Stem Cell Therapy vs Conventional Treatment for Retinitis Pigmentosa

Conventional care for retinitis pigmentosa (RP) can slow or manage vision loss, and one gene therapy can restore useful vision in the small group with RPE65 mutations. Stem cell therapy for RP is still investigational: early trials suggest it can be done safely, but no large controlled trial has yet proven that it restores or preserves vision. The most responsible approach is to use proven care first, and consider stem cell therapy as a supervised, evidence-aware addition rather than a cure.

• RP is a group of inherited diseases in which the light-sensing cells of the retina gradually die, starting with night vision and the side (peripheral) field.
• Conventional options include genetic testing, vitamin A palmitate for some adults, treatment of cataract and macular swelling, low-vision rehabilitation, and, for RPE65-related disease only, the gene therapy voretigene neparvovec (Luxturna).
• A gene-agnostic optogenetic therapy, MCO-010 (Mogenry), has had its application accepted by the US FDA but is not yet approved.
• Stem cell therapy trials for RP (mesenchymal, CD34+ and others) are mostly small phase 1 or 2 studies. They report acceptable safety, with mixed and unproven benefit.
• No treatment, conventional or stem-cell-based, is a proven cure for RP.

Retinitis pigmentosa is a group of inherited retinal diseases in which the rod and cone cells that detect light slowly degenerate, causing progressive vision loss. It is caused by changes in any of more than 100 genes, which is why it varies so much between families and why one treatment cannot fit every patient (Ophthalmology stem cell trial review, 2025). It can be passed on in an autosomal recessive, autosomal dominant or, less often, X-linked pattern, and it can be part of a syndrome such as Usher syndrome, which also causes hearing loss (MSD Manual).

• Poor night vision, often the first sign, sometimes beginning in childhood.
• Shrinking side vision (tunnel vision), as a ring-shaped blind area widens from the periphery inward.
• Reduced central vision in later stages, which can progress to legal blindness.
• Associated problems: posterior subcapsular cataract, swelling at the macula (cystoid macular edema) and nearsightedness.

An eye specialist usually diagnoses RP from a dilated retinal exam, which shows the typical dark “bone-spicule” pigment, supported by an electroretinogram (ERG) that measures how well the retina responds to light (MSD Manual). Genetic testing is increasingly important because it decides whether a gene-specific therapy is possible, and it guides family counselling.

For more background, see Viezec’s guides on rod and cone dystrophy and stem cells for inherited retinal disorders.

Conventional RP treatment aims to slow progression, treat complications and keep a patient functional; only RPE65-related RP has an approved therapy that improves vision. Standard care today is a combination of the options below.

Possibly, but it is not approved yet. Nanoscope Therapeutics’ MCO-010 (sonpiretigene isteparvovec, “Mogenry”) is a one-time optogenetic therapy injected into the vitreous that makes surviving retinal cells light-sensitive, whatever the underlying gene. Its pivotal sham-controlled trial met its primary endpoint, and the US FDA has accepted its application with a decision expected in the first half of 2027 (Retinal Physician). Until it is approved and available, it remains investigational.

None of these options can regrow lost photoreceptors in a patient without an RPE65 mutation. That gap is the reason researchers are studying cell-based approaches, including stem cells.

Stem cell therapy for RP does not yet replace lost photoreceptors in routine practice; the leading idea is that injected cells release protective growth factors that support the surviving retinal cells and slow their decline. This “paracrine” effect is the main proposed mechanism for mesenchymal stem cells (MSCs), and it is why most current trials aim to preserve or modestly improve function rather than rebuild the retina. Replacing photoreceptors with lab-grown cells is a separate and earlier research field.

• Mesenchymal stem cells (MSCs) from bone marrow, umbilical cord or fat. This is the most common cell type in eye trials, used in 43 of 88 ophthalmology stem cell trials reviewed in 2025 (PMC review). See Viezec’s explainer on how mesenchymal stem cells work.
• CD34+ cells collected from the patient’s own bone marrow and injected into the eye. A phase 1 trial reported on seven RP patients (UC Davis Health, 2024).
• Stem cell-derived extracellular vesicles (exosomes), tiny packets of signals released by cells. A safety and efficacy trial in RP is registered (ClinicalTrials.gov NCT06242379); see also Viezec’s page on exosome therapy for retinitis pigmentosa.
• Embryonic or iPSC-derived retinal cells, which aim to replace lost cells. These are mainly in laboratory and early clinical research.

The main routes are intravitreal (into the gel of the eye), subretinal (under the retina, by surgery), suprachoroidal (a layer behind the retina) and systemic (intravenous). A 2025 meta-analysis of 11 studies and 355 RP patients found that subretinal and suprachoroidal delivery were associated with better outcomes than systemic infusion (Int Ophthalmol, 2025). Each route has different surgical risks, which is why the route should be explained to you before consent.

To see how Viezec approaches eye conditions, read stem cell treatment for retinitis pigmentosa and how effective stem cell therapy is for retinitis pigmentosa.

The main difference is evidence: conventional care and gene therapy are regulated and tested in controlled trials, while stem cell therapy for RP is still investigational.

Sources for this table: MSD Manual, Healio, meta-analysis and phase I trial.

The evidence shows that carefully delivered cell therapy can be tolerated by most RP patients, but it does not yet prove lasting visual benefit. Here is what the main studies found.

• Meta-analysis, 2025: 11 studies and 355 RP patients treated with umbilical cord or bone marrow MSCs. Short-term gains in visual acuity were reported, adverse events were minimal (mainly transient inflammation), most benefits lasted up to 12 months, and the authors called for larger randomized trials (Int Ophthalmol).
• CD34+ phase 1 trial, 2024: seven patients received a single injection of their own bone marrow CD34+ cells into one eye. It was well tolerated, and four of seven showed measurable improvement, but the study was designed to test safety, not efficacy (UC Davis Health).
• Intravitreal MSC phase I trial, Thailand: 14 adults with advanced RP. Acuity rose slightly at some time points but returned to baseline by 12 months. Eye pressure rose briefly, and inflammation settled within about 14 days. One participant developed a vitreous hemorrhage around year 3 that needed surgery (PMC).
• Field status, 2025: RP is the second most-studied eye disease in stem cell trials after macular degeneration, yet most trials are phase 1 or 2 (PMC review).

In controlled early-phase trials, serious complications were uncommon. Outside regulated trials, the risk is real. In 2017, three women with macular degeneration were left blind after receiving fat-derived stem cells in both eyes at a for-profit US clinic, with detached retinas, bleeding and vision loss reported (Live Science, citing the NEJM report). The lesson is not that cell research is unsafe, but that the clinic, the cell product, the route and treating one eye at a time matter.

• No guaranteed cure or guaranteed vision gain.
• Clear explanation that the therapy is investigational, with written informed consent.
• A named ophthalmologist who examines your eyes before and after treatment.
• Quality-controlled, documented cells (quality control tests).
• Honest discussion of risks (safety and adverse effects, stem cell therapy safety).

For results documented at Viezec, see the clinical outcome page and stem cell clinical trial results.

Stem cell therapy for RP is generally considered an add-on to conventional care, not a replacement for it. Whether it suits you depends on your eye findings, your genetics and how you weigh uncertain benefit against risk; this decision belongs with a retina specialist.

1. Do you have a confirmed RP diagnosis? Get a dilated exam, ERG and, if possible, genetic testing from a retina specialist.
2. Do you carry biallelic RPE65 mutations? If so, ask first about voretigene (Luxturna), the approved option.
3. How advanced is your vision loss? The authors of the Thailand phase I trial recommended testing in less advanced disease, with longer follow-up (PMC). Ask what outcomes are realistic at your stage.
4. Are there other eye problems to treat first? Active infection, inflammation or poorly controlled eye pressure would normally need to be resolved first; your ophthalmologist decides.
5. Are your baseline tests recorded? Visual acuity, visual field, ERG and retinal imaging taken before treatment are the only way to judge any change afterwards.

Yes, in most cases. Keep your regular eye follow-up, any prescribed supplements, cataract or macular edema care and low-vision support. Tell every treating doctor about all treatments you are using, and do not stop prescribed medicine without advice. Nutrition also matters for retinal health; Viezec shares diet tips for retinitis pigmentosa patients.

• Ask whether the treatment is part of a registered trial, and check ClinicalTrials.gov.
• Ask which cells, how they are collected and tested, and which route is used.
• Ask for the written risk list, including what happens if something goes wrong.
• Ask who will examine your eyes and how you will be followed up.
• Be cautious if the clinic promises a cure, treats both eyes on the same day, or cannot show its quality controls.

If you are travelling from abroad, read Viezec’s international patient flow chart and medical visa process. To discuss your reports, contact the Viezec team for an evaluation before making any decision.