Why Are In Vitro Models Important in Central Nervous System (CNS) Diseases?

CNS diseases are some of the leading causes of disability and are the fastest-growing neurological diseases in the world. It is hard to diagnose these kinds of diseases as the diagnoses primarily rely on symptoms like tremors and slowness, but these symptoms usually appear several years after the onset of these diseases. CNS diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD) are significantly more prevalent in the elderly. With an aging global population, the number of people affected by these degenerative neurological disorders is expected to rise to unprecedented levels.

AD is a complex, multi-factorial disease, and the age of onset, rate of progression, and development of pathology are highly variable between patients. Although there is currently no method to cure AD, experimental models are considered promising strategies for studying neural repair and neurological disease. However, there is no widely accepted animal model reproducing the full pathological profile of AD at present since the basic mechanisms of neurodegeneration are still poorly understood.

Recently, Alzheimer's disease in vitro models

• 3D cellular models have been well-acknowledged due to the provision of cues influencing cell structure, adhesion, proliferation, signaling, and mechanotransduction. Moreover, cells in 3D mimic the native target tissues in drug testing more accurately and allow the assessment of the effect of drugs in terms of the spatial features of the microenvironment of native tissue via microscopy.

PD affects approximately 2–3% of the population over the age of 65 and is characterized by the loss of dopaminergic neurons from the substantia nigra, leading to debilitating motor symptoms including bradykinesia, tremor, rigidity, and postural instability. There is no method to cure Parkinson's disease either, mainly attributed to the lack of understanding regarding the pathogenic process underlying dopaminergic degeneration.

Studies have demonstrated that a large amount of research data regarding PD pathophysiological mechanisms can be obtained using Parkinson's disease in vitro models, which can provide evidence and hypotheses about the initial steps of PD pathology and facilitate investigations of molecular cellular pathophysiological mechanisms of dopaminergic degeneration in PD and screening of potential therapeutics.

Overall, disease models, especially in vitro models, can help scientists understand the central nervous system disorders' pathogenesis and enable the testing of novel therapeutics. Certainly, considerable studies regarding the treatment of Alzheimer's disease and Parkinson's disease still need further exploration.