Effects of Subtenon-injected Autologous Platelet-rich Plasma on Visual Functions in Eyes With Retinitis Pigmentosa (PRP)

Purpose One of the main reasons for apoptosis and dormant cell phases in degenerative retinal diseases such as retinitis pigmentosa (RP) is growth factor withdrawal in the cellular microenvironment. Growth factors and neurotrophins can significantly slow down retinal degeneration and cell death in animal models. One possible source of autologous growth factors is platelet-richplasma.The purpose of this study was to determine if subtenon injections of autologous platelet-rich plasma (aPRP) can have beneficial effects on visual function in RP patients by reactivating dormant photoreceptors.

Study Overview

• Status: Completed
• Conditions: Retinitis Pigmentosa
• Intervention / Treatment: Biological: Platelet rich plasma

Detailed Description

More than 240 genetic mutations are involved in inherited retinal dystrophies, which constitute an overlapping group of genetic and clinical heterogeneous disorders. Retinitis pigmentosa (RP) is a heterogeneous genetic disorder (autosomal dominant, autosomal recessive, X-linked, or sporadic cases from spontaneous mutations) characterized by the progressive devolution of the retina and affecting 1/3000- 8000 people worldwide. Symptoms include generally diminishing visual fields starting in the mid-periphery and advancing toward the fovea, ultimately leading to visual impairment and blindness with waxy-colored optic atrophy. RP is also described as rod-cone dystrophy because of the primary degeneration of rods along with secondary degeneration of cones, with photoreceptor rods appearing to be more affected than cones. Diseased photoreceptors face apoptosis,which results in reducing the thickness of the outer nuclear layer and the retinal pigment epithelium layer with abnormal pigmentary deposits. Although apoptosis and photoreceptor loss are common outcomes of all genetic types, their clinical features and progression are not homogeneous. It is currently known that while some photoreceptor cells do die, others appear to be in suspended animation . In the photoreceptor microenvironment,when growth factor (GF) levels or their receptor activities decrease over an extended period, apoptosis and cell death occur. The length of this period differs with each genetic type. The time during which there is a decrease in the effects of growth factors until cell death, the photoreceptors can be described as being in sleep mode, on standby, or in a dormant phase. In this phase, cone photoreceptors are alive, but they cannot function. GFs and neurotrophins, such as basic fibroblast growth factor (bFGF), neural growth factor (NGF), ciliary neurotrophic factor (CNTF), and brain-derived neurotrophic factor (BDNF), can significantly slow retinal degeneration and cell death in animal models. One possible source of autologous GFs is platelet-rich plasma (PRP). PRP is defined as a biological product that features platelet concentration; it is collected from centrifuged whole blood. Through the activation ofa reactivator (such as sodium chloride or citrate), accumulated platelets can secrete a large quantity of preparations rich in growth factors (PRGFs) via the release of intracellular α-granules. PRGFs are an aggregation of cytokines that include transforming growth factors (TGF-β), interleukine-6 (IL-6), BDNF, and vascular endothelial growth factors (VEGF). The strong restoring function of autologous PRP (aPRP) is based mainly on the trophic capacity of PRGFs . Currently, PRP is being tested as a therapeutic option in some clinical situations, for example in orthopedics, ophthalmology, and healing therapies. Some pre-clinical and clinical trials have addressed the use of PRP and various GFs, such as the intravitreal injection of bFGF in retinal dystrophy and the topical applications of NGF to treat glaucoma and neurotrophic keratitis. The use of PRGFs in ophthalmology has been successfully applied to ocular surface disorders, including the treatment of ocular surface syndrome and flap necrosis after LASIK surgery. A recent study observed that administration of platelet-derived proteins adjacent to the lacrimal gland restored lacrimal function in all patients. The clinical and pre-clinical use of aPRP in ophthalmology has encouraged practitioners to use it through subtenon injection in the treatment of retinal diseases. Through the subtenon injection of PRP, the level of neurotrophic growth factors may be increased in the microenvironment around the photoreceptors, thus potentially reactivating photoreceptors that are in sleep mode.Fetal bovine serum,allogeneic serum,and umbilical cord serum have also been used as sources of growth factors, but they are heterologous products with a higher risk of allergic reactions and infectious disease transmission. In order to avoid these issues, and because of the accessibility and relatively safe nature of aPRP, we chose to use aPRP as a source of growth factors in our study. The purpose of this prospective open-label clinical trial was to determine whether the subtenon injection of aPRP may have beneficial effects on visual functions-such as best corrected visual acuity (BCVA), visual field (VF), multifocal electroretinography (mfERG), and microperimetry (MP)-in RP patients with various degrees of narrowed visual fields.

• Study Type: Interventional
• Enrollment (Actual): 48
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Turkey
  • Türkiye
    • Ankara, Türkiye, Turkey, 06312
      • Ankara University Biotechnology Institute

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 55 years (Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

18 years of age or older;

• Diagnosis of any phenotypic variation of RP, confirmed by clinical history, fundus appearance, VF, and electroretinogram;
• Experience of various degrees of VF loss;
• BCVA from light perception of up to 110 letters (equal to 1.6 decimal values) in early treatment of diabetic retinopathy study (ETDRS) chart testing (Topcon CC-100 XP, Japan); & Mean deviation (MD) values from-33.0 to-5.0 dB with Humphrey or Octopus 900 visual field analysis (threshold 30-2, Sita Standard, Stimulus 3-white);
• Intraocular pressure (IOP) <22 mmHg.

Exclusion Criteria:

• The presence of cataracts or other media opacity that might affect the VF, MP, or mfERG recordings;

  • The presence of glaucoma, which causes visual field and optic disc changes;
  • The presence of any systemic disorder(e.g.,diabetes,neurological disease, or uncontrolled systemic hypertension) that may affect visual functions;
  • The habit of smoking.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Before application; Forty-nine eyes belonging to 37 patients before injection aPRP.	Biological: Platelet rich plasma; blood is drawn from the patient's antecubital vein and inserted into four 3.0 ml vacutainer tubes that contain trisodium citrate. These four tubes were placed in a centrifuge machine, and centrifugation was carried out at 2500 rpm (580×g) for 8 min within a 30-min blood collection period. As a result of centrifugation, the plasma was separated in the vacutainer tubes from the remaining blood components. Three different layers formed in the tubes: red blood cells at the bottom, aPRP in the middle layer, and aPPP in the top layer. A total of 1.5 ml of the middle layer (which mainly contained platelets) was withdrawn by syringe, and it was immediately injected into the subtenon space of each eye.
No Intervention: After application; Forty-nine eyes belonging to 37 patients after injection aPRP.
Sham Comparator: Sham application; 11 patients before - after aPPP injection	Biological: Platelet rich plasma; blood is drawn from the patient's antecubital vein and inserted into four 3.0 ml vacutainer tubes that contain trisodium citrate. These four tubes were placed in a centrifuge machine, and centrifugation was carried out at 2500 rpm (580×g) for 8 min within a 30-min blood collection period. As a result of centrifugation, the plasma was separated in the vacutainer tubes from the remaining blood components. Three different layers formed in the tubes: red blood cells at the bottom, aPRP in the middle layer, and aPPP in the top layer. A total of 1.5 ml of the middle layer (which mainly contained platelets) was withdrawn by syringe, and it was immediately injected into the subtenon space of each eye.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Visual field sensitivity	A Humphrey or Octopus 900 visual field analyzer, threshold 30-2 modality, was used at time points of 0,1,2,and 3.In addition, it was used three times before application during experimentation to exclude the learning effect. The MD values, which were obtained from the baseline test and the final examination, were analyzed and compared statistically to make conclusions regarding effectiveness. Visual field analysis could be properly performed on patients whose BCVA values were better than 50 letters in ETDRS chart testing (0.1 decimal)	Change from baseline visual field sensitivity at 1 month

Collaborators and Investigators

• Sponsor: Ankara Universitesi Teknokent
• Investigators: Principal Investigator: Umut Arslan, MD, Ankara Universitesi Teknokent

Publications and helpful links

General Publications

• Koenekoop RK. Why some photoreceptors die, while others remain dormant: lessons from RPE65 and LRAT associated retinal dystrophies. Ophthalmic Genet. 2011 Jun;32(2):126-8. doi: 10.3109/13816810.2010.544361. Epub 2011 Jan 26.
• Daftarian N, Kiani S, Zahabi A. Regenerative therapy for retinal disorders. J Ophthalmic Vis Res. 2010 Oct;5(4):250-64.
• Anitua E, Muruzabal F, Tayebba A, Riestra A, Perez VL, Merayo-Lloves J, Orive G. Autologous serum and plasma rich in growth factors in ophthalmology: preclinical and clinical studies. Acta Ophthalmol. 2015 Dec;93(8):e605-14. doi: 10.1111/aos.12710. Epub 2015 Apr 2.
• Arslan U, Ozmert E, Demirel S, Ornek F, Sermet F. Effects of subtenon-injected autologous platelet-rich plasma on visual functions in eyes with retinitis pigmentosa: preliminary clinical results. Graefes Arch Clin Exp Ophthalmol. 2018 May;256(5):893-908. doi: 10.1007/s00417-018-3953-5. Epub 2018 Mar 15.

Study record dates

Study Major Dates

• Study Start (Actual): September 1, 2016
• Primary Completion (Actual): February 28, 2017
• Study Completion (Actual): January 30, 2018

Study Registration Dates

• First Submitted: January 18, 2020
• First Submitted That Met QC Criteria: January 22, 2020
• First Posted (Actual): January 23, 2020

Study Record Updates

• Last Update Posted (Actual): January 23, 2020
• Last Update Submitted That Met QC Criteria: January 22, 2020
• Last Verified: January 1, 2020

More Information

Terms related to this study

• Keywords: Retinitis pigmentosa; Platelet rich plasma; Growth factors; Visual functions
• Additional Relevant MeSH Terms: Eye Diseases; Retinal Degeneration; Retinal Diseases; Genetic Diseases, Inborn; Eye Diseases, Hereditary; Retinal Dystrophies; Retinitis; Retinitis Pigmentosa
• Other Study ID Numbers: 12-596-16

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: No

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No