Comparative study of GDNF delivery systems for the CNS: polymer rods, encapsulated cells, and lentiviral vectors

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Abstract

Glial cell line-derived neurotrophic factor (GDNF) holds great promise for the treatment of Parkinson’s disease. In humans, its intracerebroventricular administration leads to limiting side effects. Direct parenchymal delivery using mechanical means, or cell and gene therapy represent potential alternatives. In the present study, a representative of each of these three approaches, i.e. polymer rods, genetically modified encapsulated cells and lentiviral vectors was analyzed for its ability to release GDNF in the striatum of rats. One week post-surgery, GDNF was detected over a distance of 4 mm with all three methods. At 4 weeks GDNF staining diminished with rods and to a lesser extent with encapsulated cells, whereas it increased with lentiviral vectors. Nanogram range of GDNF was measured with all methods at 1 week. At 4 weeks, GDNF levels decreased significantly with rods, whereas they remained stable with encapsulated cells and lentiviral vectors. We conclude that all three methods investigated allow striatal delivery of GDNF, but the time during which it needs to be released will determine the approach chosen for clinical application.

Introduction

Neurodegenerative disorders of the central nervous system (CNS) are characterized by a selective and progressive degeneration of neuronal subpopulations leading to severe debilitating clinical symptoms. Current treatments consist mainly in symptomatic therapies with no effect on the onset or disease progression. Efforts are thus being made to develop neuroprotection or even neuroregenerative strategies. Neurotrophic factors hold the greatest promise to achieve this goal.

Neurotrophic factors (NTFs) are polypeptides known to promote growth, survival and differentiation of neurons during development, as well as plasticity and structural integrity of the adult nervous system. These proteins have demonstrated potent neuroprotective effects on various neuronal populations in experimental models of neurodegenerative diseases, such as nerve growth factor (NGF) for Alzheimer’s disease (AD), glial cell line-derived neurotrophic factor (GDNF) for Parkinson’s disease (PD), or ciliary neurotrophic factor (CNTF) for Huntington’s disease (HD) [1], [2]. Several clinical trials have been conducted with each of these factors, so far, however, without success. Part of the problems may be related to inefficient delivery technique.

The CNS delivery of NTFs is limited by factors such as (i) their inability to cross the blood–brain-barrier, (ii) their poor stability in a fluid environment, (iii) their limited diffusion through brain parenchyma, and (iv) the side-effects associated with binding to extra-target receptors [3], [4]. Intracerebroventricular (ICV) administration eliminates the need to bypass the blood–brain-barrier. Poor diffusion within the brain parenchyma [5], [6] and occurrence of severe side-effects limit, however, its applicability. Excruciating pain was indeed described with the ICV administration of NGF in AD patients [7], [8]; weight loss, nausea and abnormal sexual behavior was reported with the ICV administration of GDNF in PD patients [9]. In contrast, animal experiments have shown that direct parenchymal administration dramatically reduces the occurrence of side-effects reported with ICV application [5], [10]. These observations emphasize the need for localized, sustained delivery of these molecules in specific nuclei of the CNS.

Direct localized CNS delivery is achievable either by mechanical means, or by cell or gene therapy. In the context of this work, we have chosen to compare a representative of each of the three approaches for the intrastriatal delivery of GDNF, a promising trophic factor for the treatment of PD, and deduct the relative advantages/disadvantages of the three delivery techniques.

Section snippets

GDNF-releasing polymer rods

Ethylene-vinyl acetate copolymer (EVA; Elvax, Dupont, Wilmington, USA) was cleaned by 20 washes in absolute ethanol followed by 20 washes in sterile distilled water, and finally dried under a mild vacuum. Bovine serum albumin (BSA; Sigma, Buchs, Switzerland) was sieved to a size <37 μm using scrynel PET33HC meshes (PolyLabo). A 10% (w/v) solution of purified EVA in methylene chloride solvent was prepared with 23% BSA (w/w total) and 1% recombinant human GDNF (Amgen) (w/w total), vortexed and

Diffusion pattern of GDNF in the striatum

One and 4 weeks following the implantation of polymer rods or hollow fibers, and the injection of lentiviral vectors into the rat striatum, immunohistochemical detection of hGDNF was performed to characterize the diffusion of the NTF throughout this structure (Fig. 1). One week post-surgery, GDNF staining was present over a maximal distance of 4 mm in the three groups, which almost corresponds to the entire striatum volume according to the rat brain atlas of Paxinos and Watson [16] (Fig. 1A–C).

Discussion

In the present study, we have compared the efficiency of three different methods for delivery of the neurotrophic factor GDNF in the brain parenchyma of adult rats. Polymer rods, encapsulated cells and lentiviral vectors enable the continuous and localized expression of significant amounts of GDNF in the striatum. Although the diffusion pattern of GDNF was approximately identical with the three approaches at 1 week post-surgery, results of the 4-week time point suggest that polymer rods are

Conclusion

The present work reveals the efficiency of three different delivery methods in providing a significant amount of GDNF in the rat striatum. These data open interesting perspectives for the treatment of neurodegenerative diseases. The dose and the time during which GDNF needs to be administered, i.e. more detailed pharmacokinetics for the administration of this trophic factor in the CNS will require further investigations to determine which one of these approaches would be particularly relevant

Acknowledgements

The authors thank Vivianne Padrun, Fabienne Pidoux, Maria Rey, Laurence Winkel and Christel Sadeghi for expert technical assistance. This work was partially supported by the Swiss National Science Foundation and the 5th European Framework Program “Neuroget”.

References (33)

  • F. Hefti

    Pharmacology of neurotrophic factors

    Annu. Rev. Pharmacol. Toxicol.

    (1997)
  • M.F. Haller et al.

    Localized delivery of proteins in the brain: can transport be customized?

    Pharm. Res.

    (1998)
  • J.K. Morse et al.

    Brain-derived neurotrophic factor (BDNF) prevents the degeneration of medial septal cholinergic neurons following fimbria transection

    J. Neurosci.

    (1993)
  • L. Olson et al.

    Nerve growth factor affects 11C-nicotine binding, blood flow, EEG, and verbal episodic memory in an Alzheimer patient (case report)

    J. Neural Transm. Park. Dis. Dement. Sect.

    (1992)
  • M. Eriksdotter Jonhagen et al.

    Intracerebroventricular infusion of nerve growth factor in three patients with Alzheimer’s disease

    Dement. Geriatr. Cogn. Disord.

    (1998)
  • J.H. Kordower et al.

    Clinicopathological findings following intraventricular glial-derived neurotrophic factor treatment in a patient with Parkinson’s disease

    Ann. Neurol.

    (1999)
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