Aspirating bone marrow from the iliac crest using small volumes of 1-4 ml with a 10-ml syringe has been historically proposed for harvesting adult mesenchymal stem cells and described as a standard technique to avoid blood dilution. The disadvantage of repeated small aspirations is that there is a significantly increased time to harvest the bone marrow. However, it is not known if a large volume syringe can improve the rate of bone marrow aspiration without increasing blood dilution, thus reducing the quality of the aspirate. We compared the concentrations of mesenchymal stem cells obtained under normal conditions with two different size syringes. Thirty adults (16 men and 14 women with a mean age of 49 ± 14 years) underwent surgery with aspiration of bone marrow from their iliac crest. Bilateral aspirates were obtained from the iliac crest of the same patients with a 10-ml syringe and a 50-ml syringe. Cell analysis determined the frequencies of mesenchymal stem cells (as determined by the number of colonies) from each size of syringe. The cell count, progenitor cell concentration (colonies/ml marrow) and progenitor cell frequency (per million nucleated cells) were calculated. All bone marrow aspirates were harvested by the same surgeon. Aspirates of bone marrow demonstrated greater concentrations of mesenchymal stem cells with a 10-ml syringe compared with matched controls using a 50-ml syringe. Progenitor cell concentrations were on average 300 % higher using a 10-ml syringe than matched controls using a 50-ml syringe (p < 0.01). In normal human donors, bone marrow aspiration from 30 patients demonstrated a reduced mesenchymal stem cell number in aspirates obtained using a larger volume syringe (50 ml) as compared with a smaller volume syringe (10 ml).
