The large cell doses (>1x10(6)cells/kg) used in clinical trials with mesenchymal stem/stromal cells (MSC) will require an efficient production process. Moreover, monitoring and control of MSC ex-vivo expansion is critical to provide a safe and reliable cell product. Bioprocess engineering approaches, such as bioreactor technology, offer the adequate tools to develop and optimize a cost-effective culture system for the rapid expansion of human MSC for cellular therapy. Herein, a xenogeneic (xeno)-free microcarrier-based culture system was successfully established for bone marrow (BM) MSC and adipose tissue-derived stem/stromal cell (ASC) cultivation using a 1L-scale controlled stirred-tank bioreactor, allowing the production of (1.1 +/- 0.1)x10(8) and (4.5 +/- 0.2)x10(7) cells for BM MSC and ASC, respectively, after 7 days. Additionally, the effect of different percent air saturation values (%Air(sat)) and feeding regime on the proliferation and metabolism of BM MSC was evaluated. No significant differences in cell growth and metabolic patterns were observed under 20% and 9%Air(sat). Also, the three different feeding regimes studied(i) 25% daily medium renewal, (ii) 25% medium renewal every 2 days, and (iii) fed-batch addition of concentrated nutrients and growth factors every 2 daysyielded similar cell numbers, and only slight metabolic differences were observed. Moreover, the immunophenotype (positive for CD73, CD90 and CD105 and negative for CD31, CD80 and HLA-DR) and multilineage differentiative potential of expanded cells were not affected upon bioreactor culture. These results demonstrated the feasibility of expanding human MSC from different sources in a clinically relevant expansion configuration in a controlled microcarrier-based stirred culture system under xeno-free conditions. The further optimization of this bioreactor culture system will represent a crucial step towards an efficient GMP-compliant clinical-scale MSC production system. Biotechnol. Bioeng. 2014;111: 1116-1127. (c) 2014 Wiley Periodicals, Inc.