A researcher from China has been looking for an in vitro platform to run cancer cell migration assays. He found that AIM 3D Cell Culture Chips are suitable for his application as the chips offer useful features such as the ability to monitor live cell migration. However, he faced a problem in filling medium into the media channels without leakage, after filling the gel channel with Matrigel. After a discussion, we realized that the underlying reason could be the concentration of the Matrigel that was used. We advised him to use Matrigel without dilution, and to try another batch of Matrigel if the first option fails. In the end, he successfully solved this problem by using a higher concentration of Matrigel and by controlling injection pressure during the gel filling step.
The researcher is interested in using AIM chips for cell migration assays where cancer cells seeded into the media channels can be observed invading into Matrigel. He likes the fact that he can observe and quantify the cell migration process without any ambiguity. However, after filling the gel channel with Matrigel, 50% of the AIM chips failed when he injected medium into media channels. He noticed that medium would leak from one media channel into another channel. In some cases, the medium would pass through the Matrigel and leak out from gel inlets. This could indicate gel disruption. In addition, bubbles were trapped inside the Matrigel during gel filling. This problem still occurred occasionally, even though he was careful to make sure the Matrigel solution was bubble-free.
The researcher had diluted the Matrigel with medium in a 1:1 ratio to a concentration of 4 -8 mg/ml. Based on feedback from other users who use Matrigel to construct 3D matrixes, Matrigel should be used undiluted and preferably in the range of 10 -12 mg/ml. The researcher further confirmed that he was able to prevent the leakage of medium by increasing the concentration of Matrigel. Besides, he also found that a slower gel filling rate* would help to solve this problem too.
In the discussion with the researcher, we also realized that he did not change the pipette tip between each gel filling step as he was concerned that Matrigel would polymerize quickly if he did not complete the filling process as soon as he could. Due to the high viscosity of Matrigel, there is usually some leftover gel in the pipette tip after every gel filling step. This will create air bubbles in the subsequent gel filling step if the same pipette tip is reused. Therefore, we recommend using a fresh pipette tip to fill each new gel channel.
*Fast or slow is a subjective term, you may need to optimize the filling step for your application. Matrigel may polymerize and block the gel channel during the gel filling step if the filling process is too slow.
Matrigel can be tricky to work with as it is viscous and it polymerizes very quickly at room temperature (you may find this article helpful in handling Matrigel). For the application of Matrigel in AIM chips, we recommend using Matrigel undiluted and preferably within the range of 10 -12 mg/ml. Gel filling rate should be optimized for your application. We recommend using a fresh pipette tip to fill each new gel channel to prevent bubbles from being trapped within the channel.