Scavenger receptor block as strategy for the identification of bone marrow homing phages by panning in vivo random peptide phage displayed libraries.
Surface molecules exclusively expressed by cells of the bone marrow (BM) are candidate targets for delivering therapeutic agents to this tissue. To identify ligands specific for the BM, we performed a series of pannings in vivo with random peptide phage displayed libraries (RPPDL). We could show that phages bind to bone marrow endothelium (BME) independently of the peptide insert, suggesting that the BM, similarly to spleen and liver, is part of the reticulo-endothelial system (RES). Furthermore, this strong "natural" affinity to the BME was abrogated by polyanions, indicating that phage trapping by this endothelium is mediated by scavenger receptors (SR). To circumvent interference by SR, polyinosinic acid was administered before phage panning in vivo. This led to the identification of a consensus motif that confers binding specificity for a subpopulation of hemopoietic marrow cells. Thus, SR inhibition, by avoiding phage trapping by the endothelium, seems to allow phage particles to extravasate and reach parenchymal cells. Accordingly, this panning strategy in vivo may be useful for the identification of targeting motifs specific for cells located in the extravascular space of various tissues.
Gene Therapy Laboratory, Department of Clinical Research and Department of Urology, University of Bern, Sahli-Haus 2, Inselspital, Bern, Switzerland.
Anita N
AN
Finger
Marco
M
Bisoffi
Antoinette
A
Wetterwald
Elsbeth
E
Gautschi
Ulrike
U
Hohenfeld
Irena
I
Klima
Beda M
BM
Stadler
Luca
L
Mazzucchelli
George N
GN
Thalmann
Marco G
MG
Cecchini
D020816:Amino Acid Motifs; D000818:Animals; D017104:Bacteriophage M13 / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D001854:Bone Marrow Cells / Q000378:metabolism* / Q000821:virology; D002460:Cell Line; D007275:Injections, Intravenous; D008099:Liver / Q000378:metabolism / Q000821:virology; D008565:Membrane Proteins; D051379:Mice; D008807:Mice, Inbred BALB C; D012157:Mononuclear Phagocyte System / Q000378:metabolism; D010446:Peptide Fragments / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism; D019151:Peptide Library; D011061:Poly A / Q000008:administration & dosage / Q000378:metabolism; D011069:Poly I / Q000008:administration & dosage / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D011971:Receptors, Immunologic / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; D051122:Scavenger Receptors, Class B; D013154:Spleen / Q000378:metabolism / Q000821:virology
D008565:Membrane Proteins; D010446:Peptide Fragments; D019151:Peptide Library; D012333:RNA, Messenger; D011971:Receptors, Immunologic; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; C454739:Scarb1 protein, mouse; D051122:Scavenger Receptors, Class B; D011061:Poly A; D011069:Poly I