Coating strategies for expansion of mesenchymal stromal cells in a hollow-fibre bioreactor

Abstract

Background & Aim Background The increasing request for culture expanded mesenchymal stromal cells (MSC) in the last years discloses the need to reduce costs and man power in the manufacturing process. This can be achieved by the use of closed, (semi-)automated bioreactor systems. We have decided to test a functionally closed hollow-fibre bioreactor system (Quantum®). Surveillance of metabolic parameters and adaptation of feeding in dependence of these is possible. However, the nature of the hollow-fibre surface does not support attachment of MSC without coating. Several biological substances for coating are available, either as isolated proteins (e.g. fibronectin, vitronectin), or as complex protein mixtures derived from human blood (e.g. cryoprecipitate, platelet lysate). The use of such closed systems additionally reduces the risk of contaminations. Methods, Results & Conclusion Methods MSC were cultured as conventional cell culture or in a platelet lysate (PL), cryoprecipitate (CP), vitronectin (VN), or fibronectin (FN) coated Quantum® bioreactor (TerumoBCT) for 5 - 15 days in alphaMEM (Lonza), supplemented with 5% - 10% platelet lysate (PL from IKT Ulm) and 1 i.u. heparin (B.Braun). The surface of the Quantum® bioreactor is 21,000 cm2. For Quantum®, the feed rate was adjusted based on daily measured lactate or glucose levels. For conventional cell culture, mainly 2 chamber CellSTACK® (Corning) with a surface of 1272 cm2 were used and complete medium exchange was performed twice a week. TrypZEAN® (Lonza) was used for detachment of cells. Results For results of the cell expansion experiments (N ≥ 3) using the different coating reagents refer to Table 1. Conclusion We showed that the Quantum® bioreactor is suitable for expansion of MSC using PL, CP, FN or VN as coating reagent. Despite higher doubling times for cells grown in the Quantum®, this system may help to save costs since less man power is needed to manage the system and several steps do not necessarily have to be performed in a class A cabinet. In addition, clinically relevant cell numbers could be achieved by the use of a single bioreactor (data not shown). Perspective Protocols for cell expansion in the Quantum® still may have to be optimized in order to increase its potential in saving man power and consumables.