However, we noted a trend in reduction in spine density following B103-CM treatment alone. At lower dilutions of conditioned medium, i.e. more concentrated, the cultured neurons were distinctly unhealthy (data not shown). Therefore, the degree of rescue in the sAPPα-B103 medium may have been artefactually depressed due to the experimental paradigm of using B103 cells. Nonetheless, the results strongly suggested that lack of sAPPα is a major factor accounting for spine loss in APP−/− neurons.
