Polyurethane elastomer: A new material for the visualization of cadaveric blood vessels

Abstract

A multitude of various materials are available for the visualization of cadaveric vessels, ranging from natural materials like gelatin and latex to synthetic materials like silicone rubber or acrylates. To achieve a detailed overview of the vascular architecture in microvascular studies in experimental flap surgery, the injected material should have low viscosity to assure perfusion of even the smallest vessels. In addition, the material ideally should have either no or only minimal shrinkage, and should harden within a reasonable time, but retain sufficient elasticity and resistance to withstand tearing off the delicate vessels during subsequent dissection or casting. Because none of the available injection materials adequately combines these attributes, we evaluated the polyurethane elastomer "PU4ii" in latissimus dorsi muscles as a new material for the visualization of cadaveric vessels in comparison with the frequently used silicone rubber. The dissection of vessels injected with PU4ii proved easy largely because of its exceptional hardness. Even if not visible before dissection, the completely perfused vessels were easily palpated in the surrounding fat or muscle tissue of the microsurgical latissimus dorsi model. Despite the significantly higher hardness of PU4ii over silicone rubber (98 Sh-A vs. 12 Sh-A), PU4ii proved enough elasticity (20-25 N/mm(2) E modulus) and a high tear resistance (64-68 N/mm vs. 15 N/mm) preventing breakage during dissection even within the smallest vessels. In contrast to silicone rubber (and latex or gelatin), the high corrosion resistance and form stability of PU4ii also allowed building of casts for qualitative examination by scanning electron microscopy and quantitative analysis of the vessel density using micro-computed tomography with accurate 3D representation. In this study we show that PU4ii has physical characteristics that make it a multi-purpose material that allows at the same breath an excellent gross visualization of the architecture of cadaveric blood vessels as well as a detailed evaluation of casts by modern microscopic and or radiologic tools. Thus, the new polyurethane elastomer PU4ii is in many respects superior to the widely used silicone rubber and can be strongly recommended as a visualization material for a comprehensive evaluation of cadaveric blood vessels in microsurgery.

Simultaneous 3D visualization and quantification of murine bone and bone vasculature using micro‐computed tomography and vascular replica

“…For the two VCC protocols, a polyurethane-based casting resin (PU4ii, vasQtec, Zurich, Switzerland) was used, which shows low viscosity, timely polymerization, and minimal shrinking and thus, provides high quality casts, including the finest capillaries Meyer et al, 2007). For the VCP protocol, barium sulfate (BaSO 4 ) particles (Sachtleben Chemie GmbH, Duisburg, Germany) with a mean particle size less than 1 lm were dispersed for 10 min using a conical bead mill (Bü hler AG, Uzwil, Switzerland) in suspension.…”

“…For butanone, dichloromethane, and methyl salicylate, the PU became brittle-in particular for dichloromethaneand shrank at the same time. In view of the fact that PU4ii is a polyurethane elastomer (Meyer et al, 2007) and given that solvents can attack plastic, their detrimental influence on PU4ii becomes clear. Ultrasonication, which can help removing fat traces mechanically, was not employed as it can introduce bone damage (Johnson et al, 2000).…”

“…However, quantitative evaluation of bone vascularization in small rodents like mice remains a challenging task due to problems of casting material, specimen preparation as well as tomographic imaging. Recently, a new polyurethane (PU)-based casting material was described Meyer et al, 2007) with improved chemical and physical characteristics that allow less fragile reproduction of vasculature, increasing X-ray opacity, and high reproduction quality. Here, we propose an integrative approach for the simultaneous assessment of murine bone and its vasculature.…”

The interpectoral fascia flap

“…In 20 cadavers, 4 fresh specimens, and 16 specimens fixed with Thiel solution (Thiel, 1992), the trunk of the thoracoacromial arteries was selectively injected with red polyurethane using the technique described by Meyer (Meyer et al, 2007). Of the 20 cadavers, 11 were male and 9 were female.…”

Glutathione-responsive biodegradable poly(urea-urethane)s containing L-cystine-based chain extender

“…Polyurethane, usually prepared through step polymerization of diisocyanate and polyols, possessed a microstructure of alternating soft and hard segments which fulfilled itself with excellent mechanical properties and favorable biocompatibility [2]. In a wide variety of applications as biomaterials, PU was especially utilized in implantable devices such as drug administration carriers [3,4], artificial blood vessels [5,6], heart valves [7][8][9], nucleus prosthesis [10,11], and other tissue engineering materials [12,13]. Some articles have reported biodegradable PU or poly(urea-urethane)s, mainly depending on the soft segment undergoing hydrolytic, enzymatic, and oxidative pathways [14][15][16][17][18], in which hydrolyzation of polyester and oxidation of polyether were the most common pattern [19][20][21].…”