title: Acidic nanoparticles are trafficked to lysosomes and restore an acidic lysosomal pH and degradative function to compromised ARPE-19 cells.
abstract: Lysosomal enzymes function optimally in acidic environments, and elevation of lysosomal pH can impede their ability to degrade material delivered to lysosomes through autophagy or phagocytosis. We hypothesize that abnormal lysosomal pH is a key aspect in diseases of accumulation and that restoring lysosomal pH will improve cell function. The propensity of nanoparticles to end up in the lysosome makes them an ideal method of delivering drugs to lysosomes. This study asked whether acidic nanoparticles could traffic to lysosomes, lower lysosomal pH and enhance lysosomal degradation by the cultured human retinal pigmented epithelial cell line ARPE-19. Acidic nanoparticles composed of poly (DL-lactide-co-glycolide) (PLGA) 502 H, PLGA 503 H and poly (DL-lactide) (PLA) colocalized to lysosomes of ARPE-19 cells within 60 min. PLGA 503 H and PLA lowered lysosomal pH in cells compromised by the alkalinizing agent chloroquine when measured 1 hr. after treatment, with acidification still observed 12 days later. PLA enhanced binding of Bodipy-pepstatin-A to the active site of cathepsin D in compromised cells. PLA also reduced the cellular levels of opsin and the lipofuscin-like autofluorescence associated with photoreceptor outer segments. These observations suggest the acidification produced by the nanoparticles was functionally effective. In summary, acid nanoparticles lead to a rapid and sustained lowering of lysosomal pH and improved degradative activity.
authors.affiliation: Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Gabriel C
authors.initials: GC
authors.lastname: Baltazar
authors.forename: Sonia
authors.initials: S
authors.lastname: Guha
authors.forename: Wennan
authors.initials: W
authors.lastname: Lu
authors.forename: Jason
authors.initials: J
authors.lastname: Lim
authors.forename: Kathleen
authors.initials: K
authors.lastname: Boesze-Battaglia
authors.forename: Alan M
authors.initials: AM
authors.lastname: Laties
authors.forename: Puneet
authors.initials: P
authors.lastname: Tyagi
authors.forename: Uday B
authors.initials: UB
authors.lastname: Kompella
authors.forename: Claire H
authors.initials: CH
authors.lastname: Mitchell
mesh_terms: D000818:Animals; D001896:Boron Compounds / Q000737:chemistry; D020134:Catalytic Domain; D002402:Cathepsin D / Q000737:chemistry; D002417:Cattle; D002460:Cell Line; D002478:Cells, Cultured; D002738:Chloroquine / Q000737:chemistry; D005434:Flow Cytometry / Q000379:methods; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015151:Immunoblotting; D019344:Lactic Acid / Q000737:chemistry; D008062:Lipofuscin / Q000737:chemistry; D008247:Lysosomes / Q000378:metabolism*; D053758:Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*; D055355:Opsins / Q000737:chemistry; D010436:Pepstatins / Q000737:chemistry; D010587:Phagocytosis; D011100:Polyglycolic Acid / Q000737:chemistry; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000737:chemistry; D012160:Retina / Q000166:cytology
chemical_list: C095489:4,4-difluoro-4-bora-3a,4a-diaza-s-indacene; D001896:Boron Compounds; D008062:Lipofuscin; D055355:Opsins; D010436:Pepstatins; D011108:Polymers; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D002738:Chloroquine; D002402:Cathepsin D; C031375:pepstatin