Neurotrophin-conjugated nanoparticles prevent retina damage induced by oxidative stress

Abstract

Glaucoma and other optic neuropathies are characterized by a loss of retinal ganglion cells (RGCs), a cell layer located in the posterior eye segment. Several preclinical studies demonstrate that neurotrophins (NTs) prevent RGC loss. However, NTs are rarely investigated in the clinic due to various issues, such as difficulties in reaching the retina, the very short half-life of NTs, and the need for multiple injections. We demonstrate that NTs can be conjugated to magnetic nanoparticles (MNPs), which act as smart drug carriers. This combines the advantages of the self-localization of the drug in the retina and drug protection from fast degradation. We tested the nerve growth factor and brain-derived neurotrophic factor by comparing the neuroprotection of free versus conjugated proteins in a model of RGC loss induced by oxidative stress. Histological data demonstrated that the conjugated proteins totally prevented RGC loss, in sharp contrast to the equivalent dose of free proteins, which had no effect. The overall data suggest that the nanoscale MNP-protein hybrid is an excellent tool in implementing ocular drug delivery strategies for neuroprotection and therapy.Electronic supplementary materialThe online version of this article (10.1007/s00018-017-2691-x) contains supplementary material, which is available to authorized users.

Association of the Somatostatin Analog Octreotide With Magnetic Nanoparticles for Intraocular Delivery: A Possible Approach for the Treatment of Diabetic Retinopathy

“…Our data show that MNP-OCT preferentially localize to the RPE following intravitreal injection in a mouse eye, similar to previous findings in Xenopus embryos and zebrafish larvae obtained with unconjugated MNPs or with MNPs conjugated with neurotrophins (Giannaccini et al, 2014(Giannaccini et al, , 2018. In particular, our observations are consistent with a migration of the MNP-OCT from the vitreous chamber toward the retina, and from the inner to the outer retina and into the RPE, in a process that is completed within the first 24 h, although high resolution TEM images documented that small quantities of MNP-OCT were still diffusing through the retina at this time.…”

“…Of note, the anti-apoptotic effect of MNP-OCT in OS-treated retinal explants was still detected at the lowest dose employed in these experiments, therefore the possibility exists that MNP-OCT may have efficacy even at lower concentrations than 0.001 µM. These observations are consistent with similar results obtained in retinas of OS-treated zebrafish larvae (Giannaccini et al, 2018). The increased efficacy of MNP-OCT is likely to be due to the fact that the conjugation of the drug to MNPs increases its stability, thus improving its activity.…”

“…Their hydrodynamic diameter is 50 nm (product information sheet). These MNPs are characterized by a polydispersity index of 0.337 ± 0.022, and a negative Z potential (-38.72 ± 2.14 mV) due to their surface functionalization with carboxylic groups (Giannaccini et al, 2018). The nanoparticles were covalently functionalized with OCT (Abcam, Cambridge, United Kingdom) using an MNP/protein ratio of 3.5:1 w/w via EDC chemistry, as previously described (Pinkernelle et al, 2015;Giannaccini et al, 2017a,b).…”

“…Indeed, it has been shown that the choice of the functionalization method is crucial for the maintenance of the drug bioactivity (Pinkernelle et al, 2015). For instance, the covalent binding of BDNF or VEGF to MNPs does not affect drug bioactivity, while NGF binding does, as demonstrated in retinas of zebrafish larvae (Giannaccini et al, 2018). We compared the bioactivity of MNP-OCT with that of free OCT, showing that, after binding with MNPs, OCT maintains its antiangiogenic potential inhibiting the VEGF-driven activation of HRECs.…”

“…Indeed, intraocularly injected MNPs have been shown to enter the retina rapidly and persistently localize within the retinal pigment epithelium (RPE) in Xenopus and zebrafish without inducing any tissue damage (Giannaccini et al, 2014). Importantly, MNPs have been demonstrated to be effective in loading and delivering molecules such as brain derived neurotrophic factor (BDNF) and nerve growth factor (NGF) to zebrafish eyes with an increase of their effectiveness in preventing oxidative retinal damage (Giannaccini et al, 2018). Here we tested the feasibility of using MNP-bound OCT (MNP-OCT) for treatment of DR.…”