Cultivation in human serum reduces adipose tissue-derived mesenchymal stromal cell adhesion to laminin and endothelium and reduces capillary entrapment.

The increasing use of mesenchymal stromal cells (MSC) in clinical cellular therapy requires a safe and controlled production process compliant with Good Manufacturing Practice guidelines. Pooled blood group AB human serum (HS) has been used to replace fetal bovine serum (FBS), critically rated by the regulatory agencies, since it can support the expansion of adipose tissue-derived mesenchymal stromal cells (ASC). However, it remains unknown whether the choice of serum affects application-relevant characteristics of ASC. A microarray-based screen has revealed differentially expressed adhesion and extracellular matrix-associated molecules in HS- and FBS-ASC. Since cell therapy relies on the cells' efficacy to home and engraft, HS- and FBS-ASC were compared by analyzing adhesion, migration, and transmigration as well as short-term homing in vivo. HS-cultivated ASC demonstrated a higher adhesion to plastic, but reduced adhesion to extracellular matrix molecules, that is, laminin, and to endothelial cells both under static and flow conditions. Migration and transmigration assays confirmed the attraction of ASC by the tumor conditioned medium irrespective of the supplement. Coinjecting differently labeled HS- and FBS-ASC into nonobese diabetic, severe combined immunodeficiency mice revealed reduced numbers of HS-ASC in lungs and liver. This has been interpreted as reduced capillary entrapment. Our data indicate that varying the serum supplement may alter application-relevant characteristics of ASC, such as adhesion, as well as lung entrapment after infusion. Appropriate injury models and further molecular analyses are required to provide mechanistic insight into the differential effects of HS versus FBS on ASC cultures.