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PURPOSE OF THE STUDY In patients older than 40 years of age, treatment of chondral lesions of the knee employing microfractures does not provide satisfactory outcomes. One of the contributing factors may be the age-related lack of sufficient mesenchymal stromal cells able to efficiently migrate into the desired site of the lesion. Concomitant application of mononuclear cells (MNCs) or cultured mesenchymal stem cells (MSCs) isolated from bone marrow and seeded on a 3D scaffold could provide an alternative enhancing therapeutic efficacy in these patients. The aim of our study was to assess two different sources of bone marrow for isolation of progenitor cells. To be specific, material obtained from proximal tibia and iliac crest (the commonly used bone marrow source) was compared in terms of quantity and quality of cells and their suitability for cellbased treatment of chondral lesions. MATERIAL AND METHODS Bone marrow was collected during a total knee replacement surgery from the iliac crest and the proximal metaphysis of the tibia from ten volunteers older than 40 years of age, using aspiration biopsy needles. The MNCs from the obtained material were isolated, cultured and analyzed for their phenotypic features. Both sources were compared as to the yield and viability of MNCs and MSCs as well as the ability of MSCs of chondrogenic differentiation. RESULTS The MNCs concentration/yield was significantly higher in samples from the iliac crests. Similar results were obtained with cultured MSCs after the first passage when the MSCs/MNCs ratio was compared. Nevertheless, the qualitative analysis that included MSCs immuno-phenotyping, viability and population doubling time showed no difference between the two tested bone marrow sources. DISCUSSION Particularly in older patients, therapies of chondral defects employing bone marrow-stimulating techniques result in unsatisfactory outcomes. Therefore, orthopedic surgeons have turned their attention to cell-based treatments. Bone marrow located in pelvic bone and metaphysis of long bones (distal femur, proximal tibia) contains mononuclear cells that possess features of MSCs. In accordance with other authors, quantitative differences between the cells from two anatomical locations were found in our cohort of patients. Qualitatively, however, there was no significant variability observed. We also confirmed that the metaphysis of proximal tibia is a suitable source for cultured MSCs. Moreover, in contrast to several reports, the quality of these cells does not appear to decrease with the patients age. CONCLUSIONS The iliac crest represents a superior bone marrow source for the MNCs and MSCs yield when compared with tibia. However, there was no qualitative difference between the isolated and cultured cells. The population doubling time analysis showed that the tibia is a good alternative source of MSCs which can be obtained at therapeutically relevant numbers for example for the treatment of chondral lesions of the knee. Key words: bone marrow, mesenchymal stem cells, MSC, mononuclear cells, chondral defects, osteoarthritis. |
