title: Beta Hairpin Peptide Hydrogels as an Injectable Solid Vehicle for Neurotrophic Growth Factor Delivery.
abstract: There is intense interest in developing novel methods for the sustained delivery of low levels of clinical therapeutics. MAX8 is a peptide-based beta-hairpin hydrogel that has unique shear thinning properties that allow for immediate rehealing after the removal of shear forces, making MAX8 an excellent candidate for injectable drug delivery at a localized injury site. The current studies examined the feasibility of using MAX8 as a delivery system for nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF), two neurotrophic growth factors currently used in experimental treatments of spinal cord injuries. Experiments determined that encapsulation of NGF and BDNF within MAX8 did not negatively impact gel formation or rehealing and that shear thinning did not result in immediate growth factor release. ELISA, microscopy, rheology, and Western blotting experiments collectively demonstrate the functional capabilities of the therapeutic-loaded hydrogels to (i) maintain a protective environment against in vitro degradation of encapsulated therapeutics for at least 28 days; and (ii) allow for sustained release of NGF and BDGF capable of initiating neurite-like extensions of PC12 cells, most likely due to NGF/BDGF signaling pathways. Importantly, while the 21 day release profiles could be tuned by adjusting the MAX8 hydrogel concentration, the initial shear thinning of the hydrogel (e.g., during injection) does not induce significant premature loss of the encapsulated therapeutic, most likely due to effective trapping of growth factors within structurally robust domains that are maintained during the application of shear forces. Together, our data suggests that MAX8 allows for greater dosage control and sustained therapeutic growth factor delivery, potentially alleviating side effects and improving the efficacy of current therapies.
authors.forename: Stephan
authors.initials: S
authors.lastname: Lindsey
authors.forename: Joseph H
authors.initials: JH
authors.lastname: Piatt
authors.affiliation: Biomedical Engineering Graduate Program, University of Delaware , Newark, Delaware 19716, United States.
authors.forename: Peter
authors.initials: P
authors.lastname: Worthington
authors.affiliation: Center for Cancer Research, NCI , Frederick, Maryland 21702, United States.
authors.forename: Cem
authors.initials: C
authors.lastname: Sönmez
authors.affiliation: Department of Materials Science and Engineering, University of Delaware , Newark, Delaware 19716, United States.
authors.forename: Sameer
authors.initials: S
authors.lastname: Satheye
authors.affiliation: Center for Cancer Research, NCI , Frederick, Maryland 21702, United States.
authors.forename: Joel P
authors.initials: JP
authors.lastname: Schneider
authors.affiliation: Department of Materials Science and Engineering, University of Delaware , Newark, Delaware 19716, United States.
authors.forename: Darrin J
authors.initials: DJ
authors.lastname: Pochan
authors.forename: Sigrid A
authors.initials: SA
authors.lastname: Langhans
mesh_terms: D000818:Animals; D004337:Drug Carriers / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D020100:Hydrogels / Q000737:chemistry / Q000494:pharmacology; D020932:Nerve Growth Factor / Q000737:chemistry / Q000494:pharmacology; D016716:PC12 Cells; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology; D051381:Rats
chemical_list: D004337:Drug Carriers; D020100:Hydrogels; D010455:Peptides; D020932:Nerve Growth Factor