Intravitreal fluocinolone acetonide 0.19 mg (Iluvien®) for the treatment of uveitic macular edema: 2-year follow-up of 20 patients.

PURPOSE: To evaluate intravitreal 0.19 mg fluocinolone acetonide implant (FAi) (Iluvien®) for the treatment of chronic non-infectious uveitis with associated cystoid macular edema (CME). METHODS: A retrospective review of medical reports from a single Danish tertiary centre including 20 patients (20 eyes), treated with 0.19 mg FAi for non-infectious uveitic CME. The primary endpoints were change in best corrected visual acuity (BCVA) and central retinal thickness (CRT). The secondary endpoints were recurrence rate, change in systemic treatment, and intraocular pressure (IOP). RESULTS: Mean follow-up of the 20 eyes was 2.3 ± 1.1 years. BCVA improved at 6 (p = 0.13), 12 (p = 0.05), 18 (p = 0.03), and 24 months and CRT decreased at 6 (p = 0.004), 12 (p = 0.006), 18, and 24 months after 0.19 mg FAi. Within 18 months after implantation, four of 14 patients (28.6%) relapsed. Three of five patients discontinued systemic corticosteroids within 4 months and one patient continued with reduced dose. Five of 10 patients receiving disease-modifying antirheumatic drugs (DMARDs) at time of implantation discontinued within 1 year. No patients started new systemic treatment. Eight eyes were treated with topical IOP-lowering medication at the time of implantation, of these two later underwent trabeculectomy. There were no complications associated with previous glaucoma surgery. CONCLUSION: This long-term follow-up study showed that intravitreal treatment with 0.19 mg FAi should be considered in the treatment of chronic non-infectious uveitic CME in selected patients. This treatment is safe even in selected glaucoma patients and may offer reduction or cessation of local or systemic anti-inflammatory treatment.

Increasing metabolic variability increases the risk for vitrectomy in proliferative diabetic retinopathy.

PURPOSE: Proliferative diabetic retinopathy (PDR) can be treated by retinal photocoagulation, but in some cases, the treatment is initiated too late or is insufficient so that the disease advances to a stage requiring vitrectomy. There is a need to identify risk factors that can predict if patients with PDR will develop complications in need for vitrectomy. METHODS: Survival analysis with death as competing risk was used to study systemic risk factors for PDR progression to a complication in need for vitrectomy in right eyes of all 1288 diabetic patients from the Aarhus area, Denmark, who had developed proliferative retinopathy in the right eye during the 25 years period from 1 July 1994 until 1 July 2019. RESULTS: The overall cumulative incidence of reaching a vitrectomy end point in the right eye was 24.1% (n = 311). In 9.3% (n = 120) of the patients where vitrectomy had been performed together with the first photocoagulation, the age of onset of diabetes was significantly higher (p < 0.0001), the diabetes duration longer (p < 0.035) and BMI higher (p < 0.01) than in the patients who had been vitrectomized later than the first photocoagulation. The risk for vitrectomy was significantly increased by high variability of HbA1c before the development of PDR (p < 0.0001), but not by other parameters known to increase the risk for developing PDR. CONCLUSION: Increasing variability of HbA1c before the development of PDR increases the risk for progression to a complication in need of vitrectomy. The need for vitrectomy is unaffected by other risk factors known to increase the risk for developing PDR.

Continuous MPTP intoxication in the Göttingen minipig results in chronic parkinsonian deficits.

Parkinson's disease (PD) is a common neurodegenerative disorder, resulting from progressive loss of dopaminergic neurons in the substantia nigra pars compacta (SNc). Neuroprotective therapies in PD are still not available, perhaps because animal models do not imitate the chronic and progressive nature of the clinical state of PD. To address this, we performed a feasibility study aimed at establishing a chronic non-primate large animal PD model in Göttingen minipigs based on continuous infusion of the neurotoxin 1-methyl-4-phenyl­1,2,3,6-tetrahydropyridine (MPTP). Twelve female Göttingen minipigs were divided into groups of 2-4 animals and implanted with infusion pumps for continuous intramuscular MPTP delivery of 4-24 mg MPTP/day for 11 weeks. The animals showed parkinsonian symptoms with bradykinesia, rigidity, coordination and chewing difficulties. Symptoms were stable in the 12 and 18 mg MPTP/day groups, whereas the remaining groups showed partial or full behavioral recovery. Digital gait analysis, high performance liquid chromatography (HPLC) measurements and stereological counts of tyrosine hydroxylase-positive (TH+) neurons in the SNc revealed a dose-related decrease in gait velocity, striatal metabolite levels and neuron numbers with increasing doses of MPTP. No neuronal inclusions were observed, but alpha-synuclein staining intensified with increased cumulative MPTP dosages. We conclude that this large-animal model of chronic MPTP administration in Göttingen minipigs shows trends of stable parkinsonian deficits at 18 mg MPTP/day in all modalities examined. This PD model shares many of the characteristics seen in patients and, although preliminary, holds considerable promise for future pre-clinical trials of neuroprotective therapies.

Direct MRI-guided stereotaxic viral mediated gene transfer of alpha-synuclein in the Göttingen minipig CNS.

The aim was to establish a non-primate large animal PD model by lentiviral vector mediated mutant alpha-synuclein overexpression in the substantia nigra. Lentivirus encoding A53T alpha-synuclein (6 x 2.5 µl) was stereotaxically injected into the substantia nigra of six adult female Göttingen minipigs. Contralateral control injections encoding enhanced green fluorescent protein (EGFP) were performed. Gait-analysis was performed pre- and postoperatively. PCR of the transgenes and immunohistochemical staining against alpha-synuclein, EGFP, GFAP and TH was performed after 20 weeks. Gait analysis revealed a significant increase in step length and height, and a decrease in the double stand phase. PCR verified the mesencephalic presence of transgenes. IHC analysis showed alpha-synuclein expression in nigral neurons, around the injection tract and in related nigrostriatal projections. The alpha-synuclein positive neurons appeared swollen and vacuolated, in contrast to the EGFP-injected control side. To transduct all nigrostriatal cells with few microinjections, wider dissemination of the transgene must be achieved.

Direct gene transfer in the Gottingen minipig CNS using stereotaxic lentiviral microinjections.

We aim to induce direct viral mediated gene transfer in the substantia nigra (SN) of the Gottingen minipig using MRI guided stereotaxic injections of lentiviral vectors encoding enhanced green fluorescent protein (EGFP). Nine female Gottingen minipigs were injected unilaterally into the SN with 6 per 2.5 microliters lentivirus capable of transducing cells and mediating expression of recombinant EGFP. The animals were euthanized after four (n=3) or twenty weeks (n=6). Fresh brain tissue from three animals was used for PCR. The remaining six brains were cryo- or paraffin-sectioned for fluorescence, Nissl-, and immunohistochemical EGFP visualization. EGFP was seen in nigral neurons, axons, glial cells, endothelial cells, and in nigral fibers targeting the striatum. PCR-based detection confirmed the presence of the transgene in SN, whereas all other examined brain areas were negative, indicating that the immunohistochemically detected EGFP in the striatum derived from transfected nigral cells.

The substantia nigra pars compacta of the Göttingen minipig: an anatomical and stereological study.

Parkinson disease (PD) is a neurodegenerative disorder resulting from progressive loss of dopaminergic neurons in the substantia nigra pars compacta (SNc). Despite advances in medical and surgical therapies, many PD patients experience progression of their symptoms and medical side effects over time. To explore new treatments, new animal models mimicking the progressive PD nature are needed. The pig is well suited for this purpose with its large gyrated brain, sensitive to the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The objective of this study was to provide the anatomical foundation for such a model, describing in detail the SNc in normal Göttingen minipigs and estimating the volume and total number of tyrosine hydroxylase (TH)-positive neurons. The brain stems of 6 Göttingen minipigs were paraffin embedded and serially cut before Nissl staining and immunohistochemical visualization of TH. The volume of the SNc and the total number of TH-positive neurons were estimated by design-based stereology. The substantia nigra was located at the dorsal rim of the crus cerebri extending throughout the mesencephalon. A dorsal pars compacta and a ventral pars reticulata were demonstrated. The SNc merged with the ventral tegmental area medially and the retro-rubral field dorsocaudolaterally. The total number of TH-positive neurons in the SNc unilaterally was estimated to 80,700 [74,100;87,300], and the volume estimate was 26.4 mm(3) [25.0;27.8]. We conclude that the anatomy of the SNc in the Göttingen minipig corresponds well with that of higher primates, and is well suited for further studies aimed at optimizing this non-primate large animal model for PD.

MRI protocol for in vivo visualization of the Göttingen minipig brain improves targeting in experimental functional neurosurgery.

BACKGROUND: The Göttingen minipig is increasingly used as an animal model in experimental neuroscience as a much needed alternative to non-human primates. Accurate spatial targeting in this species in vivo is challenging, and most clinically available magnetic resonance imaging (MRI) protocols do not provide sufficient spatial resolution for this purpose. Thus, the aim of this study was to develop an in vivo pre-operative MRI protocol allowing direct visualization of individual nuclei of major interest in the minipig brain. MATERIALS AND METHODS: Three Göttingen minipigs underwent MRI using an inversion-recovery fast spin-echo sequence that was optimized with regards to the following parameters: inversion time, relaxation time, echo time and spatial and temporal resolution, giving a scan duration acceptable for the tight schedule usually employed in a neurosurgical procedure. The most optimal pulse sequence was applied in 8 Göttingen minipigs and the anatomical structures were identified. RESULTS AND CONCLUSION: High-resolution images with excellent contrast were acquired, presenting negligible geometric distortions. Minor flow artifacts from the large neck vessels generated the most prominent artifact. Determination of coordinates necessary in experimental neurosurgery in the Göttingen minipig was considerably improved with this MRI protocol.