2025 ISAKOS Biennial Congress ePoster
There Is Significant Patient To Patient Variation In M1:M2 Macrophage Sub-Populations In Concentrated Bone Marrow Aspirate: A Prospective Review
James J. Butler, MB, BCh, New York, New York UNITED STATES
John F Dankert, MD, PhD, New York, NY UNITED STATES
Mohammad T Azam, BS UNITED STATES
Jari Dahmen, MD, BSc, Amsterdam NETHERLANDS
Sebastian Krebsbach, BS, New York UNITED STATES
John G. Kennedy, MD, MCh, MMSc, FFSEM, FRCS (Orth), New York UNITED STATES
NYU Langone Health, New York, NY, UNITED STATES
FDA Status Not Applicable
Summary
This prospective study revealed substantial patient-to-patient variation in the M1:M2 macrophage ratio within concentrated bone marrow aspirate, suggesting that a more favorable anti-inflammatory ratio might be associated with better clinical outcomes, though further research is needed to establish this link.
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Abstract
Introduction
Concentrated Bone Marrow Aspirate (cBMA) is a biological adjuvant that is widely utilized in orthopedic surgical procedures. There is a paucity of data regarding the composition of the monocyte population within cBMA, especially the M1:M2 macrophage sub-population. It is plausible that patients with a "favorable" anti-inflammatory M1:M2 macrophage sub-population (lower ratio) would have superior outcomes compared to patients with a more pro-inflammatory M1:M2 macrophage sub-population. The purpose of this prospective study was to characterise the various cellular populations in cBMA, with an emphasis on the monocyte sub-populations. In addition, we sought to determine the M1:M2 Macrophage ratio within cBMA, which has not been described to date.
Methods
The study proposal was reviewed and approved by an Institutional Review Board. Patients aged 18-85 years old undergoing a foot and ankle procedure with cBMA injection were offered enrolment into this study. Patients with a history of inflammatory disorders, corticosteroid use, cancer, and previous injections in the past year were excluded. Samples of peripheral blood (PB), bone marrow aspirate (BMA), and cBMA were collected during the procedure. The samples were analyzed by automated cell counting and multicolor fluorescence activated cell sorting with specific antibodies recognizing monocytes (CD14+CD16+) and the M1 (CD86+) and M2 (CD163+CD206+) populations within that monocyte population. Cytokine concentrations within the samples were evaluated with ELISA.
Results
Thirty-eight patients with a mean age of 45.2 ± 15.8 years. There was a statistically significant higher white cell count, monocytes, lymphocytes, neutrophils and platelets in the cBMA cohort compared to the BMA and PB cohorts (p< 0.0001). The mean classical monocyte population was 78.3%, 76.5% and 75.1% for the cBMA, BMA and PB cohorts, respectively. The mean non-classical monocyte population was 10.4%, 8.5% and 12.1% for the cBMA, BMA and PB cohorts, respectively. The mean M1:M2 ratio was 90:6, 90:6 and 90:8 for the cBMA, BMA and PB cohorts, respectively. There was significant patient to patient variation in the M1:M2 ratio across the cBMA, BMA and PB cohorts.
Discussion And Conclusion
This prospective study demonstrated that the M1:M2 ratio in cBMA varied significantly from patient to patient. This suggests that patients with a "favorable" anti-inflammatory M1:M2 monocyte population would likely have superior clinical outcomes in comparison to patients with a more pro-inflammatory M1:M2 monocyte population. Further clinical studies are warranted to correlate the M1:M2 ratio to clinical outcomes.