Recent advances in 3D printing: vascular network for tissue and organ regeneration

Abstract

Over the past years, the fabrication of adequate vascular networks has remained the main challenge in engineering tissues due to technical difficulties, while the ultimate objective of tissue engineering is to create fully functional and sustainable organs and tissues to transplant in the human body. There have been a number of studies performed to overcome this limitation, and as a result, 3D printing has become an emerging technique to serve in a variety of applications in constructing vascular networks within tissues and organs. 3D printing incorporated technical approaches allow researchers to fabricate complex and systematic architecture of vascular networks and offer various selections for fabrication materials and printing techniques. In this review, we will discuss materials and strategies for 3D printed vascular networks as well as specific applications for certain vascularized tissue and organ regeneration. We will also address the current limitations of vascular tissue engineering and make suggestions for future directions research may take.

Figure 1.

A diagram tree of the 3D printing techniques for vascular network fabrication.

Figure 2.

(a) Schematic illustration of the fabrication process of 3D bioprinted vascularized bone scaffolds with bioactive growth factor nanocoatings. (b) A 3D confocal fluorescence image of hMSCs (green) and HUVECs (red) co-cultured for 5 days. (c) Immunofluorescence images of hMSCs and HUVECs with CD31 antibody for 2 and 4 weeks on different scaffolds. A PLA based control scaffolds (left) and a genipin crosslinked bioactive nanocoating with growth factors (cBCG) based scaffold (right). Scale bars, 100 μm. (d) Mineralization of osteogenic differentiation of hMSCs and hMSCs/HUVECs on PLA and cBCG based scaffolds analyzed by Alizarin red staining. (e) Schematic illustration of a dual 3D bioprinting platform. (f) Schematic representation of the microstructural design of a biomimetic biphasic vascularized bone construct based on a matrix metalloprotease (MMP) sensitive GelMA hydrogel. The evolution of vascular lumen and capillary network formation can be achieved in different regions during the culture period. (g) Computer-aided design (CAD) model of the biphasic vascularized bone construct, including the bone region and vascular channels (left). Microscopic photo image of manufactured vascularized bone construct (right). Red circles show tubular vascular hydrogel regions. (h) A 3D immunofluorescence image of the vascular capillary network with CD31 antibody in the designed different regions of the 10 wt% GelMA hydrogel printed by the dual 3D bioprinting platform after 4 weeks. Scale bar, 50 μm. (i) A 3D immunofluorescence image of a vascular lumen in the 3D bioprinted vascularized bone. Scale bar, 50 μm. Images are adapted from (2, 3).

Figure 3.

(a) 3D printed scaffold before cell seeding. Scale bar, 1 mm. (b) Immunostaining images of vascular network generation in vitro within skeletal muscle construct after one month. Skeletal myoblasts, ECs, and mouse embryonic fibroblasts were tri-cultured. Scale bar, 50 μm. (c) Immunostaining images of in vivo study of the vascularized skeletal model after two weeks of transplantation into immunodeficient mice. The constructs underwent immunostaining with human-specific CD31 antibody. Scale bar, 50 μm. Images are adapted from (75).

Figure 4.

(a) 3D printed vasculature with hollow and interconnected structure after 24 hours of perfusion culture. (b) An immunofluorescence image of 3D printed vasculature (CD 31 antibody and α-smooth muscle actin (α-SMA)) in a dynamic culture condition. (c) An optical microscopic image of dynamic flow in the 3D printed vasculature. (d) An optical microscopic image of anisotropic honeycomb constructs of 3D bioprinted vascularized cardiac patch. (e) A fluorescence image of 3D bioprinted vascularized cardiac patch (cardiomyocyte (CMs) and ECs).(f) in vivo implantation of 3D bioprinted vascularized cardiac patch into infarcted heart of mice.

Figure 5.

(a) Side view of 3D printed liver and extracted liver of a patient, where long, short, and double arrows indicate hepatic artery, hepatic vein, and portal vein, respectively. (b) Right lobes of 3D printed and extracted livers with indications of the hepatic artery (single arrows) and portal vein (double arrows). (c) Cross-sectional views of 3D printed and extracted livers with indications of hepatic vein (single arrows) and portal vein (dotted arrows). Images are adapted from (7).

Figure 6.

(a) A 3D arterial construct of magnetic resonance imaging from a patient. (b) A magnified image of the highlighted region. (c) A magnetic resonance angiography image and (d) 3D printed model of the indicated region with arrows. Images are adapted from (108).