#155 Bone Marrow Aspirate from the Vertebral Body: The Effect of Temperature, Media, and Time on Nucleated Cell Survival

General Session: What's New in Biologics and Biomechanics

Presented by: M. Webb

Author(s):

M.L. Webb (1)
R. Badrinath (1)
J.W. Hustedt (1)
J.N. Grauer (1)

(1) Yale Department of Orthopaedics and Rehabilitation, New Haven, CT, USA

Abstract

Introduction: Bone marrow aspirate (BMA)from the iliac crest and the vertebral body have been shown to promote spinal fusion. The nucleated cell count (cells/ml) of BMA has been associated with this positive effect. Nucleated cell counts have been shown to be proportional to alkaline phosphatase producing cells (osteogenic cells) in prior studies. Factors such as aspiration volume, age, and gender have been associated with nucleated cell counts in BMA.

This study was performed to evaluate the potential effect of controllable factors to optimize survival of cells in BMA once it has been harvested. Time since aspiration, storage temperature, and storage media were evaluated.

Methods: Using a cannulated pedicle tap,4 mlof vertebral BMA were obtained from left and right adult lumbar pedicles during instrumentation for degenerative or deformity issues. Using a hemocytometer, nucleated cell countswere determined from aliquots of these specimens. For aliquots from the right pedicles, cell counts were performed at times zero, 0.5 hours, 1 hour, 2 hours, and 4 hours after aspiration when left at20°C. For aliquots from the left pedicles, cell counts were repeated after one hour of storage at0°, 20°, or 37° C, as well as after one hour in alpha minimal essential medium (aMEM), saline, or no medium at 20°C.

Results: Preliminary data has been collected on 28 pedicles and the following cell counts are expressed as106 cells/ml.

With time, nucleated cell counts decrease: at time zero 5.36 ±0.76, at 0.5 hours 3.59±0.57,at one hour 3.34±0.54, at 2 hours 2.91±0.64,and at 4 hours 2.48±0.37. Cell counts had decreased by approximately half at 2 hours post aspiration.

These initial data show no trend or statistical difference between nucleated cell counts after one hour at 0°, 20°, or 37° C (4.95 ± 1.83, 5.16±1.04, and 37° 6.26± 1.18, respectively).These data also show no trend or statistical difference between nucleated cell counts after one hour in saline, aMEM, or in no medium (5.23± 0.81, 5.22± 1.27, 4.64 ± 1.00, respectively).

Discussion and Conclusion: The vertebral body is a readily available source of BMA in spinal instrumentation cases. We expected that handling conditions of the BMA prior to implantation might significantly affect cell viability. Preliminary data suggest that BMA cell counts slowly decrease with increasing time from aspiration (decrease by approximately half by two hours),but that choice of temperature and medium for storage of vertebral BMAdoes not significantly affect nucleated cell counts.