Mesenchymal stem/stromal cells originate from the embryonic mesoderm layer, from which cartilage, bone, muscle, fat, and other connective tissues develop during embryonic development. They are located in anatomically specific areas called niches. The niche is the cellular microenvironment that provides the support and stimulation necessary to maintain self-renewal potential. Due to their immunosuppressive action, mesenchymal stem/stromal cells are used to treat severe forms of graft-versus-host disease, deep cartilage lesions, osteoarthritis, and some autoimmune diseases. Mesenchymal stem/stromal cells are easily accessible as they can be isolated from any adult connective tissue, have the ability to adhere to plastic surfaces, form colonies and are multipotent. Isolated mesenchymal stem/stromal cells represent a very heterogeneous population, so identification criteria must be followed to properly identify the mesenchymal stem/stromal cells.
Tissues from post mortem donors are an important subject of research as they represent a potential source of various mesenchymal stem/stromal cells that can be isolated up to 17 days after death. As so, the use of mesenchymal stem/stromal cells isolated from these tissues would reduce the need for foetal or embryonic stem cell sources, thus avoiding ethnical issues associated with the use of these tissues.
The aim of our thesis was to determine the immunophenotype of mesenchymal stem/stromal cells isolated from different knee (synovial membrane) and the peri-knee tissues (bone and periosteum). Primary cells, previously isolated from all these tissues, presented the samples used in our study. In vitro cultured mesenchymal stem/stromal cells were immunophenotyped by flow cytometry using antibodies directed against the surface markers (CD45, CD14, CD19, CD73, CD90 and CD105). Our results are indicating that knee (synovial membrane) and peri-knee (bone and periosteum) tissues from post mortem donors represent a valuable source of primary cells with mesenchymal stem/stromal cells -like immunophenotype. Our results demonstrate that there are no differences in the expression of positive and negative mesenchymal stem/stromal cells markers between the three tissues, suggesting that the synovial membrane and the periosteum have a great potential as tissue sources for mesenchymal stem/stromal cells isolation. However, the vast majority of our isolated cells do not meet the identification criteria.
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