Efficient in vivo vascularization of tissue-engineering scaffolds

Abstract

The success of tissue engineering depends on the rapid and efficient formation of a functional blood vasculature. Adult blood vessels comprise endothelial cells and perivascular mural cells that assemble into patent tubules ensheathed by a basement membrane during angiogenesis. Using individual vessel components, we characterized intra-scaffold microvessel self-assembly efficiency in a physiological in vivo tissue engineering implant context. Primary human microvascular endothelial and vascular smooth muscle cells were seeded at different ratios in poly-L-lactic acid (PLLA) scaffolds enriched with basement membrane proteins (Matrigel) and implanted subcutaneously into immunocompromised mice. Temporal intra-scaffold microvessel formation, anastomosis and perfusion were monitored by immunohistochemical, flow cytometric and in vivo multiphoton fluorescence microscopy analysis. Vascularization in the tissue-engineering context was strongly enhanced in implants seeded with a complete complement of blood vessel components: human microvascular endothelial and vascular smooth muscle cells in vivo assembled a patent microvasculature within Matrigel-enriched PLLA scaffolds that anastomosed with the host circulation during the first week of implantation. Multiphoton fluorescence angiographic analysis of the intra-scaffold microcirculation showed a uniform, branched microvascular network. 3D image reconstruction analysis of human pulmonary artery smooth muscle cell (hPASMC) distribution within vascularized implants was non-random and displayed a preferential perivascular localization. Hence, efficient microvessel self-assembly, anastomosis and establishment of a functional microvasculture in the native hypoxic in vivo tissue engineering context is promoted by providing a complete set of vascular components.

Overcoming physical constraints in bone engineering: ‘the importance of being vascularized’

“…Tissue engineering in vitro is severely limited by a number of biological drawbacks related to the huge simplification of the complex architecture of native organs (Hegen et al, 2011). In most animals, this diffusional limitation is overcome by the mass transport of internal fluids (blood) flowing through a vasculature under a pressure generated by one or more pumps (hearts).…”

“…The main challenge in bone engineering is how to exploit the great potentiality of endothelium as a mandatory vehicle to drive prevascularization of scaffolds as well as the angiogenesis of an implanted bone (Brennan et al, 2013;Chung & Shum-Tim, 2012a;Hegen et al, 2011;Rouwkema, Rivron, & van Blitterswijk, 2008;Sakaguchi et al, 2013). Indeed, vascularization of engineered bone tissues is still the primary factor limiting their suitability for clinical use.…”

Taking a deep look: modern microscopy technologies to optimize the design and functionality of biocompatible scaffolds for tissue engineering in regenerative medicine

“…As the success of TE depends largely on the rapid and efficient formation of functional blood vessel architectures, some authors used 2-PF to image and analyse scaffold vascularization [131]. PLLA scaffolds (Matrigel-enriched with basement membrane proteins) were seeded with human endothelial and red fluorescent protein (RFP)-expressing smooth muscle cells and implanted subcutaneously into immune-deficient mice.…”

Human Adipose Tissue-Derived SSEA-4 Subpopulation Multi-Differentiation Potential Towards the Endothelial and Osteogenic Lineages

“…13 Previous in vivo studies showed that vascularization within engineered constructs using mature endothelial cells (ECs) improved blood perfusion, cell viability, and their survival after implantation. [14][15][16] However, the limited availability and proliferation capability of mature ECs hinder their use in tissue engineering (TE) approaches. 17 Therefore, it became a priority to find a suitable source of ECs that do not present such constrains and that will be ready-to-use for therapeutic applications.…”