Flow Cytometry-Research & Regenerative Medicine Department, IASO- Maternity & Research Hospital, Greece
Submission: October 05, 2016; Published: October 14, 2016
*Corresponding author: Vasiliki E Kalodimou, Director at Flow Cytometry-Research & Regenerative Medicine Department, IASO- Maternity & Research Hospital, Athens, Greece, India, Tel:+302106185203,+306974446030,+306956205250; Email;email@example.com
In the field of regenerative medicine, basic research and preclinical studies have been conducted to overcome clinical shortcomings with the use of stem cells, mesenchymal stem cells and adipose stem cells. They are present in adult tissues, including bone marrow, umbilical cord, umbilical cord blood and adipose tissue . For many years, bone marrow-derived stem cells were the primary source of stem cells for tissue engineering applications. Russian-born Alexander A. Maximow in 1924 used extensive histological findings to identify a kind of spherical precursor cell in the mesenchyme, which can grow and differentiate into Different cell types. In late 1960’s the scientists Ernest A. McCulloch and James E. Till reveal for the first time the clonal nature of bone marrow cells . The challenge was to find those cells that can self-renew and differentiate into three cell types: bone, cartilage and fat (Figure 1).
The adipogenic differentiation is usually defined by the appearance of cells containing intracellular lipid droplets. Both AT-MSC (ASC) and UC-MSC have been successfully differentiated into adipocytes. The chondrogenic differentiation capacity of MSC is evidenced by the formation of shiny cell-spheres expressing type II collagen in pellet cultures. Enhanced alkaline phosphatase expression and mineralization assayed by von Kossa or alizarin red staining indicates the occurrence of osteogenic differentiation [1,2].
The human mesenchymal stem cells (hMSC’s) are typically isolated from the mononuclear layer of bone marrow after separation by centrifugation. The mononuclear cells were cultured in medium with 10% fetal calf serum, and adhere to the walls.
Some of the hematopoietic cells adhere well, but over time in culture they are lost. Mesenchymal stem cells are characterized morphologically by a small cell body. The cell body containing a large, round nucleus surrounded by fine particles of chromatin in the nucleus, allowing clarity. The remain of the cell body containing a small amount of Golgi, mitochondria and polyribosome’s (Figure 2) [2,4]. Mesenchymal stem cells (MSC’s) are characterized by great “plasticity”, i.e., have the ability to differentiate to form various cell types. For this reason it can be used in regenerative medicine to regenerate tissues and organs. Another important characteristic of the mesenchymal stem cell proliferation is the ability of these cells, to proliferate without losing their “plasticity”[2,3].
Beyond that, there is little we can say with confidence. Numerous studies have shown that human MSC’s avoid self- recognition and interfere with the dendritic cells and T-cells and create an immunosuppressive microenvironment of the cytokines they secrete [5,6]. Other studies contradict some of these findings, reflecting the highly heterogeneous nature of MSC isolated and significant differences between the isolated cells are created by many different methods under development. The majority of modern techniques still use the approach CFU, wherein the bone marrow with or without ficoll spreads directly into cell culture plates or flasks. The mesenchymal stem cells, but not the red or hematopoietic cells adhere to the plastic medium within 24 to 48 hours. [7-9].
The major sources of human mesenchymal stem cells
(MSC) can be distinguished between adult tissues, preferably
bone marrow (BM), peripheral blood (PB) and adipose tissue
(AT) and neonatal birth-associated tissues, including placenta
(PL), umbilical cord (UC) and cord blood (CB) [1,2]. With
flow cytometry sorting we marrow cells to specific surface
markers, such as STRO -1, STRO-1 + cells, which are generally
more uniform, and have higher capacity and higher rates of
proliferation, differentiation, but the exact differences between
STRO-1 + cells and MSC’s they are not clear yet [1,10,11]. The ISCT
(International Society of Cellular therapy), has proposed a set of
standards for determining the MSC. A cell can be characterized
as MSC’s if displays plasticity under normal culture conditions
and has a fibroblast-like morphology.
Moreover, it can be differentiated ex-vivo in bone, fat and
cartilage. Phenotypically express a number of indicators, none of
which is specific to the MSC’s. It is generally accepted that adult
human MSC’s do not express hematopoietic markers (Cells must
show <2% positivity for the expression of cell-surface antigens,
Negative markers): CD45, CD34, CD14, CD11, CD80, CD86, CD40,
CD31, CD18, or CD56, but do express (Cells must show >95%
positivity for the expression of cell-surface antigens, Positive
markers): CD105, CD73, CD44, CD90, CD71, CD106, CD166 and
CD29 (Table 1 & 2). The cultured MSCs also expresses on their
surface markers such as CD73, CD90 and CD105, while lacking
the expression of CD11, CD14, CD19, CD34, CD45, CD79 and