Perfusable Vascular Network with a Tissue Model in a Microfluidic Device

Abstract

A spheroid (a multicellular aggregate) is regarded as a good model of living tissues in the human body. Despite the significant advancement in the spheroid cultures, a perfusable vascular network in the spheroids remains a critical challenge for long-term culture required to maintain and develop their functions, such as protein expressions and morphogenesis. The protocol presents a novel method to integrate a perfusable vascular network within the spheroid in a microfluidic device. To induce a perfusable vascular network in the spheroid, angiogenic sprouts connected to microchannels were guided to the spheroid by utilizing angiogenic factors from human lung fibroblasts cultured in the spheroid. The angiogenic sprouts reached the spheroid, merged with the endothelial cells co-cultured in the spheroid, and formed a continuous vascular network. The vascular network could perfuse the interior of the spheroid without any leakage. The constructed vascular network may be further used as a route for supply of nutrients and removal of waste products, mimicking blood circulation in vivo. The method provides a new platform in spheroid culture toward better recapitulation of living tissues.

Three-dimensional tissue model in direct contact with an on-chip vascular bed enabled by removable membranes

“…The total cell number (25 000 cells/ spheroid) was adopted to obtain a spheroid with a diameter of 400 μm, in accordance with our previous study. 16,17 The diameter was small enough to supply oxygen and nutrients to the inside of the spheroid as they are diffused up to 200 μm. 29…”

“…14 Previously, Kim et al reported the construction of a perfusable vascular network in a microfluidic device based on the self-organising functions of human umbilical vein endothelial cells (HUVECs). 15 In addition, 3D tissues such as lung fibroblast, [16][17][18] neuron, 19 and tumour 20 spheroids have been co-cultured with a vascular network. Typically, microfluidic devices contain multiple parallel channels that are separated by micro-posts: 3D tissues are introduced into one of the channels with a hydrogel.…”

“…Firstly, 3D tissues are required to provide angiogenic factors in most self-organising models, wherein ECs and a 3D tissue are simultaneously introduced into a device, and growth factors secreted by the tissue induce vascular formation. [16][17][18][19][20] Therefore, 3D tissues without the ability to induce neovascularisation cannot produce a co-culture model with a vascular network using current self-organising models. The second major issue involves the interaction between vascular networks and 3D tissues, which are closely localised in vivo in contact with the extracellular matrix (ECM), which mediates a uniform gradient of growth factors, nutrients, and oxygen to support tissue growth.…”

“…In this study, we used a 3D tissue model spheroid composed of HUVECs and hLFs, which has previously been shown to induce angiogenic behaviour in microfluidic devices. 16,17,20 The spheroid was cultured on the vascular bed under static conditions, and the vascular connection between them was observed. We also demonstrated the applicability of our system using a spheroid containing cells from alveolar soft part sarcoma (ASPS), a rare, slow-growing, and highly metastatic sarcoma that affects adolescents and young adults.…”

Organoid Models for Precision Cancer Immunotherapy

“…Therefore, using human tumor organoid models is necessary to tackle these limitations. Indeed, organoid models can properly recapitulate the tumor (immune) microenvironment by preserving tissue architecture, endogenous stromal components including various immune cells, or by adding exogenous immune cells, vasculature, and other components ( 23 – 29 ). Therefore, PDO culture systems could model immunotherapy responses and facilitate the immunotherapy preclinical testing.…”