Bone marrow obtained by iliac crest aspiration is a common source for harvesting mesenchymal stem cells, other progenitor cells, and associated cytokine/ growth factors. Because the use of bone marrow aspirate concentrate (BMAC) is currently approved by the United States Food and Drug Administration, it represents one of the few means for acquiring progenitor cells and growth factors for subsequent injection.
After density gradient centrifugation to remove red blood cells, granulocytes, immature myeloid precursors, and platelets, progenitor cells account for a small population within the bone marrow (0.001% to 0.01%). However, a high concentration of growth factors, including platelet-derived growth factor, transforming growth factor-b, and bone morphogenetic proteins 2 and 7, which are reported to have anabolic and anti- inflammatory effects,8-10 are present in BMAC. Of note, it has been reported that BMAC has a considerable concentration of interleukin-1 receptor antagonist (IL-1RA). This molecule inhibits IL-1 catabolism and therefore may be responsible for the beneficial symptomatic pain relief with this biologic approach.
A recent systematic review reported good to excellent outcomes with the use of BMAC for the treatment of focal chondral defects and mild to moderate osteoarthritis (OA) of the knee with a relatively safe profile. However, harvesting and processing techniques are vital to achieve optimal molecular concentrations and of both stem cells and growth factors in order to ultimately achieve satisfactory results. The purpose of this Technical Note was to describe the bone marrow aspiration technique and processing method.