Background

Yeast is a very useful microorganism employed in many fields such as medicine (e.g., aging related diseases), pharmaceuticals (e.g., drug screening), food (e.g., baking industry), beverage (e.g., brewing industry) as well as energy (e.g., biofuels). Yeast and more precisely Saccharomyces cerevisiae has been broadly used for modeling and investigating the molecular mechanisms underlying aging in eukaryotic cells. Aging also plays a crucial role in the performance of the cell in industrial production processes and thus, it is a powerful optimization parameter. However, cell age determination (more precise: the way in which a single cell ages) has hardly been considered as a strain engineering parameter so far and this is mainly attributed to the cumbersome and labor-intensive existing method. Yeast replicative lifespan (RLS) is determined by manual physical separation of the daughter cells from mother cell on a Petri dish employing a manual micromanipulator coupled with a microscope-mounted needle, followed by counting the number of divisions of the cell throughout its life. Typically, replicative lifespan of yeast strains ranges from 20-60 divisions, requiring 2-3 weeks for a single lifespan determination using the gold stand method, rendering it immensely expensive, tiresome, and thus not easily applicable, especially when high-throughput analysis is needed.

Technology Overview

The HAPPY team has invented an innovative microfluidic technology to track the replicative lifespan in yeast in a way that the workload is reduced by more than 92 %. The HAPPY method relies on a single-use device consisting of a hierarchical serial trapping system which traps virgin yeast cells (mother cells) as well as their offspring (daughter cells) in predefined locations. As the replicative lifespan of a yeast cell equals the number of its daughters, a subsequent counting of all trapped daughter cells reveals the age of the trapped mother cell. The HAPPY method does not require sophisticated visualization systems and/or software since it relies on a single snapshot of the channel where all the offspring are lined up followed by a simple cell enumeration. Thus, it will be applicable by researchers and strain developers worldwide. Setting-up the HAPPY method in their respective labs will allow them to perform fast and high-quality lifespan determinations with a great degree of control and experimental freedom.

Benefits

The proposed HAPPY method offers numerous advantages over the existing conventional gold standard method addressing replicative lifespan determination, namely microdissection. The main advantages over the existing method are the cost-effectiveness, the faster turnaround time, and the reduction of the workload. Moreover, the HAPPY method shares the advantages offered by the microfluidics technology such as, low power consumption, compactness/ portability, automation, and parallelization.

The idea to overcome the limitations of manual lifespan determination employing microfluidics is not innovative as such. Since 2012 a handful of microfluidic technologies have been developed that may be capable for substituting for this time- and labor-intensive existing RLS method. These approaches rely on clever geometrical structures to mechanically trap mother cells. While the mother cell is trapped, the offspring is flushed away and can be quantified based on a time-lapsed microscopic video after the experiment is over. Contrary to the aforementioned approaches, the HAPPY method differs due to the innovative hydrodynamic trapping mechanism employed in the HAPPY approach which is protected under a patent. In addition, another fundamental difference is the means of obtaining the RLS data, which unlike the other microfluid approaches, in the HAPPY method it relies solely on the use of a digital camera and the acquisition of a single snapshot through which the cells are counted, corresponding to the RLS determination.

Applications

Yeast lifespan determination in the fields of aging, drug screening, translational medicine, disease modeling, biofuel production, brewery industry, baking industry

Opportunity

UL is willing to partner with industrials to further validate the system