Bioprinting of freestanding vascular grafts and the regulatory considerations for additively manufactured vascular prostheses

Abstract

Vasculature is the network of blood vessels of an organ or body part that allow for the exchange of nutrients and waste to and from every cell, thus establishing a circulatory equilibrium. Vascular health is at risk from a variety of conditions that includes disease and trauma. In some cases, medical therapy can alleviate the impacts of the condition. Intervention is needed in other instances to restore the health of abnormal vasculature. The main approaches to treat vascular conditions are endovascular procedures and open vascular reconstruction that often requires a graft to accomplish. However, current vascular prostheses have limitations that include size mismatch with the native vessel, risk of immunogenicity from allografts and xenografts, and unavailability of autografts. In this review, we discuss efforts in bioprinting, an emerging method for vascular reconstruction. This includes an overview of 3D printing processes and materials, graft characterization strategies and the regulatory aspects to consider for the commercialization of 3D bioprinted vascular prostheses.

Figure 1.

Blood vessel structural features depicting the thicker wall of the artery relative to the vein because of the higher blood flow pressure in the arteries. Reproduced from [164] with permission. Download for free at http://cnx.org/contents/14fb4ad7-39a1-4eee-ab6e-3ef2482e3e22@8.24.

Figure 2.

3D printing process categories of the American Society for Testing and Materials (ASTM). (A) Material extrusion. Adapted with permission from [165]. (B) Material jetting. Adapted with permission from [165]. (C) Powder bed fusion, specifically the EBM process. Adapted with permission from [165]. (D) Binder jetting. Adapted with permission from [165]. (E) Directed energy deposition. Adapted with permission and photo courtesy of Sciaky, Inc. [166]. (F) Vat photopolymerization, specifically the SLA process. Adapted with permission from [165]. (G) Sheet lamination, specifically the LOM process. Adapted with permission from Manufacturing Guide [167].

Figure 3.

FDA framework for the regulation of medical devices highlighting the regulatory pathway for vascular prostheses currently on the market. Specifically, current vascular prostheses are categorized as Class II medical devices with “special controls”and should align with the nonbinding recommendations provided by the FDA in the “Guidance Document for Vascular Prostheses 510(k) Submissions - Guidance for Industry and FDA staff’ [116, 157]