Fabrication of Amyloid-β-Secreting Alginate Microbeads for Use in Modelling Alzheimer's Disease.

According to the amyloid cascade hypothesis, the earliest trigger in the development of Alzheimer's disease (AD) is the accumulation of toxic amyloid-β (Aβ) fragments, eventually leading to the classical features of the disease: amyloid plaques, neurofibrillary tangles and synaptic and neuronal loss. The lack of relevant non-transgenic preclinical models reflective of disease progression is one of the main factors hindering the discovery of effective drug treatments. To this end, we have developed a protocol for the fabrication of alginate microbeads containing amyloid-secreting cells useful for the study of the effects of chronic Aβ production. Chinese hamster ovary cells previously transfected with a human APP gene, secreting Aβ (i.e., 7PA2 cells), were used in this study. A three-dimensional (3D) in vitro model for the sustained release of Aβ was fabricated by encapsulation of 7PA2 cells in alginate. The process was optimized to target a bead diameter of 500-600 μm for further in vivo studies. Optimization of 7PA2 cell encapsulation in alginate was performed altering fabrication parameters, e.g., alginate concentration, gel flow rate, electrostatic potential, head vibration frequency, gelling solution. Levels of secreted Aβ were analyzed over time and compared between alginate beads and standard cell culture methods (up to 96 h). A concentration of 1.5 x 10