PuraGraft Hydrogel for Hemostasis and Tissue Repair

PuraStat is a synthetic, transparent hydrogel made from a self-assembling peptide called RADA16 that surgeons apply directly to bleeding tissue during and after procedures. Unlike traditional hemostatic agents that rely on animal-derived proteins or the body’s own clotting factors, PuraStat works mechanically by forming a nanoscale scaffold on contact with body fluids, physically sealing the wound surface. It has found its widest use in gastrointestinal endoscopy but is increasingly being applied in vascular, cardiac, sinus, and urological surgery, with a growing body of research exploring its potential as a tissue-regeneration platform.

How the Material Self-Assembles

RADA16 is a short synthetic peptide that exists as a clear, slightly acidic liquid inside its applicator. The moment it meets the neutral pH environment of blood or other body fluids, the peptide molecules spontaneously rearrange themselves into a three-dimensional mesh of nanofibers within seconds. The resulting hydrogel closely mimics the structure of the body’s own extracellular matrix, which is the microscopic scaffolding that normally surrounds and supports cells in living tissue.¹ This rapid transformation is what makes the product useful in surgery: it can be applied as a liquid through a catheter or syringe and then solidifies in place once it contacts the wet wound surface.

Because RADA16 is entirely synthetic, the manufacturing process avoids the biological variability and disease-transmission risks that come with animal- or human-derived hemostatic products like fibrin sealants or collagen-based agents. Its degradation products are ordinary amino acids, which the body can metabolize without triggering significant immune reactions.²

Stopping Bleeding Without the Clotting Cascade

Most traditional hemostatic agents work by accelerating some step in the body’s coagulation cascade, the chain reaction of clotting proteins that eventually produces a fibrin plug. That approach falls short in patients on blood thinners or those with clotting disorders, because the cascade is either chemically suppressed or biologically impaired. PuraStat sidesteps this problem entirely. The nanofiber hydrogel provides a physical barrier over the bleeding surface, tamponading the wound site regardless of the patient’s coagulation status.³ This is a meaningful clinical advantage, because a large proportion of patients undergoing gastrointestinal or vascular procedures are on anticoagulant or antiplatelet medications.

The gel is also fully transparent, which matters more than you might think. During endoscopy, the surgeon is working through a camera, and opaque hemostatic agents can obscure the visual field. A clear material allows the surgeon to keep watching the tissue underneath, assessing whether bleeding has stopped without having to remove anything.

Use in Gastrointestinal Endoscopy

The largest body of clinical evidence for PuraStat comes from gastrointestinal endoscopy, where it is applied to the raw tissue surface left behind after removing polyps, tumors, or other lesions. Delayed bleeding, meaning bleeding that starts hours or days after the procedure, is one of the most common complications of techniques like endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD). A large multicenter observational study of 448 patients who received prophylactic PuraStat on the resection base after advanced endoscopic resection found an overall delayed bleeding rate of just 1.34%.⁴ No delayed bleeds occurred in the esophagus, stomach, or left colon. The highest rate was in the duodenum, at about 9%, which is consistent with the duodenum being a notoriously difficult location for hemostasis regardless of the method used.

That said, the evidence is not uniformly positive. The PURPLE Trial, a multicenter randomized controlled trial comparing prophylactic PuraStat gel to standard care after EMR, found that delayed bleeding occurred in roughly 12% of the gel group compared to about 6% in the control group. That difference was not statistically significant, meaning the study could not confirm that the gel reduced delayed bleeding in that particular setting.⁵ The discrepancy between the observational data and this randomized trial highlights a recurring challenge in surgical hemostasis research: patient selection, lesion characteristics, and operator technique all influence outcomes in ways that can wash out the effect of any single product.

A separate prospective observational study specifically looking at active gastrointestinal bleeding reported no adverse events or technical failures related to PuraStat application, suggesting that the product is safe even if the magnitude of its benefit varies by context.⁶

Vascular and Cardiac Surgery

Bleeding at suture lines in vascular and cardiac surgery is a persistent problem. Even when a suture line looks secure, the needle holes themselves can ooze, and in patients on full anticoagulation (as is common during heart and artery operations), that oozing can be substantial. A multicenter study of PuraStat in elective carotid artery surgery reported hemostatic success in about 91% of applications, with a short time to bleeding cessation. The study also confirmed that the gel is safe for direct application on vascular anastomoses, the sewn-together junctions of blood vessels, without causing downstream complications like clotting or vessel narrowing.⁷

In cardiac surgery, a feasibility study found PuraStat effective across a range of procedures, including aortic operations, where the pressures and flow rates are among the highest in the body.⁸ These early-stage studies are small and lack randomized control groups, so they demonstrate safety and feasibility rather than definitive superiority over existing methods. But for surgeons, having an additional tool that works independently of the coagulation cascade is valuable, particularly in patients who cannot tolerate even brief interruptions in anticoagulation.

Sinus Surgery and Scar Prevention

Endoscopic sinus surgery creates raw tissue surfaces inside the nasal passages that are prone to two problems as they heal: bleeding and the formation of synechiae, which are bands of scar tissue that bridge across the nasal cavity and can block airflow or drainage. Traditional management involves packing the nose with sponge or gel materials, which can be uncomfortable and sometimes cause their own complications.

An animal study comparing RADA16 hydrogel to gelatin-thrombin (a conventional hemostatic packing material) and untreated controls found dramatic differences in synechiae formation. At two weeks, the RADA16 sites showed a 91% reduction in synechiae scores compared to untreated controls and a 92% reduction compared to gelatin-thrombin. Only 20% of RADA16-treated sites developed any synechiae at all, versus 75% of untreated wounds and 80% of gelatin-thrombin wounds. By six weeks, synechiae had resolved completely at every RADA16-treated site, while they persisted in half of the gelatin-thrombin sites and about a third of the controls.⁹ Tissue analysis showed that the gel reduced submucosal fibrosis, the abnormal scarring in the tissue layer beneath the mucous membrane, suggesting that the material actively promotes healthier healing rather than simply covering the wound.

These results are from a sheep model, not human patients, so they need to be interpreted with the usual caution about animal-to-human translation. Still, the magnitude of the difference is striking enough that human clinical trials in this space are underway.

Radiation Cystitis in Urology

One of the more compelling niche applications is the use of PuraStat for radiation cystitis, a condition in which the bladder lining becomes damaged and fragile after radiation therapy for pelvic cancers. Patients with severe radiation cystitis can experience persistent, heavy blood in the urine (hematuria) that is extremely difficult to manage. Standard treatments include bladder irrigation, cauterization, and hyperbaric oxygen, all of which have significant drawbacks and variable success rates.

An exploratory study of ten consecutive patients with persistent severe hematuria from radiation cystitis found that nine out of ten experienced complete resolution of visible blood in the urine after cystoscopic application of RADA16. The tenth patient had minimal, self-limiting episodes that had resolved by the one-year follow-up. No procedure-related adverse events were observed, and unplanned healthcare visits for the condition dropped to zero in all patients after treatment.¹⁰ For patients who have cycled through other options without success, a treatment that stops emergency room visits entirely is noteworthy, even in a study this small.

Beyond Bleeding Control and Into Tissue Regeneration

Because the RADA16 nanofiber scaffold mimics the extracellular matrix, researchers have been investigating whether it can do more than just stop bleeding. The idea is that the same mesh that physically blocks blood flow might also serve as a temporary scaffolding for cells to grow into, promoting tissue repair from the inside out.

Laboratory and animal studies have explored injectable versions of self-assembling peptide hydrogels for chronic wound healing. In one study, a peptide hydrogel injected into chronic wounds stayed in place for up to seven days and accelerated wound closure by roughly 20% compared to control groups. The treated wounds also showed increased formation of new blood vessels, greater cell proliferation, and better collagen deposition, all hallmarks of healthy tissue repair.¹¹ That particular study used a related peptide formulation rather than the exact RADA16 product sold as PuraStat, but the underlying self-assembling mechanism is the same family of technology.

The broader field of supramolecular peptide nanofiber hydrogels is also being explored for bone tissue engineering, where the ability to tune the mechanical properties and functionalize the peptide surface with growth-promoting molecules could make these materials useful as bone graft substitutes or delivery vehicles for bone-stimulating factors. This work is still largely preclinical, but it illustrates how versatile the platform is. The same basic chemistry that stops a bleed during endoscopy might eventually regenerate bone or skin, depending on how the peptide is modified.

Safety Profile and Practical Handling

Across the published studies, the safety signal for PuraStat has been consistently clean. The multicenter observational pilot study in gastrointestinal bleeding reported zero adverse events related to the product and zero technical failures during application.¹² The carotid artery surgery study similarly found no safety concerns at the vascular anastomosis sites.¹³ The radiation cystitis study recorded no procedure-related adverse events across its cohort.

Part of this favorable safety profile comes from the material’s composition. Since RADA16 is a short synthetic peptide that degrades into standard amino acids, there is no risk of transmitting infectious agents (a theoretical concern with bovine- or porcine-derived products) and minimal risk of allergic or immune reactions. The gel is also absorbed by the body over time, so there is nothing permanent left behind that might cause long-term foreign body reactions.

From a practical standpoint, the product comes in a prefilled syringe and can be delivered through standard endoscopic channels or applied directly during open surgery. Surgeons who have used it note that the transparency is a genuine workflow advantage, particularly during endoscopy, because it avoids the visual obstruction caused by opaque powder-based or foam-based hemostats.

How It Compares to Conventional Options

Traditional surgical hemostats fall into a few broad categories: topical agents like oxidized cellulose or gelatin sponges that provide a physical matrix for clot formation; biologically active sealants like fibrin glue or thrombin-based products that directly trigger the coagulation cascade; and mechanical devices like clips or cautery. Each has trade-offs. Fibrin sealants are effective but expensive and carry residual biological risk. Oxidized cellulose can swell and compress nearby structures. Cautery works but damages surrounding tissue. Clips are secure but cannot cover diffuse oozing over a broad surface.

PuraStat occupies a different niche. It excels at controlling diffuse, low-to-moderate oozing over a wide area, precisely the kind of bleeding that clips cannot catch and cautery would overtreat. Its independence from the coagulation cascade makes it useful in anticoagulated patients where biologically active sealants may underperform. Its transparency gives it an edge during endoscopic procedures. And its synthetic origin avoids the supply-chain and biosafety concerns of animal-derived products.

Where PuraStat is less suited is in managing high-pressure arterial bleeding, where the mechanical force of blood flow can wash away the gel before it fully sets. It is also not a replacement for sutures or clips in situations where a vessel needs to be mechanically closed. It is best understood as a complement to existing tools rather than a replacement for all of them. A narrative review on managing bleeding in oral surgery placed PuraStat among “novel local bleeding control products” that are proving useful in high-risk surgical settings by promoting rapid hemostasis without adverse effects.¹⁴

Where the Evidence Still Has Gaps

The honest assessment is that most PuraStat evidence comes from observational studies, feasibility trials, and single-arm cohorts. The one large randomized controlled trial in endoscopy, the PURPLE Trial, did not find a statistically significant benefit over standard care for preventing delayed bleeding after EMR.¹⁵ That does not mean the product is ineffective; it may mean the benefit is smaller than observational studies suggested, or that EMR after standard polyp removal is not the ideal use case. The observational data on high-risk resections, particularly in the duodenum and right colon, look more promising, which fits the intuition that the product’s value increases as bleeding risk increases.

Head-to-head trials against specific competitor products are also scarce. Much of the comparative reasoning comes from animal models or from indirect comparisons across different studies with different patient populations. The sinus surgery data, while impressively one-sided, comes from a sheep model and awaits human replication. The radiation cystitis data, while clinically meaningful, comes from just ten patients at two centers. These are common growing pains for a relatively new surgical product, but they mean that clinicians adopting PuraStat are relying partly on mechanistic plausibility and favorable safety signals rather than the kind of large-scale comparative evidence that exists for older hemostatic agents.

Cost is another open question. Self-assembling peptide hydrogels are more expensive per unit than basic hemostatic products like oxidized cellulose or gelatin sponges. Whether the clinical benefits, particularly the potential reduction in emergency readmissions for delayed bleeding, offset the higher per-procedure cost is something health economists are still working through. The radiation cystitis study’s finding that unplanned healthcare visits dropped to zero hints at downstream savings, but formal cost-effectiveness analyses across the product’s range of applications are still needed.