Stem cell therapy is considered a promising approach against previously incurable diseases such as Type 1 diabetes or Parkinson’s disease. However, to use them widely, large quantities of high-quality stem cells are needed – a major obstacle until now.

Limitations of conventional bioreactors

In conventional stirred-tank bioreactors with a volume of up to approximately 2 litres, the oxygen supply is provided via the headspace above the culture medium (nutrient solution). For larger volumes (from 2–10 L), oxygen must be introduced into the medium as a gas. The resulting bubbles can damage or destroy the sensitive stem cells through mechanical shear forces as they rise or burst. This limits safe cultivation to small reactors – with manufacturing costs of up to one million US dollars per dose.

The KISSEN solution: bubble-free membrane stirrer

The KISSEN project addresses exactly this: a novel “membrane stirrer” enables gas exchange without bubbles. Dense but gas-permeable membranes are attached to a rotating stirrer for this purpose. In this way, the medium is gently mixed and the cells are efficiently supplied with oxygen – without harmful bubble formation. Measurements show a six- to ten-fold higher oxygen transfer into the medium compared to the conventional reactor type.

The approach is scalable: the membrane surface area available for gas exchange grows proportionally with the reactor volume. The initial goal is successful use in a reactor volume of at least 10 litres, prospectively up to 50 litres. At the same time, foaming is avoided, meaning that additional space no longer needs to be kept free in the headspace of the reactor. This significantly increases the filling volume and productivity.

KISSEN thus paves the way for the cost-effective, large-scale production of stem cells – and brings future cell therapies closer to providing care for many patients.

More on funded GO-Bio projects on the overview page