| Stem cell research has always been a hot spot in life science since it had been discovered. In 2000, Stem Cell was listed as the first of the 10 most important research fields of the 21st century by Science. Stem cells are a class of cells which have the potential to renew themselves and differentiate into one kind of mature cells at least.The basic function of stem cells is responsible for updating the normal physiological aging or dead cells,involved in regeneration and repair damaged tissue.From the development characteristics of stem cells, one of the important characteristics of stem cells is that they have high degree self-replication capability. This suggests that at different developmental stages,stem cell lines may be remained in adult tissues, including embryonic stem cell lines.As lack of definite marker in the surface of stem cells,it is difficult to purify a single cloned stem cells for population study. This has limited our understanding of stem cells.It has been confirmed that stem cells exist in many kinds of adult tissues. These stem cells derived from adult tissue have been called adult stem cells,and they have the ability of self-renewal and differentiation into all kinds of cells origined from. In recent years, multipotent stem cells from several adult tissues have been identified and have shown that they can differentiated into multi-mesodermal tissue cells.The result indicates that early embryo-like stem cells may be retained in adult tissues. In Conrad's study in 2008, spermatogonial stem cells extracted from human testes had all the features of embryonic stem cells, which approved that stem cells during embryonic development exist in adult reproductive organs.Bone marrow is one of the important human organs, which has a variety of adult stem cells. Usually,bone marrow-derived stem cells can be divided into hematopoietic stem cells and non-hematopoietic stem cells. In previous studies, the researchers believed that the main role of the non-hematopoietic stem cells is to support the growth and development of hematopoietic stem cells. With the in-depth study, it was discovered that bone marrow non-hematopoietic stem cells have broad differentiation potential and can differentiate into a variety of other tissue-derived cells. Therefore, embryonic-like stem cell population may exist in the bone marrow non-hematopoietic stem cells.In the first part of this study, We used bioinformatics techniques, through the Internet in the United States National Library database(NCBI), DDD (Digital Differential Display) analysis, obtained results showed that Granzyme B(GRB)is the greatest difference in gene expression products between adult cells and embryonic 8-cell stage. Then we reviewed the previous study on the embryonic stem cell research,and drawed the conclusion that SSEA-1(Stage specific embronicantigen-1)and OCT-4 (Octamer-4)proteins are two key proteins in embryonic stem cells. Finally, we determine to observe whether the cell subsets expressed these three proteins existed in adult stem cells.In the second part of the study, We isolated C57 mouse bone marrow-derived adult stem cells, discarded suspended hematopoietic stem cells ,and obtained adhesive bone marrow-derived stem cells(BMSCs). These cells were confirmed that they were stem cells with multipotent differentiation capacity. Then preparation of stem cells attached coverslips, SSEA-1,GRB and OCT-4 were detected by immunofluorescence staining.The result showed that some cell subsets in bone marrow-derived adult stem cells expressed these proteins.It indicated that embryonic-like stem cells subsets may exists in bone marrow. In order to further observe whether these markers exist in other tissue-derived adult stem cells,we isolated C57 mouse adipose-derived stem cells(ADSCs),and confirmed they had the same ability of multipotent differentiation as the stem cells derived from bone marrow. Using the same immunofluorescence staining method,we found these proteins were expressed in ADSCs.This conclusion suggests that embryonic-like stem cells subsets may also exists in adipose tissues.In this part study,we also observed the difference of characteristics in growth and induced-differentiation between BMSCs and ADSCs. In the same conditions of cell isolation and culture used in the experiment, BMSCs were more difficult to obtain and culture than ADSCs. It had lower probability of success in culture of BMSCs than that of ADSCs.The proliferation of BMSCs were slowly than that of ADSCs in the early culture stage. After culturing to the fifth generation, the proliferation rate of BMSCs was close to that of ADSCs.By different way of organizations separation, we obtained dermal-derived stem cells with multipotent differentiation potential from the skin. Using the same staining method, we confirmed that the dermal-derived stem cells could also express these three kinds of markers mentioned above.It indicated that the skin may also exists embryonic-like stem cell subsets.As the SSEA-1 was expressed on the surface of part cells in BMSCs in the previous study,we utilized immunomagnetic beads to purify BMSCs,and got a group of cells expressed SSEA-1 positive. In vitro, SSEA+-BMSCs could be induced differentiation into adipose-like cells,neuron-like cells and islet-like cells.These results indicate that SSEA+-BMSCs take some characteristics of embryonic stem cells and may be embryonic-like stem cells which remain in the adult tissues during embryonic development.Bone marrow, as one of the vital organs of the body, contains a large number of adult stem cells. To study the rules and mechanisms of BMSCs in trauma healing would enhance the effect of trauma treatment. In the fourth part of this study, C57 female mice were transplanted with the third passage of BMSCs marked with 5-Bromo-2′-deoxyuridine(Brdu) through the tail vein after 5Gy irradiation. Then skin defects and Ccl4 liver poisoning injury were established in the animals transplanted bone marrow.The Brdu marked stem cells in bone marrow were observed during injury repair.It indicates that BMSCs have the effect of mobilization and recruitment to engage in the trauma healing.The result proved BMSCs were a source of stem cells in other tissue wound repairing. |
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