High recovery of mesenchymal progenitor cells with non-density gradient separation of human bone marrow.

Background Aims: Bone marrow (BM) is the most used source of hemopoietic stem cells (HSC) and mesenchymal stromal cells (MSC) in both hematologic settings and regenerative medicine. We compared the feasibility and reproducibility of two gravity separation techniques, with or without the use of a density gradient, in terms of both hematopoietic and mesenchymal human BM progenitors.

Methods: A total of 16 BM samples was processed to obtain mononuclear cells (MNC) and buffy coats (BC). The efficiency of the two procedures was evaluated by recovery of white blood cells (WBC), MNC and CD34(+) cells, clonogenic assays, red blood cell (RBC) depletion, cell viability, expression of embryonic transcriptional regulators and MSC assessment.

Results: The two procedures yielded a comparable recovery of HSC. Non-density gradient separation (NDGS) of BM resulted in four times higher MSC recovery and higher expression of embryonic stem cell markers (Nanog and Sox2) compared with density-gradient separation (DGS). MSC derived from both procedures was comparable in terms of phenotype, differentiation and proliferation potential.

Conclusions: NDGS is less time consuming, provides a better MSC enrichment and appears to be a suitable cell preparation method for clinical applications.