Purchase this article with an account.
Barbara M Wirostko, Gina L Griffith, David O Zamora, MaryJane Rafii, Anthony James Johnson, Hee-Kyoung Lee; Sustained Delivery of rHGH via a Novel, Biodegradable, Hyaluronic Acid (HA) Polymer Film. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):262.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Treatments for chronic ocular diseases can require repeated and long-term drug administration. A cross-linked, thiolated, carboxymethyl HA (CMHA) matrix that can enable sustained release of proteins would enhance the efficacy and ease of administration of many such therapies. Drug release from the CMHA matrix has long been established in various non-ocular tissues. Our study demonstrates the ability to incorporate a protein - recombinant human growth hormone (rHGH) being developed for corneal wound healing - into the CMHA matrix and then release that protein in vitro and in vivo over time.
CMHA films containing rHGH (75, 150 and 300 µg/film) were molded (12 mg/ml of thiolated HA in a 1.5:1 thiol:acrylate ratio). To confirm successful incorporation and release of rHGH from the films/strips, o-phthaldialdehyde was used to monitor in vitro release of rHGH. Bioactivity of released rHGH was confirmed via human corneal epithelial cells (HCEC) proliferation assay (CyQuant). CMHA 150 µg/film (6 mm dried) were tested for in vivo release in 10 rabbits at the United States Army Institute for Surgical Research. Films either containing rHGH (n=5) or no rHGH (n=5) were re-hydrated in sterile buffered saline and placed in the left cul-de-sac. Right eyes (n=10) received no treatment and served as controls. Rabbits were monitored clinically daily and checked for strip retention. Tears were collected via capillary tube methodology prior to strip placement and on days 5, 8, and 14 post film placement. Tears were assayed for rHGH via ELISA.
In vitro assays yielded a dose response curve with total release proportional to dose load (300 µg film: 77% cumulative release until day 60; 150 µg : 67% cumulative until day 60; 75 µg: 57% cumulative release until day 60). Bioactive rHGH released from films in vitro was confirmed by HCEC proliferation.<br /> Tear samples taken from eyes treated with rHGH films contained rHGH levels as high as 303 ng/ml at day 5. rHGH tear levels decreased over time out to day 14. No rHGH was detected in control tears.
CMHA films are capable of delivering rHGH, in a sustained release manner in vitro and in vivo over the course of days to months. These data enable further development of other protein drug delivery products using the CMHA matrix thus reducing treatment frequency and potentially enhancing therapeutic efficacy in a variety of ocular diseases.
This PDF is available to Subscribers Only