by Susan Hsiong, PhD

More than 12 million minimally invasive vascular surgeries are done every year. These procedures require catheterization of major blood vessels to gain access to the vasculature. While catheter technology has dramatically improved, closure of the vessel puncture wound post surgery remaines a challenge. Manual compression of the puncture site is the traditional method used to stop bleeding, but this often requires hours and renders the patient immobile. Rapid closure of the puncture site is critical to stop bleeding and to get the patient out of the hospital and back to normal activity.

About ten years ago, biomaterial-based vascular closure devices were introduced, such as St. Jude Medical’s Angio-Seal or Datascope Inc.’s VasoSeal. These first generation devices were essentially collagen based products that were used to “plug” the vessel puncture site (see an animation of the Angio-Seal device placement here). While this first generation of products addressed the initial need and helped establish the market, complications such as infections or hematoma often occurred. It is unclear if the complications are due to the collagen biomaterials, or the method of delivering the materials to “plug” the puncture wound. For these reasons, adoption of this technology has been limited.

With the vascular closure market currently estimated at over $2 billion, innovative products are being designed to address the limitations of previous vascular closure devices. Two companies focusing on this space are AccessClosure (Mountain View, CA) and NeoMend Inc (Irvine, CA). The second generation devices include use of synthetic materials (e.g. PEG) and new deployment methods which minimize complications and improve vessel healing. These synthetic materials yield more consistent results, perhaps due to a more consistent product and product processing than is available for naturally derived collagens. Also, the new devices are delivered extravascularly (outside the blood vessel wall), avoiding complications triggered by penetrating the intravascular space (occlusions, embolisms, etc.). An additional advantage of these new devices is that they are degradable, nothing is left but a healed vessel.

AccessClosure (Mountain View, CA) received FDA approval last December for its Mynx™ product, a vascular sealant comprised of a water soluble, degradable hydrogel (PEG polymer). The device is deployed extravascularly to the ateriotomy (puncture site) where upon contact with blood and other fluids, the polymer swells to 3-4x its original size, thus closing the puncture and promoting hemostasis (see product animation here). The polymer sealant then dissolves within 30 days.

NeoMend (Irvine, CA) has developed ProGEL™ technology, a Pro/PEG hydrogel biomaterial combining a component of human serum albumin cross-linked with PEG to create a very strong, yet degradable, sealant. ProGEL™-VS (their vascular closure product formulation) has successfully completed a pilot clinical study and has an approved IDE for its pivotal US study. NeoMend has formulated its ProGel™ technology for a variety of other applications outside vascular closure: ProGEL-AB prevents post-surgical adhesions (the most common complication of surgery) and ProGEL™ is a surgical sealant used for intraoperative air leaks.

Although the Mynx™ and ProGEL™ are both PEG based devices, there are some important differences in the strategy the companies are taking with them:

• Applications: The Mynx™ is primarily focused on endovascular procedures. ProGel™ is being directed for broader use, and can be used in open surgery or laproscopic procedures. In addition to acting as a sealant, ProGel™ can also act a barrier to prevent post-surgical adhesions.
• Delivery method: the Mynx™ is deployed via a specialized procedural sheath whereas ProGEL™ can be delivered more simply: sprayed onto surgical site or injected via a catheter or syringe.
• Market: NeoMend is targeting a wider market segment as their platform technology is more flexible to different applications. It would be interesting to see how this strategy plays out as compared to the more focused strategy of AccessClosure.
  

It remains to been seen how much market penetration will be achieved with new vascular closure products such as the Mynx™ and ProGEL™. If the devices demonstrate consistent vascular closure with minimal complications, and are easy for the surgeons to use, then these next generation biomaterial-based products will gain more ground in the surgery room and expand the endovascular market. However, it is likely that the St Jude and Datascope will defend their markets with new products of their own, potentially with better delivery methods. The eventual winners may be the products that most simply closes the puncture site as well as best address the surgeons’ needs.