Collagen and Beyond: A Comprehensive Comparison of Human ECM Properties Derived from Various Tissue Sources for Regenerative Medicine Applications.

Collagen, along with proteoglycans, glycosaminoglycans, glycoproteins, and various growth factors, forms the extracellular matrix (ECM) and contributes to the complexity and diversity of different tissues. Herein, we compared the physicochemical and biological properties of ECM hydrogels derived from four different human tissues: skin, bone, fat, and birth. Pure human collagen type I hydrogels were used as control.

3D bioprinting of an implantable xeno-free vascularized human skin graft.

Bioengineered tissues or organs produced using matrix proteins or components derived from xenogeneic sources pose risks of allergic responses, immune rejection, or even autoimmunity. Here, we report successful xeno-free isolation, expansion, and cryopreservation of human endothelial cells (EC), fibroblasts (FBs), pericytes (PCs), and keratinocytes (KCs). We further demonstrate the bioprinting of a human skin substitute with a dermal layer containing xeno-free cultured human EC, FBs, and PCs in a xeno-free bioink containing human collagen type I and fibronectin layered in a biocompatible polyglycolic acid mesh and subsequently seeded with xeno-free human KCs to form an epidermal layer.

Native human collagen type I provides a viable physiologically relevant alternative to xenogeneic sources for tissue engineering applications: A comparative in vitro and in vivo study.

Xenogeneic sources of collagen type I remain a common choice for regenerative medicine applications due to ease of availability. Human and animal sources have some similarities, but small variations in amino acid composition can influence the physical properties of collagen, cellular response, and tissue remodeling. The goal of this work is to compare human collagen type I-based hydrogels versus animal-derived collagen type I-based hydrogels, generated from commercially available products, for their physico-chemical properties and for tissue engineering and regenerative medicine applications.

3D printed mitral valve models: affordable simulation for robotic mitral valve repair.

Objectives: 3D printed mitral valve (MV) models that capture the suture response of real tissue may be utilized as surgical training tools. Leveraging clinical imaging modalities, 3D computerized modelling and 3D printing technology to produce affordable models complements currently available virtual simulators and paves the way for patient- and pathology-specific preoperative rehearsal.

Methods: We used polyvinyl alcohol, a dissolvable thermoplastic, to 3D print moulds that were casted with liquid platinum-cure silicone yielding flexible, low-cost MV models capable of simulating valvular tissue.

Chitosan fibers with improved biological and mechanical properties for tissue engineering applications.

The low mechanical properties of hydrogel materials such as chitosan hinder their broad utility for tissue engineering applications. Previous research efforts improved the mechanical properties of chitosan fiber through chemical and physical modifications; however, unfavorable toxicity effects on cells were reported. In this paper, we report the preparation of chitosan fibers with improved mechanical and biocompatibility properties.

Hybrid printing of mechanically and biologically improved constructs for cartilage tissue engineering applications.

Bioprinting is an emerging technique used to fabricate viable, 3D tissue constructs through the precise deposition of cells and hydrogels in a layer-by-layer fashion. Despite the ability to mimic the native properties of tissue, printed 3D constructs that are composed of naturally-derived biomaterials still lack structural integrity and adequate mechanical properties for use in vivo, thus limiting their development for use in load-bearing tissue engineering applications, such as cartilage. Fabrication of viable constructs using a novel multi-head deposition system provides the ability to combine synthetic polymers, which have higher mechanical strength than natural materials, with the favorable environment for cell growth provided by traditional naturally-derived hydrogels.

Complex heterogeneous tissue constructs containing multiple cell types prepared by inkjet printing technology.

This study was designed to develop a versatile method for fabricating complex and heterogeneous three-dimensional (3D) tissue constructs using simultaneous ink-jetting of multiple cell types. Human amniotic fluid-derived stem cells (hAFSCs), canine smooth muscle cells (dSMCs), and bovine aortic endothelial cells (bECs), were separately mixed with ionic cross-linker calcium chloride (CaCl(2)), loaded into separate ink cartridges and printed using a modified thermal inkjet printer. The three cell types were delivered layer-by-layer to pre-determined locations in a sodium alginate-collagen composite located in a chamber under the printer.

Improving the mechanical properties of chitosan-based heart valve scaffolds using chitosan fibers.

Chitosan is being widely studied for tissue engineering applications due to its biocompatibility and biodegradability. However, its use in load-bearing applications is limited due to low mechanical properties. In this study, we investigated the effectiveness of a chitosan fiber reinforcement approach to enhancing the mechanical properties of chitosan scaffolds.