Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5945_Библиотеки_им_академика_М_И_Перельмана

hybrid medical devices. Esoxx

is a hybrid medical device employed as mucosal bar-

rier for the treatment of gastroesophageal reflux symptoms based on HA and CS

embedded in Lutrol

F 127, a poloxamer with bioadhesive properties [52]. HA/

CSbased medical devices are also employed as injectable hydrogel to treat osteoar-

thritic (OA) knee, as reported for Structovial CS

material device fields for different applications, even if, considering its main role as an anticoagulant, the use of heparinbased medical devices is mainly focused on bloodcontacting materials[61, 62]. Temporary or permanent devices like hemodi­alysis catheters, coronary or vascular stents and grafts, bypass devices, and extracor­poreal circulation devices exploit heparincoated materials[57, 62–64]. The two general methods employed for the development of heparincoated devices are based on eluting technologies and noneluting technologies. Eluting technologies include all the approaches in which heparin is released in a controlled way, taking advan­tage of noncovalent coatings based on physical or ionic interactions [62, 65, 66]. These methods are employed when heparin delivery is needed to prevent acute and local devicerelated blood clots. The other approach is based on the covalent func­tionalization of the medical device surface with heparin[67, 68]. This approach is desirable when longterm thromboresistance is needed at the material surface. Different conjugation methodologies exploit the direct coupling of complementary functional groups already present in heparin and the material surface counterpart, or alternatively introduce new chemoselective orthogonal functional groups and properly tailored linkers to better control heparin exposition and consequently the antithrombotic activity. The chemical nature of the medical device will influence the choice in light of the functional groups eventually present at the surface or, alternatively, introducible upon proper treatment. The most employed conjugation methodologies are based on carbodiimide chemistry, exploiting the carboxyl group of heparin, or oxidation mediated by periodate, for controlled oxidative degradation to generate some aldehydes[69]. A coating material based on heparin, polyethylene oxide, and sulphonate groups covalently conjugated to hydrophilic modified poly-

biomedical applications. Furthermore, they can be properly modified to control the properties and final morphologies of a large plethora of formulations. The main nonhuman polysaccharides exploited for biomedical devices are alginates, carra­geenan, and fucoidan (derived from algae), dextran, pullulan, and gellan (derived from microbes), and chitosan (derived from animals) (see Figure8.3).

Strategies like genomic editing and chemical immunosuppression are under investigation to limit xenoantibody production and avoid undesirable early graft rejection[122, 124, 125]. In December 2020, transgenic pigs with depletion of α  Gal–named GalSafe pigs–were approved by FDA for human food consumption and possible biomedical uses [126]. Decellularized animal tissues were also developed with the aim to limit xenoantigens from cellular components; how­ever, the immunological response of these devices is often still in place, probably due to the glycosylation of ECM components[125]. The most efficient solution is probably a coating able to mask the xenoantigens responsible for immunore­sponse. Glutaraldehyde fixation [127, 128] is an option. Treatment of animal derived biological tissues with a low concentration of glutaraldehyde enhances structural performance, maintains sterility, and reduces antigenicity. Although