Emerging bone tissue engineering via Polyhydroxyalkanoate (PHA)-based scaffolds.

The ability to model CNS tissues in vitro for in vivo transplantation has the potential to be of critical importance in a variety of medical conditions such as spinal cord injury, traumatic brain injury, stroke, and degenerative neurologic disease. Our approach to generating functional CNS tissue constructs relies on a “multiprong” combination of sophisticated 3D bioprinting and cell culture expertise. Here, as an example for utilizing novel 3D neurobioprinting, we have devised a method to model the cytoarchitecture of spinal cord tissue.

Supporting data for 3D Printed Stem-Cell Derived Neural Progenitors Generate Spinal Cord Scaffolds

Increasing public awareness of foodborne illnesses, factory farming and the ecological footprint of the meat industry, has generated the need for animal-free meat alternatives. In the last decade, scientists have begun to leverage the knowledge and tools accumulated in the fields of stem cells and tissue engineering towards the development of cell-based meat (i.e., clean meat). In tissue engineering, the physical and biochemical features of the native tissue can be mimicked; cells and biomaterials are integrated under suitable culture conditions to form mature tissues. More specifically, in skeletal muscle tissue engineering, a plurality of cell types can be co-cultured on a 3D scaffold to generate muscle fibers, blood vessels and a dense extracellular matrix (ECM). This review focuses on tissue engineering of skeletal muscle and the adjustments needed for clean meat development. We discuss the skeletal muscle structure and composition, and elaborate on cell types from farm animals that have the potential to recapitulate the muscle ECM, blood vessels, muscle fibers and fat deposits. We also review relevant biomaterials, primarily for fabricating scaffolds that can mimic the intramuscular connective tissues, as well as gene expression studies on the biological pathways that influence meat quality.

/pdf/tissue-engineering-for-clean-meat-production-3hznnmiva9.pdf

Tissue Engineering for Clean Meat Production

Human organoids, self-organized and differentiated from homogenous pluripotent stem cells (PSC), replicate the key structural and functional characteristics of their in vivo counterparts. Despite the rapid advancement of organoid technology and its diverse applications, major limitations in achieving truly in vivo like functionality have been the lack of matured structural organization and constraints on tissue size, both of which are direct consequences of lacking a functional vasculature. In the absence of perfusable vessels, a core region within organoids quickly becomes necrotic during development due to increased metabolic demands that cannot be met by diffusion alone. Thus, incorporating functional vasculature in organoid models is indispensable for their growth in excess of several hundred microns and maturaturation beyond the embryonic and fetal phase. Here, we review recent advancements in vascularizing organoids and engineering in vitro capillary beds, and further explore strategies to integrate them on a microfluidic based platform, aiming for establishing perfused vasculature throughout organoids in vitro.

/pdf/vascularized-organoids-on-a-chip-strategies-for-engineering-15ifeqnzyx.pdf

Vascularized organoids on a chip: strategies for engineering organoids with functional vasculature

A novel, pure, synthetic material is presented that promotes the repair of full-thickness skin wounds. The active component is tropoelastin and leverages its ability to promote new blood vessel formation and its cell recruiting properties to accelerate wound repair. Key to the technology is the use of a novel heat-based, stabilized form of human tropoelastin which allows for tunable resorption. This implantable material contributes a tailored insert that can be shaped to the wound bed, where it hydrates to form a conformable protein hydrogel. Significant benefits in the extent of wound healing, dermal repair, and regeneration of mature epithelium in healthy pigs are demonstrated. The implant is compatible with initial co-treatment with full- and split-thickness skin grafts. The implant's superiority to sterile bandaging, commercial hydrogel and dermal regeneration template products is shown. On this basis, a new concept for a prefabricated tissue repair material for point-of-care treatment of open wounds is provided.

/pdf/tropoelastin-implants-that-accelerate-wound-repair-28epplx9wf.pdf

Tropoelastin Implants That Accelerate Wound Repair

A multitude of cell screening assays for diagnostic and research applications rely on quantitative measurements of a sample in the presence of different reagent concentrations. Standard methods rely on microtiter plates of varying well density, which provide simple and standardized sample addressability. However, testing hundreds of chemical dilutions requires complex automation, and typical well volumes of microtiter plates are incompatible with the analysis of a small number of cells. Here, we present a microfluidic device for creating a high-resolution chemical gradient spanning 200 nanoliter wells. Using air-based shearing, we show that the individual wells can be compartmentalized without altering the concentration gradient, resulting in a large set of isolated nanoliter cell culture wells. We provide an analytical and numerical model for predicting the concentration within each culture chamber and validate it against experimental results. We apply our system for the investigation of yeast cell metab...

Nanoliter Cell Culture Array with Tunable Chemical Gradients

https://www.onlinelibrary.wiley.com/doi/pdf/10.1002/adfm.202008687

Engineered Vascularized Flaps, Composed of Polymeric Soft Tissue and Live Bone, Repair Complex Tibial Defects

The key to understanding, harnessing, and manipulating natural biological processes for the benefit of tissue engineering lies in providing a controllable dynamic environment for tissue development in vitro while being able to track cell activity in real time. This work presents a multi-channel bioreactor specifically designed to enable on-line imaging of fluorescently labeled cells embedded in replicated 3D engineered constructs subjected to different flow conditions. The images are acquired in 3D using a standard upright confocal microscope and further analyzed and quantified by computer vision. The platform is used to characterize and quantify the pace and directionality of angiogenic processes induced by flow. The presented apparatus bears considerable potential to advance scientific research, from basic research pursuing the effect of flow versus static conditions on 3D scaffolds and cell types, to clinically oriented modeling in drug screening and cytotoxicity assays.

/pdf/multi-flow-channel-bioreactor-enables-real-time-monitoring-1aawjg9pp2.pdf

Multi-flow channel bioreactor enables real-time monitoring of cellular dynamics in 3D engineered tissue.

Engineering implantable, functional, thick tissues requires designing a hierarchical vascular network. 3D bioprinting is a technology used to create tissues by adding layer upon layer of printable biomaterials, termed bioinks, and cells in an orderly and automatic manner, which allows for creating highly intricate structures that traditional tissue engineering techniques cannot achieve. Thus, 3D bioprinting is an appealing in vitro approach to mimic the native vasculature complex structure, ranging from millimetric vessels to microvascular networks. Advances in 3D bioprinting in granular hydrogels enabled the high-resolution extrusion of low-viscosity extracellular matrix-based bioinks. This work presents a combined 3D bioprinting and sacrificial mold-based 3D printing approach for fabricating engineered vascularized tissue flaps. 3D bioprinting of endothelial and support cells using recombinant collagen-methacrylate bioink within a gelatin support bath is utilized for the fabrication of a self-assembled capillary network. This printed microvasculature is assembled around a mesoscale vessel-like porous scaffold, fabricated using a sacrificial 3D printed mold, and is seeded with endothelial cells. This assembly induces the endothelium of the mesoscale vessel to anastomose with the surrounding capillary network, establishing a hierarchical vascular network within an engineered tissue flap. The engineered flap is then directly implanted by surgical anastomosis to a rat femoral artery using a cuff technique. The described methods can be expanded for the fabrication of various vascularized tissue flaps for use in reconstruction surgery and vascularization studies.

Ariel A. Szklanny

Papers

Nanoliter Cell Culture Array with Tunable Chemical Gradients

Engineered Vascularized Flaps, Composed of Polymeric Soft Tissue and Live Bone, Repair Complex Tibial Defects

Multi-flow channel bioreactor enables real-time monitoring of cellular dynamics in 3D engineered tissue.

Fabrication of Engineered Vascular Flaps using 3D Printing Technologies.