Projection-based stereolithography for direct 3D printing of heterogeneous ultrasound phantoms.

Modern ultrasound (US) imaging is increasing its clinical impact, particularly with the introduction of US-based quantitative imaging biomarkers. Continued development and validation of such novel imaging approaches requires imaging phantoms that recapitulate the underlying anatomy and pathology of interest. However, current US phantom designs are generally too simplistic to emulate the structure and variability of the human body.

Blood Flow Within Bioengineered 3D Printed Vascular Constructs Using the Porcine Model.

Recently developed biofabrication technologies are enabling the production of three-dimensional engineered tissues containing vascular networks which can deliver oxygen and nutrients across large tissue volumes. Tissues at this scale show promise for eventual regenerative medicine applications; however, the implantation and integration of these constructs remains poorly studied. Here, we introduce a surgical model for implantation and direct in-line vascular connection of 3D printed hydrogels in a porcine arteriovenous shunt configuration.

Multivascular networks and functional intravascular topologies within biocompatible hydrogels.

Solid organs transport fluids through distinct vascular networks that are biophysically and biochemically entangled, creating complex three-dimensional (3D) transport regimes that have remained difficult to produce and study. We establish intravascular and multivascular design freedoms with photopolymerizable hydrogels by using food dye additives as biocompatible yet potent photoabsorbers for projection stereolithography. We demonstrate monolithic transparent hydrogels, produced in minutes, comprising efficient intravascular 3D fluid mixers and functional bicuspid valves.

Elucidating the role of graft compliance mismatch on intimal hyperplasia using an ex vivo organ culture model.

There is a growing clinical need to address high failure rates of small diameter (<6 mm) synthetic vascular grafts. Although there is a strong empirical correlation between low patency rates and low compliance of synthetic grafts, the mechanism by which compliance mismatch leads to intimal hyperplasia is poorly understood. To elucidate this relationship, synthetic vascular grafts were fabricated that varied compliance independent of other graft variables.

Ultrahigh-throughput Generation and Characterization of Cellular Aggregates in Laser-ablated Microwells of Poly(dimethylsiloxane).

Aggregates of cells, also known as multicellular aggregates (MCAs), have been used as microscale tissues in the fields of cancer biology, regenerative medicine, and developmental biology for many decades. However, small MCAs (fewer than 100 cells per aggregate) have remained challenging to manufacture in large quantities at high uniformity. Forced aggregation into microwells offers a promising solution for forming consistent aggregates, but commercial sources of microwells are expensive, complicated to manufacture, or lack the surface packing densities that would significantly improve MCA production.

Open-Source Selective Laser Sintering (OpenSLS) of Nylon and Biocompatible Polycaprolactone.

Selective Laser Sintering (SLS) is an additive manufacturing process that uses a laser to fuse powdered starting materials into solid 3D structures. Despite the potential for fabrication of complex, high-resolution structures with SLS using diverse starting materials (including biomaterials), prohibitive costs of commercial SLS systems have hindered the wide adoption of this technology in the scientific community. Here, we developed a low-cost, open-source SLS system (OpenSLS) and demonstrated its capacity to fabricate structures in nylon with sub-millimeter features and overhanging regions.

In Vivo Anastomosis and Perfusion of a Three-Dimensionally-Printed Construct Containing Microchannel Networks.

The field of tissue engineering has advanced the development of increasingly biocompatible materials to mimic the extracellular matrix of vascularized tissue. However, a majority of studies instead rely on a multiday inosculation between engineered vessels and host vasculature rather than the direct connection of engineered microvascular networks with host vasculature. We have previously demonstrated that the rapid casting of three-dimensionally-printed (3D) sacrificial carbohydrate glass is an expeditious and a reliable method of creating scaffolds with 3D microvessel networks.

Effect of fetal bovine serum on mineralization in silk fibroin scaffolds.

Fetal bovine serum (FBS) is a common media supplement used in tissue engineering (TE) cultures. The chemical composition of FBS is known to be highly variable between different brands, types or batches and can have a significant impact on cell function. This study investigated the influence of four different FBS types in osteogenic or control medium on mineralization of acellular and cell-seeded silk fibroin (SF) scaffolds.