Research Progress of the Effect of Microgravity on Cellular Senescence / 医用生物力学

Microgravity is a typical feature of the space. A large number of space flights and foundation simulation experiments have shown that cells show typical biological characteristics of aging, such as reduced cell proliferation and cell cycle arrest under microgravity or simulated microgravity. However, the molecular mechanism by which microgravity or simulated microgravity affects cellular senescence is not well understood. Understanding the mechanism controlling cellular senescence induced by microgravity environment is helpful for exploring anti-aging strategies and targeted interventions in space. In recent years, domestic and foreign scholars have carried out a number of researches and explorations on the effect of microgravity and simulated microgravity on cellular senescence as well as the related mechanisms. In this review, the latest research progress of this filed was summarized.

Mesenchymal stem cells and skin injury repair / 生物医学工程学杂志

Mesenchymal stem cells (MSCs) are pluripotent stem cells with high self-proliferation and multidirectional differentiation potential. They also have other functions including immune regulation, paracrine and so on, playing an important role in repairing injured tissues. In recent years, a lot of research has been done on how MSCs promote skin injury repair, and a lot of progress has been made. Compared with direct injection of MSCs in the wound area, some special treatments or transplantation methods could enhance the ability of MSCs to repair skin injury. This paper mainly discusses the role of MSCs in skin injury repair and technical ways to improve its repairing capacity, and discusses the existing problems in this field and prospects for future research directions.

Mechanical Heterogeneity of Tumor Tissues and Epithelial-Mesenchymal Transition of Tumor Cells / 医用生物力学

In the process of tumor growth, with the proliferation and expansion of cancer cells, the reconstruction of extracellular matrix (ECM) of cancer tissues, the restriction of surrounding tissues and the flow of cancer tissue interstitial fluid, the special stress environment is formed in the tumor tissues. Significant differences are found in the mechanical environment and mechanical characteristics of different regions of tumor tissues, that is, mechanical heterogeneity. The reseach shows that the mechanical properties of tumor tissue invasion frontier areas are more significant and complex. In particular, the epithelial-mesenchymal transition (EMT) of tumor cells also prefers to concentrate on this area. The mechanical stress generated by the invasion front can induce EMT of tumor cells through TWIST1, TGF-β, WNT and other force signal transduction pathways, and promote tumor cell invasion. From the perspective of tumor biomechanics, this review focuses on the relationship between mechanical heterogeneity of tumor cells and EMT, so as to provide the theoretical basis for mechanoenvironment-targeted therapy of tumors.

Effects of Matrix Stiffness on Proliferation and Glucose Metabolism of Hepatocellular Carcinoma Cells / 医用生物力学

Objective To investigate the influences of different matrix stiffness on proliferation ability and glucose metabolism of hepatocellular carcinoma (HCC) cells and to explore the correlation between metabolism and biological behavior changes of HCC cells resulted from the stiffness of extracellular matrix (ECM)．Methods The proliferation changes of HepG2 cells cultured on matrix with different stiffness were detected by CCK-8 assay and cell count assay. 2-NBDG and flow cytometry were used to detect the effect of matrix stiffness on glucose uptake. Real-time fluorescence quantitative polymerase chain reaction (qRT-PCR) was used to detect the expression level of Glut1. Then, 2-DG was used to inhibit glycolysis, and the influences of matrix stiffness on proliferation of HepG2 cells were detected. Results The proliferation ability, glucose uptake and the expression of Glut1 of HepG2 cells increased with the matrix stiffness increasing. When glycolysis was inhibited, the proliferation ability of HepG2 cells grown on matrix with different stiffness was similar. Conclusions The mechanical microenvironment had an important effect on proliferation of HCC cells; matrix with a larger stiffness might promote proliferation of HCC cells through regulating glycolysis. The research findings provide a corresponding experimental basis for the clinical treatment of HCC cells and drug development targeting glucose metabolism.

Regulation of tumor cell glycometabolism and tumor therapy / 生物医学工程学杂志

Tumor cells have unique energy metabolism phenomena, namely high glucose absorption, aerobic glycolysis and high lactic acid production, which are characterized by down-regulation of related proteins involved in oxidative metabolism in tumor cells, and up-regulation of glucose transporters and monocarboxylate transporters. Studies have shown that drugs that target tumor cell glucose metabolism have the ability to selectively kill tumor cells, bringing new hope for tumor treatment. Tumor stem cells are considered to be the root cause of tumor recurrence, metastasis and poor prognosis, and their energy metabolism characteristics have not yet been agreed. Studies have shown that reversing the energy metabolism of tumor stem cells can increase their chemosensitivity. This article reviews recent studies on tumor and tumor stem cell glucose metabolism and the opportunities and challenges of tumor treatment through targeting glucose metabolism, which might provide new ideas and opportunities for clinical tumor therapy.

Effect of Osteopontin on Nuclear Mechanics of Bone Marrow Mesenchymal Stem Cells and Its Involved Molecular Mechanisms / 医用生物力学

Objective To study the effects of osteopontin (OPN) on the nuclear mechanics of bone marrow-derived mesenchymal stem cells (BMSCs) as well as its involved mechanisms. Methods The BMSC migration was evaluated using the Transwell assay. An atomic force microscope (AFM) was used to determine the elastic modulus of the BMSC nucleus and analyze the changes in the nuclear mechanics of the BMSCs after treatment with OPN. The activation of focal adhesion kinase (FAK) and extracellular signal-regulated kinase1/2 (ERK1/2) was measured by Western blot. The role of the FAK-ERK1/2 signaling pathway in mediating the OPN-affected BMSC nuclear mechanics was investigated by employing a specific inhibitor. RT-PCR and Western blot were used to detect the expression of Lamin A/C at mRNA and protein levels in the BMSCs, respectively. Results The elastic modulus of the BMSC nucleus exhibited a significant decrease after OPN treatment compared with that of the control group. OPN could upregulate the phosphorylation level of FAK and ERK1/2, but the inhibitor of FAK or ERK1/2 restored the OPN-decreased elastic modulus of the BMSC nucleus and inhibited the BMSC migration significantly. After treatment with OPN, the expression of Lamin A/C in the BMSCs reduced significantly, and such a reduced expression could be suppressed by the inhibitor of FAK or ERK1/2. Conclusions OPN could probably downregulate the expression of Lamin A/C of the BMSCs via the FAK-ERK1/2 signaling pathway, decrease the stiffness of the BMSC nucleus, and promote the migration of the BMSCs. The research outcomes provide the experimental evidence for further understanding the mechanism of the OPN-regulated BMSC migration and its potential clinical application.

Effect of fructose and dithiothreitol on cell viability and pluripotency of cryopreserved bone marrow mesenchymal stem cells / 中国组织工程研究

BACKGROUND:Cel cryopreservation is required for clinical use of stem cel s, and the current process of cryopreservation however may be harmful to cel viability, pluripotency and differentiation capacity. OBJECTIVE:To explore the effect of fructose and dithiothreitol on pluripotency and osteogenesis of cryopreserved bone marrow mesenchymal stem cel s. METHODS:Bone marrow mesenchymal stem cel s were isolated from the bone marrow of Sprague-Dawley rats and pretreated with fructose (200μmol/L), dithiothreitol (500μmol/L) or combined components before cryopreservation. Then the cel s were cryopreseved for 6 months and the morphology of cel s was observed by inverted microscopy. The cel viability was evaluated by MTT, and real-time PCR was used to detect the mRNA expression of Nanog, OCT4 and Sox2. Alkaline phophatase activity assay and alizarin red staining were utilized to detect the osteogenic capacity of bone marrow mesenchymal stem cel s. RESULTS AND CONCLUSION:Images captured by inverted microscopy showed no significant difference in cel morphology between groups. The MTT results indicated that fructose and combined pretreatment could promote the cel viability of bone marrow mesenchymal stem cel s after cryopreservation, while the real-time PCR results demonstrated that dithiothreitol significantly facilitated the expression of Naogo and Sox2 in bone marrow mesenchymal stem cel s. Moreover, ALP activity assay and alizarin red staining confirmed the positive effects of fructose, dithiothreitol and combined pretreatment on osteogenic capacity of bone marrow mesenchymal stem cel s after cryopreservation, and the best effects were found after pretreatment with dithiothreitol and combined components. Overal , these findings indicate that fructose pretreatment is beneficial for cel viability of cryopreseved bone marrow mesenchymal stem cel s, and dithiothreitol contributes to maintaining the pluripotency and osteogenesis capacity of cryopreseved bone marrow mesenchymal stem cel s.

Effect of Conditioned Medium from Endothelial Cells on Cancer Stem Cell Phenotype of Hepatoma Cells / 生物医学工程学杂志

In this study, we aimed to investigate the influences of conditioned medium from human umbilical vein endothelial cells (HUVEC) on cancer stem cell phenotype of human hepatoma cells. HUVEC and human hepatoma cells (MHCC97H) were cultured, respectively, and then the MHCC97H cells were co-cultured with conditioned medium from HUVEC (EC-CM) with Transwell system. Anti-cancer drug sensitivity, colony-formation, migration/invasion ability, expression of cancer stem cell marker and sphere formation were performed to determine the cancer stem cell phenotype in MHCC97H cells. We found that MHCC97H cells co-cultured with EC-CM exhibited significantly higher colony-formation ability and lower sensitivity of anti-cancer drugs 5-FU and Cis. Transwell assay showed that treatment with EC-CM obviously increased migration and invasion of MHCC97H cells. Moreover, increased sphere forming capability and expression of CD133 in MHCC97H cells were observed after co-cultured with EC-CM. These results suggested that EC-CM could promote cancer stem cell phenotype of hepatoma cells.

Novel therapeutic strategies for treatment of hepatocellular carcinoma: targeting intervention on liver cancer stem cells / 生物医学工程学杂志

Hepatocellular carcinoma (HCC) is one of the most common human malignant tumors worldwide; it is also hard to prevent its metastasis and recurrence by traditional treatments. Up to now, how to prevent and treat HCC is still a challenging problem in clinic. Cancer stem cells (CSCs) are cells within malignant tumor that possess the capacity to self-renew and differentiate to lead to the heterogeneous lineages of cancer cells that comprise the tumor, and are the root to cause metastasis, recurrence and bad prognosis of the cancer. Targeting CSCs is a novel therapeutic strategy for management and treatment of the cancer. In recent years, targeting intervention on liver cancer stem cells (LCSCs) gradually became a novel strategy for HCC treatment, and some exciting research results in the treatment of HCC were also achieved. In this review, we introduce the biological characteristics of LCSCs and highlight the therapeutic strategies for hepatocellular carcinoma by targeting intervention on LCSCs.

Roles of matrix metalloproteinase in migration and differentiation of bone marrow-derived mesenchymal stem cells / 生物医学工程学杂志

Matrix metalloproteinases (MMPs) are endocellular proteolytic enzymes. They are so named because they need Ca2+, Zn2+ and other metal ions as their cofactors. MMPs play an important biological role in regulating the formation, remodeling and degradation of extracellular matrix and participate in various physiological and pathological processes of cells. Bone marrow-derived mesenchymal stem cells (BMSCs) are a kind of pluripotent stem cell which has the ability to self-renew and differentiate into functional cells. Meanwhile, they can respond to the damage signals and migrate to injured site for tissue repair and regeneration. MMPs and their inhibitors TIMPs affect the differentiation and migration of BMSCs. This article reviews the roles of MMPs in differentiation and migration of BMSCs.

Research progresses of paracrine effect of bone marrow derived mesenchymal stem cells on wound healing / 生物医学工程学杂志

Bone marrow derived mesenchymal stem cell (BMSC) is one of the crucial cell types which plays roles in wound healing of tissues. In the last decades, it was believed that BMSCs promoted wound healing by differentiating into multiple lineages and placing the wounded tissues. In recent years, a new viewpoint arose from evidences that the paracrine effect of BMSCs might play a more important role in the process of wound healing than differentiation. Understanding the role of BMSCs paracrine in wound healing would be vital to clarify the mechanism how BMSCs take part into the process of wound healing. In this paper, we review the new research processes of BMSCs paracrine in wound healing of tissues.

A two-phase culture system for megakaryocyte differentiation of human mobilized peripheral blood CD34+ cells / 生物医学工程学杂志

In our study, a two-phase culture system was developed to acquire large amount of CD41+ and polyploidy cells. Human mobilized peripheral blood CD34+ (PB CD34+) cells were first cultured in expansion medium (Cocktail or CC100 medium) for 3,4,5 or 6 days, and then cultured in megakaryocytic differentiation medium containing TPO and SCF for additional 7, 8 or 9 days. Cell expansion, morphology, CD41+ cell percentage and DNA content were investigated to evaluate the protocol. The result showed that more CD41+ and polyploidy cells could be obtained following the two-phase culture with Cocktail medium than with CC100. Moreover, with 3 days expansion in Cocktail medium plus 7 days in differentiation medium, the initial CD 34+ cells obtained 16-fold expansion of CD41+ cells and 3-fold expansion of polyploidy cells, such obtained level being significantly higher than that of culturing cells with only one step in TPO or TPO+SCF. We conclude that with the two-phase culture system, PB CD34+ cells can expand and differentiate to more CD41+ and polyploidy cells than those cultured only in accordance to the one-stage culture protocol, so a new and highly efficient megakaryocyte differentiation model for megakaryocyte and platelet related researches is provided already.

Biological effects and their applications in medicine of pulsed electric fields / 生物医学工程学杂志

Pulsed electric fields can induce various kinds of biological effects that are essentially different from the normal electric fields, especially the interactions of Nanosecond Pulsed electric field (nsPEF) with cells. The biological effects of different pulsed electric fields on cell membranes, cytoplasmic matrixes, cell growth are introduced in this paper. Based on these effects, some applications of pulsed electric fields in cancer therapy, gene therapy, and delivery of drugs are reviewed in details.

Research progress of the drug screening technology in type 2 diabetes mellitus / 生物医学工程学杂志

With the incidence of type 2 diabetes mellitus increasing year after year, the technology of drug screening of type 2 diabetes mellitus progress rapidly, from the level of animal screening to cellular and molecular screening model, from the traditional drug screening technology to high efficient and throughput screening. This paper will summarize the technology of drug screening in the therapy of type 2 diabetes mellitus.

The adhesive mechanical properties of renal tubular epithelial cells on matrigel / 中国医学物理学杂志

purpose: to investigate the adhesive properties of renal tubular epithelial cells on matrigel and compared with the following three cases: ischemia、hypoxia and ischemia & hypoxia(I/H).materials and methods: A micropipette aspiration technique was adopted to determine the adhesive mechanics of renal tubular epithelial cells on matrige. results: it showed that the adhesion of renal tubular epithelial cells on matrigel was higher than that of those three model, further more, a different factor was followed by different adhesive mechanic. conclusion: the adhesion of I/H is lower, the ischemia is higher, but all were lower compared with control. It suggested that effect of hypoxia on adhesive properties of renal tubular epithelial cells on matrigel is bigger than that of ichemia.