Introduction: Cigarette smoking is associated with musculoskeletal degenerative disorders and increased risk of fracture delayed- and non-union. A lower-than-average concentration of mesenchymal stem cells may be the reason for the reduced regenerative potential. The aim of this study was to compare the concentration of bone marrow MSC of smokers and non-smokers.

Methods: As part of a larger IRB approved clinical trial, 20ml bone marrow samples were processed and MSC were isolated. FACS analysis was used both to assess the purity of the separation process and to evaluate the number of MSC recovered from each sample. Differences in continuous outcomes between smoking and non-smoking groups were assessed by two tailed t test and difference between categorical outcomes was measured by chi square test.

Results: Twenty six subjects participated in the study. Thirteen were smokers and thirteen were non-smokers. Groups were not significantly different with regard to age and gender. The average concentration of MSC was 352.04x10³/ml for non smokers and 131.23x10³/ml for smokers (SD’s were 245.72 x10³/ml and 161.54 x10³/ ml respectively. The difference between the smokers and nonsmokers was significant (t=3.2 p=0.004).

Discussion: The present study indicates that cigarette smokers have lower-than-average concentration of MSC in their bone marrow. Since MSC are a key element in every regenerative process of the musculoskeletal system, our findings may contribute to understanding and prevention of delayed and non-union. Further investigation is undertaken to address the issue of bone marrow recovery after smoking cessation.