Optimising the biocompatibility of 3D printed photopolymer constructs in vitro and in vivo

Abstract

3D printing is a rapid and accessible fabrication technology that engenders creative custom design solutions for cell scaffolds, perfusion systems and cell culture systems for tissue engineering. Critical to its success is the biocompatibility of the materials used, which should allow long-term tissue culture without affecting cell viability or inducing an inflammatory response for in vitro and in vivo applications. Polyjet 3D printers offer arguably the highest resolution with the fewest design constraints of any commercially available 3D printing systems. Although widely used for rapid-prototyping of medical devices and 3D anatomical modelling, polyjet printing has not been adopted by the tissue engineering field, largely due to the cytotoxicity of leachates from the printed parts. Biocompatibility in the context of cell culture is not commonly addressed for polyjet materials, as they tend to be optimised for their ability to fabricate complex structures. In order to study the potential issues surrounding the leaching of toxins, we prepared cell culture substrates using the commercially available MED610 photopolymer. The substrates were cleaned using either the manufacturer-specified ‘biocompatible’ washing procedures, or a novel protocol incorporating a sonication in isopropanol and water step. We then compared the effectiveness of these both in vitro and in vivo. Using primary mouse myoblast cultures, the manufacturer’s protocol led to inconsistent and poorer cell viability when compared to the sonication protocol (p = 0.0002 at 48 h after indirect exposure). Subdermal implantation of MED610 into nude rats demonstrated a significant foreign body response with a greater number of giant cells (p = 0.0161) and foreign bodies (p = 0.0368) when compared to the sonication protocol, which was comparable to the control (sham) groups. These results present an improved, cytocompatible cleaning protocol of printable photopolymers to facilitate creative 3D-printed custom designs for cell culture systems for both in vitro and in vivo tissue engineering applications.

3D Printing of Cell Culture Devices: Assessment and Prevention of the Cytotoxicity of Photopolymers for Stereolithography

“…However, this again requires customizing the initial resin. Other options to reduce the cytotoxicity of a resin is post-processing with supercritical carbon dioxide [ 48 ], sonication of the material in isopropanol [ 49 ], or 10 days of incubation in cell growth medium [ 24 ] to leach harmful chemicals.…”

Rapid Fabrication of Sterile Medical Nasopharyngeal Swabs by Stereolithography for Widespread Testing in a Pandemic

“…[ 38 ] Although biocompatibility resists precise definition in areas like tissue engineering, [ 39 ] in dentistry, an extended history of biocompatibility tests and protocols have been designed for local (mucosal and pulpal toxicity) and systemic (allergic, estrogenic, mutagenicity, and more) adverse reactions in vitro, in animals, in clinical studies, as well as occupational cyclic exposure. [ 40–44 ] One notable biocompatible acute toxicity assessment test is performed on fish embryos, where their stages of development are observed for chemical effects from exposure to the material over time. [ 45 ] Furthermore, the effects of the photo‐hardening transition from liquid to solid resin have also been studied for a variety of conditions, such as shrinkage, irradiation, or cure depth effects.…”

Three-Dimensional Printed Devices in Droplet Microfluidics

“…There are many biological and medical applications based on droplet microfluidics, and therefore material biocompatibility of droplet microfluidic devices is a primary concern. A significant number of studies on the conventional material biocompatibility were conducted, while only a small quantity of biocompatibility studies and reviews on 3DP materials were reported [113,114,115]. Generally, devices fabricated by extrusion-based 3DP have better biocompatibility than ones created by vat photopolymerization 3DP [116].…”