Medical devices & diagnostics · Dialysis vascular access
VenoStent
A bioabsorbable polymer sleeve that a surgeon slips over a newly built dialysis fistula and leaves behind to dissolve. It has an FDA Breakthrough Device designation and a randomized trial still enrolling. It has no FDA clearance, no approval, and no published clinical paper.
Five extra minutes
A vascular surgeon opens a forearm, finds an artery and a nearby vein, and sews them together. The vein was built to carry blood back to the heart at low pressure. It now carries arterial blood. VenoStent puts the jump at roughly tenfold in pressure and flow.
About half the time the vein does not cope. Cells in the wall migrate inward instead of out, the channel narrows, clots form, and the fistula never carries a dialysis needle. The patient keeps a catheter in the chest, and catheters bring infections.
VenoStent’s answer is a sleeve. SelfWrap is a printed, macroporous polymer that softens near body temperature, so a surgeon can mold it onto the join by hand. It holds the vein in an artery-like shape while the vein adapts, then breaks down and is replaced by the patient’s own tissue. Norwest Venture Partners, an investor, wrote that placing it adds 5 to 10 minutes to the operation.
No second incision. No permanent implant. That is the whole pitch.
A surgery that fails about half the time
The arteriovenous fistula is the best dialysis access anyone has. It outlasts a synthetic graft and kills fewer people than a catheter. It also fails constantly, and has for sixty years.
The company’s NIH grant abstract states the case in plain numbers: 39 percent of the fistulas created in the United States are never used for dialysis, 50 percent are abandoned within twelve months, and one year and five year hemodialysis mortality run at 21 percent and 60 percent. Nothing on the market fixes this. That is the unusual feature of the field. The failure rate is not in dispute, the cost is not in dispute, and the shelf is empty.
A polymer, and a reason to use it
Timothy Boire found the material first. A chemical engineer from Tufts, he spent three years at Genzyme, then went to Vanderbilt for a PhD, and in 2012 found a shape memory polymer he could tune to soften near body temperature. In 2014 he joined the National Science Foundation’s I-Corps program and spent it interviewing vascular surgeons, nephrologists and dialysis patients. He went in thinking about bypass grafts and came out thinking about dialysis access. His 2017 dissertation followed.
Geoffrey Lucks was finishing an MBA at Vanderbilt when the two were introduced. His pull toward medicine was personal: his brother lived with spina bifida and died in 2008.
TechCrunch found them close to broke in 2020, having left Nashville for Texas and their first accelerator, with Boire describing nearly three sleepless nights inside the Johnson & Johnson JLABS site in Houston synthesizing polymer and printing sleeves. By then they had a KidneyX prize from HHS and the American Society of Nephrology, federal grant money, and a place in Y Combinator’s Summer 2020 batch.
Denied, then designated
The first application for Breakthrough Device status went in during 2019 and the FDA turned it down. The founders later described taking the critique apart point by point, booking pre-submission meetings, and assembling a scientific advisory board before going back.
In between came the human data. A single arm feasibility study opened in Asunción, Paraguay in June 2021 and enrolled twenty patients; enrollment closed that October. The designation arrived in May 2022, an investigational device exemption in May 2023, and a $16 million Series A the same month the exemption was announced.
The first US patient was randomized on February 1, 2024, at Surgical Specialists of Charlotte. The registry listed 28 recruiting sites at its last update in February 2026, among them Houston Methodist, Mayo Clinic, Brigham and Women’s Hospital and Northwell Health.
What is proven, and what is still claimed
| Evidence | What the record shows | Source type |
|---|---|---|
| FDA clearance or approval | None. The 510(k) and PMA databases return no VenoStent entries as of September 22, 2026. The company’s own site reads “Investigational Device. Limited by Federal Law to Investigational Use.” | Public record |
| Breakthrough designation | Announced May 2022, reported by Medical Product Outsourcing and Renal Interventions. The FDA publishes no device level list of these, so it rests on the company plus trade reporting. It is not a clearance and permits no sale. | Company-stated |
| Investigational device exemption | Granted May 2023 per the company, reported consistently by MassDevice, InnovationMap and Renal Interventions. IDE decisions are not published either. An IDE authorizes a trial, not a market. | Company-stated |
| Feasibility study | NCT05418816. Single center, single arm, 20 patients enrolled, one site in Asunción, Paraguay. Started June 14, 2021, primary completion February 23, 2022. Active, not recruiting. | Public record |
| Feasibility results | Presented at the VEITHsymposium in November 2024 by Ellen Dillavou of WakeMed: 95 percent functional and 90 percent unassisted maturation against benchmarks of under 58 and 33 percent, and no adverse events probably or definitely device related through 36 months. | Conference report |
| Peer-reviewed publication | None found. PubMed searches for SelfWrap, VenoStent and bioabsorbable perivascular wraps in fistulas return nothing from the company as of September 22, 2026. | Not found |
| Pivotal trial as registered | NCT06001827. Randomized 1:1, participant and assessor masked, 600 estimated enrollment, 28 sites recruiting, start January 3, 2024, primary completion estimated June 2027, study completion estimated December 2029. | Public record |
| Trial size, announced against registered | Releases in 2024, MassDevice, InnovationMap and Houston Methodist all describe a 200 patient trial. The registry says 600, and the company’s own provider page says “approximately 600 participants from up to 30 investigational sites.” The number tripled without an announcement. | Differs from registry |
| Approval timing | Norwest’s investment note said the company “expects to receive FDA approval for SelfWrap in late 2026.” The trial is still recruiting and primary completion is estimated for June 2027. | Overtaken |
| Federal funding | NIH NHLBI, eight awards FY2020 to FY2026 totaling $5,908,445, including three worth $1,921,359 that began in September 2026. NSF STTR Phase I $224,482 and SBIR Phase II $1,294,224. Combined: $7,427,151. | Public record |
Read plainly: the science has cleared the bars that come before proof and none of the bars that count as proof. Twenty unrandomized patients in one hospital produced numbers that look extraordinary against historical benchmarks, which is what a randomized trial exists to test. That trial is running, it has tripled in size since it was announced, and its first real answer is not due until the middle of 2027.
What to watch
- Whether enrollment reaches 600 and the June 2027 primary completion date holds. It has already outlived the approval date an investor note projected.
- A peer-reviewed paper on the feasibility data. Conference slides are the weakest form in which a 90 percent maturation figure can travel.
- A premarket approval submission. The founders have said they chose the Class III route for its pricing and reimbursement upside.
- What the $10 million of convertible notes sold in April 2026 paid for. No release accompanied the filing.
- The three NIH awards that started in September 2026, two of them for manufacturing scale up and long term degradation testing.
In their words
“This is a major step towards helping chronic kidney disease patients in the United States. We are grateful to the team at FDA, our own team, and all of those who have backed us over the years.”
Tim Boire, co-founder and CEO, on the Breakthrough designation, Medical Product Outsourcing, 2022 · Company release
“While it’s ambitious and sets a high bar for FDA approval, we owe it to the chronic kidney disease (CKD) patient community to provide the highest level of clinical evidence.”
Tim Boire, on launching the randomized trial, Renal Interventions, 2024 · Company release
“I’m thrilled that the company has progressed to this stage. I applaud them for doing an RCT with level A clinical evidence in mind, as this will be essential to convince physicians of its utility if and when it attains FDA approval.”
Eric Peden, chief of vascular surgery, Houston Methodist, trial principal investigator, Renal Interventions, 2024 · Investigator
“If we can reduce the failure rate from 60 percent to 30 percent, that would be a major step forward for patients.”
Eric Peden, Houston Methodist, 2025 · Investigator
“Since the first fistula creation surgeries of the 1960s, there have been drugs, devices and new approaches attempting to reduce AVF failure rates, but none have ever definitively been proven to do so.”
Eric Peden, Houston Methodist, 2025 · Investigator
“these results would be very impactful for chronic kidney disease/ESRD patients requiring haemodialysis”
Ellen Dillavou, WakeMed Heart Center, on the feasibility data, VEITHsymposium, reported by Renal Interventions, 2024 · Conference
“transparency with FDA is essential.”
Tim Boire, on returning after a rejected designation application, Medsider interview · Interview
“Investors invest in lines, not dots.”
Geoffrey Lucks, co-founder and COO, Medsider interview · Interview
Related companies
Sources
- Public recordClinicalTrials.gov NCT06001827 and NCT05418816
- Public recordNIH RePORTER, eight NHLBI awards to VenoStent
- Public recordNSF awards 1819996 and 1927086
- Public recordFDA 510(k) and PMA databases
- Public recordPubMed, no VenoStent or SelfWrap publications
- Public recordForm D filings, CIK 0001734734
- Public recordKidneyX Redesign Dialysis Phase 2 prize winner page
- IndependentVenoStent’s SelfWrap Earns Breakthrough Status
- IndependentFirst subjects enrolled in US clinical trial for VenoStent
- IndependentNovel bioabsorbable perivascular wrap aims to reduce AVF failure
- IndependentHouston Methodist Leads the Way in Groundbreaking Arteriovenous Fistulas Trial
- IndependentVenoStent has a new technology to improve outcomes for dialysis patients
- InterviewProof Before Funding: Tim Boire and Geoffrey Lucks
- CompanySeries A and IDE releases, 2023 and 2024
- CompanyVenoStent website and the SAVE-FistulaS trial site
- InvestorVenoStent: The Promise of Safer Treatment for Dialysis Patients
Profile researched and written by Healthcare Discovery. Last updated September 29, 2026.
