For instance, the priming of MSCs by proinflammatory cytokines may negatively affect the MHC class I and class II level; Hormones and/or growth factors may affect the differentiation capacity of MSCs; Priming by hypoxia may induce oxidative stress in MSCs; Growth factors may negatively affect the differentiation capacity of MSCs; Spheroid cultures owing to the variability in their size may lead to the necrotic spheroid core, thus, may interfere with the effectiveness of MSCs after transplantation.