The fusion of tissue spheroids attached to pre-stretched electrospun polyurethane scaffolds

Abstract

Effective cell invasion into thick electrospun biomimetic scaffolds is an unsolved problem. One possible strategy to biofabricate tissue constructs of desirable thickness and material properties without the need for cell invasion is to use thin (<2 µm) porous electrospun meshes and self-assembling (capable of tissue fusion) tissue spheroids as building blocks. Pre-stretched electrospun meshes remained taut in cell culture and were able to support tissue spheroids with minimal deformation. We hypothesize that elastic electrospun scaffolds could be used as temporal support templates for rapid self-assembly of cell spheroids into higher order tissue structures, such as engineered vascular tissue. The aim of this study was to investigate how the attachment of tissue spheroids to pre-stretched polyurethane scaffolds may interfere with the tissue fusion process. Tissue spheroids attached, spread, and fused after being placed on pre-stretched polyurethane electrospun matrices and formed tissue constructs. Efforts to eliminate hole defects with fibrogenic tissue growth factor-β resulted in the increased synthesis of collagen and periostin and a dramatic reduction in hole size and number. In control experiments, tissue spheroids fuse on a non-adhesive hydrogel and form continuous tissue constructs without holes. Our data demonstrate that tissue spheroids attached to thin stretched elastic electrospun scaffolds have an interrupted tissue fusion process. The resulting tissue-engineered construct phenotype is a direct outcome of the delicate balance of the competing physical forces operating during the tissue fusion process at the interface of the pre-stretched elastic scaffold and the attached tissue spheroids. We have shown that with appropriate treatments, this process can be modulated, and thus, a thin pre-stretched elastic polyurethane electrospun scaffold could serve as a supporting template for rapid biofabrication of thick tissue-engineered constructs without the need for cell invasion.

Patterning of tissue spheroids biofabricated from human fibroblasts on the surface of electrospun polyurethane matrix using 3D bioprinter

“…This fact is in good accordance with previous published reports about attachment, spreading and fusion of tissue spheroids placed manually on electrospun matrices [21,22] . The main advantage in using 3D bioprinter for automated placing of tissue spheroids is a possibility to create regular pattern of their redistribution and, thus, to control the resulted thickness of bioprinted tissue construct.…”

“…Fabrication of nano-/microfibrous synthetic scaffolds by electrospinning is one of popular application of nanotechnology in tissue engineering [19,20] . It has been demonstrated that tissue spheroids can attach, spread and fuse on synthetic electrospun matrices [21,22] . Moreover, recently reported magnetic functionalization of electrospun synthetic matrices with magnetic nanoparticles [23] as well as biofabrication of tissue spheroids from cells labelled with magnetic nanoparticles [24][25][26][27] allow the development of magnetic forcesdriven biofabrication and even 3D magnetic bioprinting based on principles of magnetic levitation [28][29][30] .…”

Mesoporous Silica-Layered Biopolymer Hybrid Nanofibrous Scaffold: A Novel Nanobiomatrix Platform for Therapeutics Delivery and Bone Regeneration

“…[36][37][38][39][40][41][42] For the regeneration of hard tissues like bone and tooth structure, bioactive inorganic phases have been attractive through providing chemical and/or physical bone-bioactive cues to the cells involved in osteogenic processes. Inorganic nanofibers have poor mechanical stability and are not effective when used as cell supporting matrices.…”

The Self-Assembling Process and Applications in Tissue Engineering

“…Layer-by-layer composition in this study allowed for the design of a double-layered vascular wall exhibiting patterns of smooth muscle cell and fibroblast organization (61). Interestingly, placement of stem cell-based spheroids on a pre-stretched electrospun scaffold resulted in incomplete fusion and hole formation in tissue-engineered vessels, suggesting that the scaffold may impede fusion (62). Though burst pressure as a functional parameter was not assessed in these spheroid-based studies, the results demonstrate the ability to finely control structural architecture in vascular tissue engineering and achieve small-diameter vessels (<5mm).…”