(C-83) Development of muscle and vascular model in microfluidic chip for muscle disease modeling and drug screening

Muscles are distributed throughout the body and control numerous functions. Therefore, even small failures through muscle diseases can be fatal if accumulated for a long time. Amyotrophic lateral sclerosis (ALS), well known as a rare muscle disease, causes muscle atrophy, paralysis, and serious death. In addition, as attention in aging increases, sarcopenia, which is associated with chronic kidney disease (CKD) and diabetes, is also attracting attention. In particular, recently, many studies have been conducted to emulate the muscle diseases by creating muscle bands in microfluidic systems. However, in these studies, it was not possible to implement the drug screening through blood vessel and there is a limit to connecting with other organ chip platforms to study the interaction or increasing the size of the muscle band itself. Therefore, in this study, we focus on the development of model in which muscles and blood vessels are integrated to simulate drug screening and actual muscle diseases. The development of the model will proceed by connecting blood vessels surrounding a muscle band created by contracting gel, which will enable drug screening through blood vessels to the muscle model that can respond to external stimuli.

The co-culture model implements combination of vasculogenesis with existing muscle band formation methods. First, microfluidic chips are manufactured in the form of two pillars in the center to allow the muscle force generation measurement. Skeletal muscle cells (C2C12) are mixed in the hydrogel (collagen gel mixed with Matrigel), seeded, and the muscle band is formed through gel contraction. Afterwards, blood vessels are formed around the muscles through vasculogenesis via double seeding method which re-seeds human umbilical vascular endothelial cells (HUVEC) by mixing them in the gel (fibrin gel mixed with Matrigel) into the area where muscle band is formed.

In order to improve the existing muscle band production method, stable muscle band production conditions were found by changing experimental conditions such as gel composition and cell density. And to reduce the contraction effect of fibrin gel when seeding HUVEC cells after muscle seeding, Matrigel was mixed with existing gel, and it was verified that vasculogenesis can occur under the specified conditions. Finally, by forming a muscle band with gel contraction during the seven-day culture period after the seeding of muscle cells and double-seeding HUVECs, the muscle & vascular model was created in which capillaries spread and distributed around the muscle band.

In this work, we implemented a muscle and vasculature co-culture model on a microfluidic chip with blood vessels spread around the muscle through the formation of stable muscle bands and double seeding methods. Drug treatment or physical stress can be applied to muscle or blood vessels to simulate diseases in the muscle and vascular model, and drug screening into muscles through blood vessels will be possible when developing drugs for treatment in muscle disease research.