Treatment of chondral defects of the knee with one step matrix-assisted technique enhanced by autologous concentrated bone marrow: in vitro characterisation of mesenchymal stem cells from iliac crest and subchondral bone.

Cartilage repair is still an unsolved problem. In the last years many cell-based treatments have been proposed, in order to obtain good regeneration of cartilage defects. The Autologous Matrix-Induced Chondrogenesis technique (AMIC(®)) combines the micro-fracture procedure with the use of a specific biological membrane. The phenotypic feature of bone marrow cell population, harvested from iliac crest and knee subchondral bone of patients treated with the AMIC(®) technique, enhanced by autologous concentrated bone marrow, was analysed to evaluate potential variations of the cell population. Samples of eleven patients, with isolated chondral lesions grade III or IV were treated with the AMIC(®) technique, enhanced by the use of autologous concentrated bone marrow. A small fraction of bone marrow samples, both from iliac crest and from the created micro-fractures, was analysed by FACS analysis and then cultured to verify their proliferative and differentiation potential. An average of 0.04% of concentrated bone marrow cells harvested from the iliac crest, presented mesenchymal stem cell phenotype (CD34(-)/CD45(low)/CD271(high)), whereas just 0.02% of these cells were identified from the samples harvested during the creation of micro-fractures at the knee. After two passages in culture, cells expressed a peculiar profile for MSC. Only MSC from bone marrow could be long-term propagated and were able to efficiently differentiate in the cultures. Although the AMIC(®) approach has many advantages, the surgical technique in the application of the microfracture technique remains essential and affects the final result.