Stem cells out of the bag: Characterization of ex vivo expanded mesenchymal stromal cells for possible clinical use

Abstract

Aim: Mesenchymal stromal cells (MSC) are a promising tool for cellular therapy and regenerative medicine. One major difficulty in establishing a MSC expansion protocol is the large volume of bone marrow (BM) required. We studied whether cells trapped within a collection bag and filter system could be considered as a source of MSC. Results: From the 20 BM collection bag and filter systems, we recovered an average of 1.68 × 108 mononuclear cells, which is the equivalent to 60 ml of filtered BM. Mononuclear cells were expanded ex vivo to 17 × 106 MSC, with purity shown by a CD44+, CD105+, CD90+ and CD73+ immunophenotype, a reduction of 20% proliferating cells in a mixed lymphocyte reaction and also the ability of adipocyte differentiation. Conclusion: Long-term MSC cultures were established from the usually discarded BM collection bag and filter, maintaining an appropriate phenotype and function, being suitable for both investigation and clinical settings. Lay abstract Mesenchymal stromal cells (MSC) are a promising tool for cellular therapy and regenerative medicine. One major difficulty in obtaining MSC is the large volume of bone marrow (BM) required from a healthy donor. From usually discarded collection bags of BM collected for transplant, we recovered a number of cells equivalent to 60 ml of BM and expanded functional MSC with high purity. We believe that those recovered cells are an alternative to BM for obtaining MSC. The routinely recovery of such cells in reference centers, in a way similar to a public cord-blood bank, could benefit the scientific community, once further research is conducted to confirm results.