Microfluidic chips in obesity research: A review on natural products and invertebrate models for obesity management.

The annual economic burden of obesity has reached 190 billion dollars in the US and around 62 billion Egyptian pounds in Egypt. It is linked to many harmful diseases, including diabetes mellitus, cardiovascular, liver, reproductive, bone diseases, and many others. Modeling of obesity and obesity-associated comorbidities represents a fruitful area of research. Animal models of obesity have many limitations regarding reliability, translatability, and extrapolation to human obesity. Microfluidic "organ on a chip" has emerged in recent decades as a potent in vitro tool for studying human diseases, offering advantages over traditional in vitro models, thereby facilitating the development of a human on a chip model. This review will briefly discuss obesity-associated metabolic disturbances and the recent publications that tried to use microfluidic devices to answer obesity-related questions. This review covers the role of in vitro modeling using microfluidic devices in obesity research. The different species of invertebrates utilized in obesity research have also been investigated, including nematodes, with a highlight on Caenorhabditis elegans. Research on anti-obesity drugs, which could potentially aid in managing obesity, has been increasing daily. Natural anti-obesity phytoconstituents have shown considerable therapeutic potential in obesity, with many plant extracts and single components with promising effects. In conclusion, integrating microfluidics, invertebrate models, and phytochemical screening is promising for obesity research, yet it requires further standardisation and clinical validation to enable personalised therapies.