[Effects of Platelet-Rich Plasma on Macrophage Phenotype and Its Influencing Factors]

OBJECTIVE

To evaluate the effects of platelet-rich plasma (PRP) supernatants with different activation methods and storage time on human monocyte-derived macrophages phenotype and explore the possible mechanism.

METHODS

Human monocyte-derived macrophages were cultured in vitro with PRP or activated PRP supernatants activated with different activators. The expression of marker molecules on the surface of macrophages was detected by flow cytometry, and the concentration of growth factors in PRP supernatants was detected by ELISA.

RESULTS

After 24 h of coculture, the expression level of CD86 in macrophages stimulated by PRP supernatant (thrombin and Cacl2 activated) was significantly higher than that by PRP group (P<0.05), and the expression of CD163 in macrophages was increased by Cacl2 activated PRP supernatant. Compared with different activator groups, the expression of CD163 in macrophages of Cacl2 activated group was significantly higher than that of thrombin and ADP groups (P<0.05). ELISA results showed that the concentrations of FGF (P<0.001) and EGF (P<0.05) in the supernatant of PRP stored at -80 ℃ for more than 20 months and 10-20 months were significantly higher than those in the group stored at less than 10 months after Cacl2 activation, and the expressions of CD86 (P<0.01), CD163 (P<0.001) and CD206 (P<0.001) in macrophages cocultured with the supernatant of the two groups were significantly increased.

CONCLUSION

PRP activated by different activators has different effects on the phenotype of macrophages. Meanwhile, the storage time will also affect the growth factor concentration and effect of PRP.

[Research Progress on the Mechanism of Macrophages Regulating Hematopoiesis in Bone Marrow Microenvironment--Review]

Bone marrow macrophage is an important component of bone marrow microenvironment, which is closely related to hematopoietic regulation and hematopoietic stem cell transplantation(HSCT). Recent studies have shown that bone marrow macrophage is an important part of hematopoietic stem cell niche, which can help regulate the mobilization and function of hematopoietic stem/progenitor cells. After HSCT, the microenvironment of bone marrow is damaged and a large number of macrophages infiltrate into the bone marrow. Regulating the macrophage-related signal pathways can promote the recovery of hematopoiesis and the reconstruction of hematopoietic function. Co-culture of macrophages and hematopoietic stem cells (HSC) in vitro significantly increased the number of HSCs and their ability of clone formation, which suggests that macrophages play an important role in the regulation of hematopoiesis in the hematopoietic microenvironment of bone marrow. This paper reviews the recent research progress on the role of macrophages in bone marrow hematopoietic microenvironment.

Erythrocyte-derived extracellular vesicles aggravate inflammation by promoting the proinflammatory macrophage phenotype through TLR4-MyD88-NF-κB-MAPK pathway

Transfusion of stored erythrocytes is associated with the increased risk of morbidity and mortality in critical infections, but the mechanism is incompletely understood. Previous studies have suggested that RBC-derived extracellular vesicles (EVs) may be potential risk factors for the occurrence of transfusion-related immunomodulation. The purpose of our study was to evaluate the effects of RBC-derived EVs under inflammatory conditions and explore the underlying mechanisms. In vivo, the activity of EVs was evaluated in cecal ligation and puncture (CLP)-induced sepsis. Our results showed that EVs significantly aggravated the inflammatory response to sepsis in serum and lung tissue by promoting the production of the proinflammatory factors tumor necrosis factor-α (TNF-α）-interleukin-6(IL-6), and interleukin-1β (IL-1β) and reduced the survival rate of septic mice in vivo. Importantly, adoptive transfer of EVs-pretreated bone marrow-derived macrophages (BMDMs) obviously aggravated systemic proinflammatory factors in mice after CLP surgery. In vitro, the proinflammatory properties of EVs were shown to elevate TNF-α, IL-6, and IL-1β levels in lipopolysaccharide (LPS)-stimulated BMDMs. Moreover, EVs promoted LPS-induced macrophage polarization into a proinflammatory phenotype. The underlying mechanism might involve EV-mediated up-regulation of TLR4-MyD88-NF-κB-MAPK activity to favor macrophage cytokine production.