Joint Preservation Blog

February 12, 2009

Bone Marrow Nucleated Cell Concentrate (BMAC): Is it Concentrated Enough?

 

bmac machine

bmac machine

 

In 2005-2006 we mixed up BMAC in our cell biology lab.  It was easy to create from a marrow aspirate.  We performed some basic MRI studies with pre and post 3.0T high field studies and ran outcome questionnaires for knee and hip arthritis patients.  We were unimpressed by the results and because of this experience moved on to culture expanded mesenchymal stem cells.  

 

BMAC has become popular of late. In this procedure, a physician takes a bone marrow aspirate, places it in a specially designed centrifuge and pulls out a concentrate of bone marrow nucleated cells. This has been billed as a stem cell concentrate, but the stem cells that are concentrated in reasonable numbers tend to be CD34+ heme progenitors (stem cells that make new blood) and not MSC’s (Mesenchymal Stem Cells). Since MSC’s are the MVP of the adult stem cell mix available in a bone marrow concentrate, their concentration is very important to the success of such a treatment. A recent study on bedside bone marrow concentrate machines for MSC’s (BMAC) determined what concentrations were possible from a commercially available centrifuge unit. Using this study to calculate MSC numbers, a 60 ml bone marrow draw would produce 70,000-90,000 MSC’s. The Regenexx procedure yields after culture expansion are in the 5M-100M range. Based on this data, the Regenexx procedure produces approximately 100-1,000 times more cells than you can obtain with BMAC bedside systems. Based on this and other data, our best estimate is that the average micro fracture procedure would release 5-10 ml of un-concentrated marrow, so about 500-1,000 MSC’s into the defect site. Our own dosing data and the copious animal research would suggest that for appropriate cartilage, tendon, ligament, muscle repair the necessary MSC dose is in the millions range. Obtaining that amount of MSC’s from a BMAC system would require unacceptably high volumes of whole marrow from the patient. The conclusion, while very convienent, BMAC doesn’t have the right stuff.

For more information on different stem cell types, I’ve posted a video below:

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