title: Differentially cleaving peptides as a strategy for controlled drug release in human retinal pigment epithelial cells.
abstract: Currently, drug delivery to the posterior eye segment relies on intravitreal injections of therapeutics. This approach requires frequent injections and does not guarantee drug delivery to intracellular targets. Controlled release systems and nanoparticles are being investigated to mitigate these challenges but most of these approaches lack translational success to the clinics. In our present study, we report a peptide-based delivery system that utilizes enzyme assisted cleavable linkers to release conjugated cargo within the retinal pigment epithelial (RPE) cells. Peptide linkers with differential cleavage rates were developed and tested in the vitreous humor, RPE cell homogenates and intact RPE cells. Selected peptide linkers were conjugated to cell penetrating peptides and d-peptide cargoes. The peptide-based delivery systems were non-toxic to the RPE cells, chemically stable in porcine vitreous and delivered cargo prototypes (hydrophobic & hydrophilic) to the RPE cells. Importantly, we show quantitatively with LC/MS analytics that the intracellular cargo release is controlled by the sequence of the peptide linker. The controlled cleavage of the peptide linkers is not only a useful strategy for intracellular drug delivery to the RPE targets but might also be useful in utilizing the RPE cells as mediators of drug delivery to intracellular targets and surrounding tissues (such as neural retina and choroid).
authors.affiliation: Centre for Drug Research, Division of Pharmaceutical Biosciences, University of Helsinki, Helsinki, Finland. Electronic address: madhushree.bhattacharya@helsinki.fi.
authors.forename: Madhushree
authors.initials: M
authors.lastname: Bhattacharya
authors.affiliation: Centre for Drug Research, Division of Pharmaceutical Biosciences, University of Helsinki, Helsinki, Finland.
authors.forename: Sanjay
authors.initials: S
authors.lastname: Sarkhel
authors.affiliation: Centre for Drug Research, Division of Pharmaceutical Biosciences, University of Helsinki, Helsinki, Finland.
authors.forename: Jonne
authors.initials: J
authors.lastname: Peltoniemi
authors.affiliation: Peptide Protein Research Ltd, Hampshire, England, United Kingdom.
authors.forename: Robert
authors.initials: R
authors.lastname: Broadbridge
authors.affiliation: School of Pharmacy, University of Eastern Finland, Kuopio, Finland.
authors.forename: Marjo
authors.initials: M
authors.lastname: Tuomainen
authors.affiliation: School of Pharmacy, University of Eastern Finland, Kuopio, Finland.
authors.forename: Seppo
authors.initials: S
authors.lastname: Auriola
authors.affiliation: Centre for Drug Research, Division of Pharmaceutical Biosciences, University of Helsinki, Helsinki, Finland; School of Pharmacy, University of Eastern Finland, Kuopio, Finland.
authors.forename: Arto
authors.initials: A
authors.lastname: Urtti
mesh_terms: D000818:Animals; D002402:Cathepsin D / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival; D016503:Drug Delivery Systems; D004847:Epithelial Cells / Q000378:metabolism*; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D058449:Intravitreal Injections; D053758:Nanoparticles; D010455:Peptides / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D010857:Pigment Epithelium of Eye / Q000166:cytology / Q000378:metabolism*; D012168:Retinal Pigments / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013552:Swine; D014018:Tissue Distribution; D014822:Vitreous Body / Q000378:metabolism
chemical_list: D010455:Peptides; D012168:Retinal Pigments; D002402:Cathepsin D
keywords: Conjugation; Drug delivery; Drug targeting; Ocular therapeutics; Peptide; Retina; Retinal pigment epithelium