Islet transplantation into the anterior chamber of the eye
What this study tests
A two-person safety study putting donor islets into the front chamber of a blind eye — a site chosen because the graft can be watched through a microscope, and because the eye may tolerate a transplant with less drug cover. It is often described as "immunosuppression-free". It is not. Every recipient gets a short course of systemic induction immunosuppression around the transplant, then ongoing maintenance immunosuppression as eye-drops (topical steroids plus ciclosporin or tacrolimus). Recipients who already have a kidney transplant stay on their chronic systemic anti-rejection drugs throughout. What is genuinely being tested is whether *maintenance* immunosuppression can be local rather than systemic — a real question, but a narrower one than "no drugs".
Editorial review: .
Registry checked: 2026-09-17. Registry’s own update: 2026-03-12.
Most recent recorded citation date: 2019-03-06. Only explicit date metadata is included; an undated citation may be newer. This does not mean every claim was reviewed on that date.
Trial status, labels and access can change between reviews. How we review the evidence · How to read the evidence
Evidence at a glance
- Who can enter the study?
- Adults 18-75 with type 1 or type 2 diabetes who have at least one eye with extensive loss of vision — hand-motion to no-light-perception — and otherwise normal anterior-segment anatomy in that eye. Kidney function must be stable (native or transplanted); a prior kidney transplant is allowed but not required. Excluded for glaucoma, active uveitis, corneal opacity, HbA1c above 10%, significant anti-HLA sensitisation, active infection or malignancy. See the registry for the full criteria. Registered eligibility ↗Enrollment criteria describe who may enter. They do not establish who was analyzed or the denominator for a reported result.
- Reported benefit and results
- No results posted. Note what this trial is and is not designed to show. Target enrolment is 2 participants; it opened in December 2019 and is still recruiting, with primary completion estimated December 2026. All three primary endpoints are about ocular safety and whether the graft survives *in the eye* — none is about insulin independence, HbA1c, or time in range. So even a completely successful result here would be evidence that islets can live in the eye under local drug cover, in a couple of people, with a graft too small and a site too novel to be a treatment. It would not be evidence of a cure, and it would not be evidence of a drug-free transplant. The supporting preclinical work is honest about the ceiling: in mice, releasing rapamycin locally in the anterior chamber *delayed* islet rejection rather than preventing it.Read the result sources and their limitations →
- Important harms
- Read the reported results, safety discussion and original sources. A separate harms summary is not available; this does not establish safety.
- Research access and approval
- Study regions: United States. A trial listing does not establish product approval or current recruitment at a particular site. Check the study’s current entry requirements.
- What remains uncertain?
- Read the full discussion and original sources for study limitations. Planned endpoints and completion dates are not results.
Research status alone does not establish approval, clinical benefit or local availability. This record cites company or conference reports. Those sources may describe interim findings; their source type is shown in the source list.
Primary endpoints
- Absence of ocular complications in the transplanted eye at 24 months
- Absence of sympathetic ophthalmia (immune damage to the *other*, untreated eye) at 24 months
- Confirmation of intraocular islet graft survival — C-peptide above 1 ng/ml in the aqueous humour of the transplanted eye, plus imaging of graft integrity
The full picture
What is being tested
Donor islets are infused into the anterior chamber of the eye — the fluid-filled space between the cornea and the iris — instead of the liver, where clinical islet transplants normally go.1 The islets settle on the iris, where they take up a blood supply and can be looked at directly through a slit lamp, month after month, in a living person. That is the main attraction: unlike other transplant sites, the graft can be watched directly.1
The second attraction, and the reason this record needed correcting, is immunological. The eye is an immune-privileged site, and the hope is that a graft there can be held with local drug cover rather than the systemic anti-rejection drugs that make conventional islet transplant a bad trade for most people.12
This is not an immunosuppression-free approach
Say it plainly, because the framing in the field drifts:
- Every participant receives systemic induction immunosuppression — a short course of drugs in the days around the transplant.2
- Maintenance immunosuppression is not absent; it is topical. It is given as eye-drops — planned for two years after the transplant — and the registry's exclusion criteria name topical steroids plus a calcineurin inhibitor (ciclosporin or tacrolimus) as the agents involved.12 Local is not none. It is a different route, and it carries its own risk of local toxicity and of failing to control an attack that is happening systemically.
- Participants who already have a kidney transplant stay on chronic systemic immunosuppression for that kidney, on their transplant team's instructions, for as long as the kidney lasts.2 For those participants the eye graft is protected by drugs they were already taking. It is not a demonstration that a drug-free islet graft is possible.
- Nothing here touches the autoimmunity. The topical drugs are anti-rejection cover for a foreign graft. The immune memory that destroyed the person's own beta cells in the first place is untreated.
The genuine, narrower claim the trial is testing: that for a recipient without another organ transplant, maintenance immunosuppression could be delivered locally to the eye instead of systemically — reducing, not eliminating, lifetime drug exposure.2 That would be worth having. It is not the same claim as "no immunosuppression", and the only human on record with transplanted insulin-producing cells surviving on zero immunosuppressive drugs remains the single Sana UP421 participant (a company-reported case, not verified against a primary source in this review).
How far along it is
Very early. It is a Phase 1/2 safety study with a target enrolment of two people, open since December 2019 at the Diabetes Research Institute and the Bascom Palmer Eye Institute in Miami, still recruiting as of July 2026.1 Eligibility requires an eye that is already effectively blind — hand-motion vision down to no light perception — which is the ethical premise of the whole design: you do not put an experimental graft in an eye that still sees.1
The three primary endpoints are ocular safety (no corneal decompensation, raised pressure, uveitis, endophthalmitis), absence of sympathetic ophthalmia in the other eye, and confirmation that the graft is alive — C-peptide above 1 ng/ml in the aqueous humour of the treated eye.1 Note what is missing from that list: HbA1c, time in range, insulin dose, insulin independence. This trial is not designed to make anyone's diabetes better, and its results cannot show that it did.
The realistic ceiling
The preclinical literature supports the site, and is candid about the drug question. In mice, islets survive and function in the anterior chamber, and the site allows imaging not possible elsewhere.3 But when researchers tried delivering the immunosuppressant locally in the eye — rapamycin released from microparticles alongside the islets — the grafts survived longer than controls and were still rejected.3 Delay, not prevention, in mice.
So the honest read of this trial: it is a monitoring and site-feasibility study, valuable mainly because it lets us watch a human islet graft live and learn how it is attacked. Treat any framing of it as a step toward a drug-free cure with suspicion.
Sources
- [1]NCT02846571 — Pancreatic Islet Transplantation Into the Anterior Chamber of the Eye · Trial registry — Retrieved 15 July 2026. Phase 1/2, interventional, enrolment 2, recruiting; started 5 December 2019, primary completion estimated 31 December 2026. The brief summary states recipients "will receive localized maintenance immunosuppression via topical application of eye-drops"; the ophthalmic exclusion criteria name topical steroids, ciclosporin and tacrolimus.
ClinicalTrials.gov. Pancreatic Islet Transplantation Into the Anterior Chamber of the Eye (NCT02846571). Retrieved 15 July 2026.
- [2]Intraocular Islet Transplant · Manufacturer — The sponsoring institution's own description of the trial. Source for the systemic induction course given around the transplant, and for the fact that participants with a kidney transplant continue their chronic systemic maintenance immunosuppression as directed by their transplant physician.
Diabetes Research Institute Foundation. Intraocular Islet Transplant.
- [3]Local release of rapamycin by microparticles delays islet rejection within the anterior chamber of the eye · Peer-reviewed study · 2019-03-06 — Mouse study. Local drug delivery in the anterior chamber prolonged islet survival (past day 30 versus rejection by day 18 with blank microparticles) but did not prevent rejection.
Fan Y, Zheng X, Ali Y, Berggren P-O, Loo SCJ. Local release of rapamycin by microparticles delays islet rejection within the anterior chamber of the eye. Scientific Reports (2019);9:3918.