Enhanced neuroprotective activity of ophthalmic delivered nerve growth factor conjugated with cell penetrating peptide against optic nerve injury

Aims: Nerve growth factor is a well characterised neurotrophic factor that play a critical role in the survival, growth and differentiation of neurons both in central and peripheral nervous system. However, it is difficult for the conventional exogenous nerve growth factor administration delivery to the central nervous system due to the biological barrier in human bodies.Results: We validated a series of cell penetrating peptides and found that L-PenetraMax significantly enhanced the efficiency of recombinant human nerve growth factor entry into the rat retina. In the optic nerve crush mice model, eye drop administration of recombinant human nerve growth factor alone promoted retinal ganglion cell survival and axon regeneration at high dose, while the combination of recombinant human nerve growth factor with L-PenetraMax significantly enhanced the neuroprotective efficacy at lower dose, thus potentially enhancing the availability of recombinant human nerve growth factor eye drops in patients with optic neuropathy.Conclusions: This study provides the evidence that the noncovalent coadministration of recombinant human nerve growth factor with L-PenetraMax could be a potent strategy for the non-invasive and sustained ocular delivery of therapeutic proteins for improving the optic nerve injury.

Effect of Topical Recombinant Human Nerve Growth Factor on Corneal Epithelial Regeneration in Refractory Epithelial Keratopathy

PURPOSE

To report the effect of topical application of recombinant human nerve growth factor (rhNGF) eye drops on corneal epithelial regeneration in patients with refractory epitheliopathy.

METHODS

A retrospective chart review was conducted on patients treated with topical rhNGF for refractory epithelial keratopathy due to stage I neurotrophic keratitis (NK). Data regarding demographics and ocular/systemic past medical history was extracted from patient charts. Visual acuity and corneal staining scores were recorded at baseline and subsequent follow-up visits at 8 weeks and 3 months. Measurements from the worse eye were used to compare before and after treatment values.

RESULTS

We identified 14 patients (median age 68 years, 21% male) who received rhNGF treatment for refractory epithelial keratopathy. After an 8-week treatment with topical rhNGF, the median corneal staining score in the worse eye improved from 4 to 1 (p = 0.001). All patients showed at least one-grade improvement in corneal staining at 8 weeks, with sustained effect in seven patients at 3 months. A better response was observed in eyes with post-radiation epithelial keratopathy, LASIK, and Sjogren's disease. Those with chronic use of other topical treatments and uncontrolled diabetes mellitus demonstrated incomplete responses. Eight patients reported mild-to-moderate ocular discomfort from drop application that fully resolved after completion of treatment.

CONCLUSIONS

Topical rhNGF was effective and safe for refractory epithelial keratopathy in our small cohort, but sustained effects were seen only in certain etiologies for up to 3 months. Further studies are needed for optimal dosing and duration based on underlying causes.

Effect of recombinant human nerve growth factor treatment on corneal nerve regeneration in patients with neurotrophic keratopathy

Introduction

Neurotrophic Keratopathy (NK) is a neurodegenerative corneal disease that results in diminished corneal sensation. Previous studies have found that Cenegermin 0.002%, a recombinant human nerve growth factor (rhNGF), improves corneal epithelial healing in stage 2 and 3 NK patients. However, rhNGF effect on corneal sensation and nerve regeneration has not been well established. Thus, this study aims to analyze the effect of rhNGF on corneal nerve regeneration using in vivo confocal microscopy (IVCM) and on corneal sensitivity in NK patients.

Methods

This is a retrospective, longitudinal, case-control study that included patients with NK, treated with rhNGF for at least 4 weeks, with pre- and post-treatment IVCM images available for analysis. Chart reviews were conducted documenting prior medical and surgical history, clinical signs and symptoms, and corneal sensation using Cochet-Bonnet esthesiometry. Corneal nerve parameters were assessed by IVCM. Sex- and age-matched reference controls were selected from a database of healthy subjects for comparison.

Results

The study included 25 patients, with 22 (88%) stage 1, two (8%) stage 2, and 1 (4%) stage 3 NK patients, with a median age of 64 years (range: 30-93 years). Total, main, and branch nerve densities [median (range) in mm/mm2] were lower in the NK group pre-treatment [2.3 (0.0-21.1); 1.7 (0.0-13.0); 0.5 (0.0-10.2); respectively] vs. controls [22.3 (14.9-29.0); 10.1 (3.2-15.4); and 12.1 (6.2-18.4), (p < 0.0001 for all), respectively]. Post-treatment nerve densities increased compared to pre-treatment to 5.3 (0.0-19.4, p = 0.0083) for total, 3.5 (0.0-13.2, p = 0.0059) for main, and 2.0 (0.0-10.4, p = 0.0251) for branch nerves, but remained lower than controls (p < 0.0001 for all). Corneal sensation increased from 2.3 ± 1.1 cm pre-treatment to 4.1 ± 1.4 cm post-treatment (p = 0.001). Median best corrected visual acuity significantly increased following rhNGF treatment from 0.4 (0.0-1.6) to 0.12 (-0.1 to 1.6) (p = 0.007).

Conclusion

Patients with NK treated with at least 4 weeks of rhNGF, showed a significant increase in corneal nerve densities after treatment. A significant increase in corneal sensation, as well as best corrected visual acuity, was observed following treatment.

Clinical observation of recombinant human nerve growth factor in the treatment of neurotrophic keratitis

AIM

To characterize changes of corneal nerve morphology and tear indices in patients with neurotrophic keratitis (NK) treated with recombinant human nerve growth factor (rhNGF).

METHODS

In a prospective observational study, six patients (nine eyes) were locally treated with rhNGF. Visual acuity, corneal fluorescein staining score, the heights of the tear river, lipid layer thickness (LLT), tear ferning (TF) test, conjunctival impression cytology (CIC) examination, the densities of cornea subbasal nerve fibers were determined before and after treatment.

RESULTS

Compared with baseline, there was a significant difference in corneal fluorescence staining scores (P<0.01); all patient corneal epithelial defects recovered completely within 8wk, but there was no significant improvement in the height of the tear river (P=0.202). LLT was significantly increased when compared with baseline (P=0.042); however, the function of conjunctival goblet cells and mucin content did not significantly improve using the TF test and CIC examination (P=0.557, P=0.539). After 8wk of treatment, the average corneal subbasal nerve fiber density increased significantly (P<0.01), as did the number of corneal nerve fiber branches (P=0.001).

CONCLUSION

RhNGF can increase the density of corneal subbasal nerve fibers, promote the healing of persistent corneal epithelial defects and corneal ulcers in patients with NK, also improving tear function partially.

Efficacy of rhNGF-loaded amniotic membrane transplantation for rabbit corneal epithelial and nerve regeneration

AIM

To evaluate the efficacy of recombinant human nerve growth factor-loaded amniotic membrane (rhNGF-AM) on corneal epithelial and nerve regeneration in rabbit model.

METHODS

Freshly prepared human amniotic membrane (AM) were immersed into PBS buffer containing 100 or 500 µg/mL rhNGF for 15, 30, and 60min at 4°C. The in vitro release kinetics of rhNGF was measured with ELISA. For in vivo evaluation, the AM were immersed with 500 µg/mL rhNGF for 30min. Fifty-seven rabbits were selected to establish corneal epithelial defect model. In addition to the 19 rabbits in control group, 38 rabbits received AM transplantation with or without rhNGF after the removal of central epithelium. Corneal epithelial defect area, sub-epithelial nerve fiber density, corneal sensitivity, rhNGF contents in resident AM and corneas were measured after the surgery.

RESULTS

rhNGF was sustained release from the AM within 14d in vitro, with the positive correlation with initial immersion concentration. The immersion of AM in 500 µg/mL rhNGF for 30min achieved the most stable release within 14d. After transplantation in rabbit cornea, a high concentration of rhNGF in resident rhNGF-AM and cornea was maintained within 8d. Corneal epithelial healing, nerve fiber regeneration and the recovery of corneal sensitivity were significantly accelerated after the rhNGF-AM transplantation when compared to simple AM transplantation (all P<0.05).

CONCLUSION

Simple immersion of AM achieves the sustained release of rhNGF, and promotes corneal epithelial wound healing and nerve regeneration, as well as the recovery of corneal sensitivity in rabbit.

A case report of pediatric neurotrophic keratopathy in pontine tegmental cap dysplasia treated with cenegermin eye drops

RATIONALE

To report the management of recalcitrant neurotrophic keratopathy in a pediatric patient affected by pontine tegmental cap dysplasia (PTCD) using topical human recombinant nerve growth factor (hrNGF, Cenegermin 20 μg/ml). To the best of our knowledge the present case is one of the few described in patients with congenital NK treated with Cenegermin, and the first in a patient affected by PTCD.

PATIENT CONCERNS

A 9-year-old patient, affected by PTCD with bilateral cranial nerve V1 and VIII palsies, was referred to our hospital for visual disturbances and redness of the right eye due to persistent neurotrophic epithelial defect. The patient presented marked developmental delay, ataxia, bilateral hypoacusia, and bilateral corneal severe hypoaesthesia. Ocular history revealed multiple treatments in order to treat neurotrophic ulcer in the left eye. Four years later, he developed a persistent epithelial defect with corneal anesthesia in the right eye.

DIAGNOSES

The impaired trigeminal nerve function, due to the underlying congenital disease, led to the development of moderate NK (stage II) in the right eye and a mild NK (stage I) in the left eye.

INTERVENTIONS

Cenegermin 20 μg/ml eye-drop was administered in both eyes. Treatment was continued for 8 weeks. The patient was assessed after 4 and 8 week of treatment. At each follow-up visit, treatment efficacy and adverse events were evaluated.

OUTCOMES

The use of Cenegermin eye drops facilitated the remarkable resolution of the neurotrophic keratopathy and the improvement of corneal sensitivity in both eyes. No local or systemic adverse events were observed.

LESSONS

Topical Cenegermin 20 μg/ml was well-tolerated and may represent a valuable therapeutic option in the management of pediatric neurotrophic keratopathy.