiesandcompositionsinseveraldifferent invitro and invivo models.Thereareseveralpublicationsusingahydrophobicderivativeofmannose(4-aminophenylα-D-mannopyranoside) ratherthanusingamannosylatedlipidinClodronateliposomes.Thisismainlyduetothehighcostandcomplexityofsynthesizingandconjugatingmannosetolipid. 4-aminophenylα-D-mannopyranosideiscommerciallyavailableandfarlessexpensivethansynthesizingmannoseconjugatedlipid.

Whymannose?Mannoseisoneofthecarbohydratecomponentsofmanybacterialandviralcellsurfaces;therefore,theever-efficient,highlyredundantimmunesystemhasevolvedmultiplemechanismsforidentifyingpathogensbasedonmannoserecognition.Theanimalandplantkingdomslikewiseutilizecarbohydraterecognitionsignalingmechanismsincludingmannoseresidues.Manypublicationsevaluateothercarbohydratesastargetingmechanismsforvariouscelltypes,howevermannosetargetingtophagocytesappearstobeoneofthemorespecificmechanismsidentifiedtodate.Mammaliancellsurfaceidentificationmoleculesbasedonmannosebinding,suchastheICAMfamilyofleukocyteadhesionmolecules,targettheSIGNfamilyofmannosereceptorstoaccomplishself-recognition invivo.

Awell-knownandcitedstudybyUmezawa&Eto[1]demonstratesthatliposomescontainingaminophenylmannosideweremostefficientlyincorporatedintothemousebrainacrossthebloodbrainbarrier.TherADIolabeledliposomesbearingaminophenyl