Strategies for vascularization of polymer scaffolds

Abstract

Biocompatible, degradable polymer scaffolds combined with cells or biological signals are being investigated as alternatives to traditional options for tissue reconstruction and transplantation. These approaches are already in clinical use as engineered tissues that enhance wound healing and skin regeneration. The continued enhancement of these material strategies is highly dependent on the ability to promote rapid and stable neovascularization (new blood vessel formation) within the scaffold. Whereas neovascularization therapies have shown some promise for the treatment of ischemic tissues, vascularization of polymer scaffolds in tissue engineering strategies provides a unique challenge owing to the volume and the complexity of the tissues targeted. In this article, we examine recent advances in research focused on promoting neovascularization in polymer scaffolds for tissue engineering applications. These approaches include the use of growth factors, cells, and novel surgical approaches to both enhance and control the nature of the vascular networks formed. The continued development of these approaches may lead to new tissue engineering strategies for the generation of skin and other tissues or organs.

Figure 1

A mutlilayer alginate microbead in which each layer contains fluorescently labeled albumin. The composition of each layer can be controlled allowing for distinct release kinetics of proteins encapsulated in each of the layers.

Figure 2

PEG hydrogel patterns formed by interfacial photopolymerization and non-contact photolithography. Vascular hydrogel patterns (A) and (B). Multilayer hydrogels with distinct pattern formation in each layer (1, 2, 3, indicate first, second and third hydrogel layers, respectively). (C) Top view (D) side view. Adapted and reprinted with permission from Papavasiliou G. et al. [43].

Figure 3

Microchannel generated in poly(ethylene glycol) hydrogels generated by selective degradation of patterned microstructures.