Mesenchymal stem cells are easily isolated from bone marrow and other body tissues, such as adipose, umbilical cord, and peripheral blood. All mesenchymal stem cells have a multipotent differentiation capacity into a variety of cell types, like osteoblasts, chondrocytes, adipocytes, and myoblasts.
Human circulating mesenchymal stem cells, also called human peripheral blood mesenchymal stem cells, were initially discovered as fibroblast-like cells. Usually, these cells exist in less population in healthy individuals, but under pathological conditions, circulating peripheral blood mesenchymal stem cells are increased.
Biological characteristics of Human peripheral blood mesenchymal stem cells
Circulating mesenchymal stem cells or peripheral blood mesenchymal stem cells also fulfill the characteristics that have been defined by the International Society for Cellular Therapy for categorizing progenitor cells like mesenchymal stem cells: (1) plastic adherence (2) expression of specific surface antigen and (3) multipotent differentiation potential.
Compared with bone marrow mesenchymal stem cells, the frequency of peripheral blood mesenchymal stem cells is even lower. In a 2000 research paper, Zvaifler and co-workers successfully identified mesenchymal precursor cells and referred to them as blood mesenchymal precursor cells. These cells were positive for vimentin, collagen I, BMPR IA and IB, but did not express CD34, CD45, and CD14. From mobilized peripheral blood cells, fibroblast-like cells were reported by Zvaifler et al. Although a bit difficult to detect, peripheral blood mesenchymal stem cells have been found in various species, such as guinea pig, rabbit, mouse, rat, and humans. Bone marrow-derived mesenchymal stem cells and peripheral blood mesenchymal stem cells show similar characteristics of cell proliferation and differentiation potentials. With more research, scientists have reported CD73 to be an important indicator for distinguishing blood-derived and peripheral blood mesenchymal stem cells. Peripheral blood mesenchymal stem cells can be differentiated into adipocytes, chondrocytes, and osteocytes under specific conditions.
How to get circulating mesenchymal stem cells?
Although bone marrow-derived mesenchymal stem cells can be isolated and cultured easily, isolating circulating or peripheral blood mesenchymal stem cells is complicated. Compared to bone marrow-derived mesenchymal stem cells, the count of peripheral blood mesenchymal stem cells is rarer in blood. The general method to isolate these cells is Ficoll-Paque. The number of these cells can be significantly increased in case of various cytokine release due to injured tissues, although the related pathways have not yet been elucidated clearly. In some recent studies, administration of some cytokines like G-CSF has reported mesenchymal stem cell mobilization, forming peripheral blood mesenchymal stem cells. Kassis et al. have isolated peripheral blood mesenchymal stem cells using fibrin microbeads with G-CSF treated donors. Whereas Iwasaki et al. reported that the hepatocyte growth factor to be a stimulant for mobilizing circulating mesenchymal stem cells.
Applications of mesenchymal stem cells
Most of the clinical studies on orthopedic, cardiac, and other disorders are conducted using bone marrow-derived, adipose-derived, and umbilical cord-derived mesenchymal stem cells but peripheral blood mesenchymal stem cells application is rarely reported. Some research studies demonstrated that peripheral blood mesenchymal stem cells could enhance bone regeneration in critical bone defect models.
Although mesenchymal stem cells have garnered promise against a broad spectrum of diseases including neuro disorders, orthodisorders, anti-aging, etc., the understanding and efficacy need improvement in the clinical translation scenario. For more information on the role of mesenchymal stem cells or if your lab is working on mesenchymal stem cells, contact email@example.com