Stem Cells and Scaffolds for Vascularizing Engineered Tissue Constructs

Abstract

The clinical impact of tissue engineering depends upon our ability to direct cells to form tissues with characteristic structural and mechanical properties from the molecular level up to organized tissue. Induction and creation of functional vascular networks has been one of the main goals of tissue engineering either in vitro, for the transplantation of prevascularized constructs, or in vivo, for cellular organization within the implantation site. In most cases, tissue engineering attempts to recapitulate certain aspects of normal development in order to stimulate cell differentiation and functional tissue assembly. The induction of tissue growth generally involves the use of biodegradable and bioactive materials designed, ideally, to provide a mechanical, physical, and biochemical template for tissue regeneration. Human embryonic stem cells (hESCs), derived from the inner cell mass of a developing blastocyst, are capable of differentiating into all cell types of the body. Specifically, hESCs have the capability to differentiate and form blood vessels de novo in a process called vasculogenesis. Human ESC-derived endothelial progenitor cells (EPCs) and endothelial cells have substantial potential for microvessel formation, in vitro and in vivo. Human adult EPCs are being isolated to understand the fundamental biology of how these cells are regulated as a population and to explore whether these cells can be differentiated and reimplanted as a cellular therapy in order to arrest or even reverse damaged vasculature. This chapter focuses on advances made toward the generation and engineering of functional vascular tissue, focusing on both the scaffolds - the synthetic and biopolymer materials - and the cell sources - hESCs and hEPCs.

Lin28a up‐regulation is associated with the formation of restenosis via promoting proliferation and migration of vascular smooth muscle cells

“…The above evidences presented the similarity to the process of restenosis plaques repair to some extent. Moreover, Lin28a expressed highly in the early stage of angiogenesis and it gradually decreased with the development of vascular maturation 33 . Based on the above evidences, we hypothesize that Lin28a might be involved in restenosis formation.…”

Mesenchymal Stem Cells Increase Neo-Angiogenesis and Albumin Production in a Liver Tissue-Engineered Engraftment

“…A suitable perfusion of metabolically-active tissue requires intimate localization of cells to a dense vasculature in a highly organized manner [ 10 , 11 ]. According these considerations, we have examined recent advances in the field of stem cell and nanotechnology research in order to produce a vascularized and functional tissue-engineered liver graft [ 12 , 13 , 14 , 15 , 16 ]. Advanced tissue engineering strategies were applied through the pre-conditioning of cell-seeded 3D scaffolds in a bioreactor system, followed by their implantation in an animal model.…”

In vitro and in vivo biocompatibility evaluation of a novobiocin stimulus-responsive poly(ethylene glycol)-based hydrogel designed for soft tissue regeneration

“…7 More importantly, in the hydrogel context, PEG molecules are bio-inert 8 and biocompatible, as evidenced by their widespread implementation in drug "PEGylation." 9 Accordingly, the PEG molecule itself is unlikely to present a cytotoxicological threat, if the hydrogel is in contact with or is implanted inside the body.…”