Biomaterials in Gastroenterology: A Critical Overview

Abstract

In spite of the large diversity of diagnostic and interventional devices associated with gastrointestinal endoscopic procedures, there is little information on the impact of the biomaterials (metals, polymers) contained in these devices upon body tissues and, indirectly, upon the treatment outcomes. Other biomaterials for gastroenterology, such as adhesives and certain hemostatic agents, have been investigated to a greater extent, but the information is fragmentary. Much of this situation is due to the paucity of details disclosed by the manufacturers of the devices. Moreover, for most of the applications in the gastrointestinal (GI) tract, there are no studies available on the biocompatibility of the device materials when in intimate contact with mucosae and other components of the GI tract. We have summarized the current situation with a focus on aspects of biomaterials and biocompatibility related to the device materials and other agents, with an emphasis on the GI endoscopic procedures. Procedures and devices used for the control of bleeding, for polypectomy, in bariatrics, and for stenting are discussed, particularly dwelling upon the biomaterial-related features of each application. There are indications that research is progressing steadily in this field, and the establishment of the subdiscipline of “gastroenterologic biomaterials” is not merely a remote projection. Upon the completion of this article, the gastroenterologist should be able to understand the nature of biomaterials and to achieve a suitable and beneficial perception of their significance in gastroenterology. Likewise, the biomaterialist should become aware of the specific tasks that the biomaterials must fulfil when placed within the GI tract, and regard such applications as both a challenge and an incentive for progressing the research in this field.

The Use of Biomaterials in Gastrointestinal Endoscopy

“…Mechanical hemostasis in endoscopy is usually performed by using through the scope or over the scope clips, as well as detachable loops. Chemical hemostasis can be obtained from biomaterial, which are synthetic or natural substances that interact with the body, to replace tissues or augment its functions such as hemostasis and wound healing [6,11,12]. Biologically active materials such as thrombin and fibrin or absorbable products such as gelatins, collagen and oxidized cellulose have been used.…”

“…It is recommended to flush the catheter immediately after acrylate use to prevent crystallization of the glue in the delivery needle. Dilution of the acrylate with lipiodol is also recommended to prevent potential clogging of the endoscopic channel [11,18].…”

“…This combination has the advantage of prolonging the polymerization time, controlling the speed of solidification, reducing the risk of embolization and opacifying the liquid, which allows it to be radio-opaque under fluoroscopy. However, injection of undiluted cyanoacrylate is also performed [11,88].…”

“…The tip of the endoscope and the accessory channel can be treated with silicone oil to prevent endoscopic damage, other studies have used Teflon catheters. Some studies also suggest that spraying acrylate directly over the bleeding point might be better than injection [11,18]. A standardized injection technique was developed for the use of acrylate, performed using a Luer lock injection needle catheter.…”

“…After injection, the vessel plug formed by the polymer of acrylate will be expelled from the varix as early as one week and up to a year after the procedure and rebleeding may occur [11]. Although rarely reported, the needle can get trapped in the varix due to rapid polymerization of the acrylate with inability to withdrawn the needle from the varix and/or unroofing of the varix [70].…”