Amazing conversation! It stimulated this pipe dream in me:<br><br>Can an organoid be coaxed into integrating into a living brain?<br><br>Can an organoid be grown on a neural interface scaffold, such that rudimentary interfacing starts in-vitro?<br><br>If a yes can be found for those two questions, can a high bandwidth BMI be grown in-vitro from host stem cells  and then implanted?,(reply>), All great questions!<br>The simple answer to first two is 'Yes', BUT: (1) although organoids can be transplanted into the living brain and they form connections with surrounding structures, there are challenges to fine tune balance between number of cells vs safety of transplant; and (2) current in-vitro systems allow organoid growing on a multi-electrode array (MEA) system to read out information from it about electrical signals between neurons but programming of these signals is non existent for now - just simple stimulation of neurons is possible but not a complex encoding of a certain function for a neuronal circuit. But like Paola said the field is still very young! And high bandwidth BMI is more complex than MEA and offers more possibilities.<br>For now though, when it comes to anything that is to be transplanted into the brain, with current knowledge of protocols to guide stem cells into neurons, it is safer to deal with a 2D neuronal cell culture than 3D organoids to reduce the number of undifferentiated cells and minimize risk of transplant overgrowth (this in fact is currently true for most types of cells not just neurons investigated in the context of cell therapy).<br>I hope this helps! :)