Cryo-hanging drops: Towards ready-to-use frozen biological samples for screening purposes in 96 well plate format

Since assays that are based on human cells, are becoming more and more precise and allow the reduction and refinement of animal testing, their application in drug screening and toxicity assessments is increasing. Decelerating factor for their use often is the lab-intensive routine work that has to be done beforehand and has to be scheduled precisely on demand according to the starting point. To overcome this costly and timeconsuming preparation steps, an application-ready product for screening purposes that can be stored over long periods is desirable. Therefore, we introduce here the Cryo - Hanging Drops (Cryo-HDs): Aliquoted droplets of cell suspension are frozen via equilibrium freezing on a die-casted, disposable plate that is compatible to 96 well plates. Upon application, it can be taken ready-To-use from a freezer and set on a prepared compound plate diluting the cell suspension drops into the desired media without additional washing steps.