Hematopoietic Regulation Mechanisms, November 29, 2004

Hematopoietic Regulation Mechanisms, November 29, 2004

① Bone marrow hematopoietic microenvironment; ② Immune factors; ③ Neural mediators; ④ Humoral factors.

Among these four factors, the hematopoietic microenvironment is the most important. It is the decisive factor that enables hematopoietic cells to differentiate, proliferate, and mature. Thus, the relationship between the hematopoietic microenvironment and hematopoietic cells is like that between soil and seeds. The hematopoietic microenvironment includes blood vessels, nerves, and stroma. The stroma consists of marrow stromal cells, fibroblasts, and extracellular matrix cells, with marrow stromal cells being the primary component. In 1974, Dtxt et al. first established an in vitro bone marrow culture system, creating an experimental model that simulates the hematopoietic microenvironment outside the body, thereby laying the groundwork for further research into hematopoietic regulation mechanisms. The in vitro hematopoietic microenvironment requires a well-formed adherent cell layer that can induce hematopoiesis, primarily supporting the proliferation and directed differentiation of hematopoietic stem cells in vitro. The bone marrow’s hematopoietic microenvironment is extremely similar to the in vitro bone marrow culture system. The main stromal cells in the bone marrow’s hematopoietic microenvironment are four types: fibroblasts, macrophages, endothelial-like cells, and adipocytes. These four cell types support and nurture the bone marrow’s hematopoietic function. The proliferation and differentiation of pluripotent stem cells depend on the induction and regulation provided by the bone marrow’s hematopoietic microenvironment, with the differentiation and directional commitment of pluripotent stem cells (CFU) being induced by one of the aforementioned four bone marrow stromal cell types.

In summary, when evaluating drug efficacy, bone marrow in vitro culture techniques are typically employed to observe the effects of drugs on bone marrow stromal cells (CFU-F), granulocyte-macrophage progenitor cells (CFU-GM), and splenic colony-forming units (CFU-S).