Motor Neuron-Skeletal Muscle Co Culture Model: A Potential Novel in Vitro and Computaional Platform to Investigate Cancer Cachexia

Skeletal muscle is the largest organs in the human body, comprising approximately 45% of total body weight. It is a primary site for glucose uptake (75% uptake) and storage (85%). The connection between motor neuron and skeletal muscle is the crucial final link in the human motor system controlling voluntary muscular movements. Consequently, muscle denervation and re-innervation dramatically alter muscle physiology. Vice versa, there is increasing evidence that muscle-dependent trophic, cell adhesion, and axon-guidance signals play an essential role in the formation and maintenance of the neuromuscular junction. Therefore, muscle loss and damage (wasting) lead to various significant negative health consequences as in diabetes, cardiovascular disease and cancer cachexia. Cancer cachexia (CC) is a muscle wasting syndrome characterised by significant weight loss. Cancer cachectic patients experience numerous complications including, but not limited to, reduced effectiveness of chemotherapy, reduced mobility and reduced functionality of muscle-dependent systems, such as the respiratory and cardiovascular systems, leading to decreased quality of life and survival. More than half of cancer patients suffer from cachexia, and strikingly, nearly one-third of cancer deaths are related to cachexia rather than the tumour burden. Despite many decades of extensive animal studies, underlying mechanisms of cancer cachexia are still poorly defined and therapeutic options are limited. This is largely due to that animal models do not entirely reflect disease progression and complexity in humans. Furthermore, typical in vitro models of CC are generally established using animal derived cells and/or the use of skeletal muscle cell monolayer cultures, that fail to mimic in vivo conditions, particularly due to the lack of functional innervation/contraction. Thus, the development of new models to study and manipulate cancer cachexia has the potential to provide significant insight into mechanism underlying CC. In this study, we develop a novel in vitro co-culture model utilising human embryonic stem cells (hESCs)-derived motor neuron and immortalised human myoblasts to allow us to investigate cancer cachexia pathophysiology. This unique serum- and trophic factor-free co-culture provides a tool to study vital features of CC, will expand the understanding of the underlying mechanisms and will allow a more reliable evaluation of prospective chemotherapy drugs for translational purposes.