Resumen de Bioengineering of brain organoids
Understanding the human brain is an exciting challenge in particular for scientists. Studying the behavior of the human brain can lead to understanding the causes of several diseases and delineate a path to find possible cures. The use of animal models has helped scientist historically to meet these goals; however, there are important differences between humans and animal models. Particularly on the field of neuroscience, these differences lead to a poor translation into clinics. To overcome this problem, scientists have recently developed brain organoids; an in vitro model of the brain made out from human cells. Brain organoids are generated from human stem cells (embryonic (hESCs) or induced (hiPSCs)), therefore recapitulate some aspects of human brain development and the mature brain. However, the model has some limitations, so it needs to be optimized to reach its full potential. Some cell types are underrepresented or even absent in the organoids compared to the brain. Endothelial cells, for example are missing, therefore organoids have a lack of vasculature that results on the generation of a necrotic core in the center of the organoids. Additionally, organoids are heterogeneous and rather immature compared to neural tissue. In this doctoral thesis, we evaluate several approaches to resemble better the in vivo setting and optimize brain organoid generation. First, we use physiological [O2] instead of atmospheric [O2] (commonly used in cell culture). As a result, we observe an increased neuralization on brain organoids. Second, we study the effect of electrical stimulation (ES) during brain organoid generation. By stimulating during neural expansion phase, we observe a reduction on the necrotic core size in mature organoids. Third, we evaluated the effect of ES using brain organoids grown on conductive scaffolds, and we detect an increased maturation rate on stimulated brain organoids grown on pyrolyzed carbon scaffolds. Additionally, we identify an altered pattern of neuronal formation on organoids grown on such scaffolds. We also show preliminary results of 3D bioprinting and microfluidics, applied to brain organoid generation. Using these approaches, we optimized brain organoid generation in terms of improved neuralization, increased maturation and reduced necrotic core. Therefore, we found several ways to alleviate limitations of current brain organoids
