Research Containing: proliferation

Microgravity potentiates stem cell proliferation while sustaining the capability of differentiation

by cfynanon 9 June 2015in Biology & Biotechnology No comment

A three-dimensional (3D) clinostat is a device for generating multidirectional G force, resulting in an environment with an average of 10(3) G. Here we report that human mesenchymal stem cells (hMSCs) cultured in a 3D-clinostat (group CL) showed marked proliferation (13-fold in a week) compared with cells cultured under normal conditions of 1 G (group C) (4-fold in a week). Flow cytometry revealed a 6-fold increase in the number of hMSCs double-positive for CD44/CD29 or CD90/CD29 in group CL after 7 days in culture, compared with group C. Telomere length remained the same in cells from both groups during culturing. Group C cells showed increasing expression levels of type II collagen and aggrecan over the culture period, whereas group CL cells showed a decrease to undetectable levels. Pellets of hMSCs from each group were explanted into cartilagedefective mice. The transplants from group CL formed hyaline cartilage after 7 days, whereas the transplants from group C formed only noncartilage tissue containing a small number of cells. These results show that hMSCs cultured in a 3D-clinostat possess the strong proliferative characteristic of stem cells and retain their ability to differentiate into hyaline cartilage after transplantation. On the contrary, cells cultured in a 1-G environment do not maintain these features. Simulated microgravity may thus provide an environment to successfully expand stem cell populations in vitro without culture supplements that can adversely affect stem cell-derived transplantations. This method has significant potential for regenerative medicine and developmental biology.

MECHANOBIOLOGY OF ADULT AND STEM CELLS

by cfynanon 9 June 2015in Biology & Biotechnology No comment

Mechanical forces, including gravity, tension, compression, hydrostatic pressure, and fluid shear stress, play a vital role in human physiology and pathology. They particularly influence extracellular matrix (ECM) gene expression, ECM protein synthesis, and production of inflammatory mediators of many load-sensitive adult cells such as fibroblasts, chondrocytes, smooth muscle cells, and endothelial cells. Furthermore, the mechanical forces generated by cells themselves, known as cell traction forces (CTFs), also influence many biological processes such as wound healing, angiogenesis, and metastasis. Thus, the quantitative characterization of CTFs by qualities such as magnitude and distribution is useful for understanding physiological and pathological events at the tissue and organ levels. Recently, the effects of mechanical loads on embryonic and adult stem cells in terms of self-renewal, differentiation, and matrix protein expression have been investigated. While it seems certain that mechanical loads applied to stem cells regulate their self-renewal and induce controlled cell lineage differentiation, the detailed molecular signaling mechanisms responsible for these mechano-effects remain to be elucidated. Challenges in the fields of both adult- and stem-cell mechanobiology include devising novel experimental and theoretical methodologies to examine mechano-responses more closely to various forms of mechanical forces and mechanotransduction mechanisms of these cells in a more physiologically accurate setting. Such novel methodologies will lead to better understanding of various pathological diseases, their management, and translational applications in the ever expanding field of tissue engineering.

Related URLs:
<Go to ISI>://WOS:000261281700007

Simulated microgravity alters multipotential differentiation of rat mesenchymal stem cells in association with reduced telomerase activity

by cfynanon 9 June 2015in Biology & Biotechnology No comment

Microgravity is one of the most important characteristics in space flight. Exposure to microgravity results in extensive physiological changes in humans. Bone loss is one of the changes with serious consequences: however. the mechanism retains unclear. As the origin of osteoprogenitors, mesenchymal stein cells (MSCs) may play an important role in it. After cultured under simulated microgravity (in a rotary cell culture system, RCCS), MSCs were stained using oil red O to identify adipocytes. The mRNA level of bone morphogenetic protein (BMP)-2 and peroxisome proliferators-activated receptor (PPAR) gamma 2 was determined by RT-PCR. Otherwise, MSCs were induced to osteogenic differentiation after microgravity culture, and then the activity of alkaline phosphatase (ALP) was determined by PNPP and the content of osteocalcin (OC) by ELISA. Furthermore, the telomerase activity in MSCs was measured by TRAP. The results showed that simulated microgravity inhibited osteoblastic differentiation and induced adipogenic differentiation accompanied by the change of gene expression of BMP-2 and PPAR gamma 2 in MSCs. Meanwhile, the telomerase activity decreased significantly in MSCs under simulated microgravity. The reduced bone formation in space flight may partly be due to the altered potential differentiation of MSCs associated with telomerase activity which plays a key role in regulating the lifespan of cell proliferation and differentiation. Therefore. telomerase activation/replacement may act as a potential countermeasure for microgravity-induced bone loss. (C) 2008 Elsevier Ltd. All rights reserved.

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<Go to ISI>://WOS:000259409100033

Proliferation of Rat Mesenchymal Stem Cells in Collagen Sponges Reinforced with Poly(Ethylene Terephthalate) Fibers by Stirring Culture Method

by cfynanon 9 June 2015in Biology & Biotechnology No comment

The objective of this study is to investigate the effect of medium stirring conditions on the proliferation of rat mesenchymal stem cells (MSC) in collagen sponges reinforced by the incorporation of poly(ethylene terephthalate) (PET) fibers. A collagen solution with PET fibers homogeneously dispersed was freeze-dried, followed by dehydrothermal cross-linking to obtain a collagen sponge incorporating PET fibers. MSC were proliferated in the sponge by a stirring culture method. The PET fibers reinforcement significantly suppressed the sponge deformation in culture. The MSC proliferation was enhanced by the stirring culture to a significantly higher extent than that of a static one. Homogeneous distribution of cells proliferated was observed at the stirring rate of 50 rpm and compared with that at lower and higher rates. Combination of the PET fiber-reinforced sponge with the stirring culture method is a promising way to allow cells to homogeneously proliferate in the sponge. (C) Koninklijke Brill NV, Leiden, 2011

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<Go to ISI>://WOS:000308105900008

From spindle to spherical: Is spherical shape a potential predictor of human mesenchymal stem cells with increased differentiation capability?

by cfynanon 9 June 2015in Biology & Biotechnology No comment

Because human mesenchymal stem cells (hMSCs) can proliferate indefinitely in an undifferentiated state and differentiate into various cell types, hMSCs are expected to be useful for cell replacement therapy. But the clinic application is limited by its differentiation efficiency of hMSCs. It has been proved that cells can be geometrically switched between gene programs for growth, apoptosis and differentiation. Previous studies showed that hMSCs started showing round when exposed to modeled microgravity (MMG), while their differentiation capability seemed enhanced simultaneously. Thus, this article briefly reviews such studies, and hypothesizes that “spherical shape” could be a potential predictor of hMSCs with potentiated differentiation capability.

Three-dimensional bioreactor cultures: A useful dynamic model for the study of cellular interactions

by cfynanon 9 June 2015in Biology & Biotechnology No comment

The ex vivo expansion of hematopoietic cells is a developing area with emphasis on bioreactor systems for amelioration of culture conditions. A rational design of bioreactors, especially those allowing microgravity, could permit the production of stem cells and will offer new approaches for studying the mechanisms of proliferation, differentiation, and signal transduction of cultured cells. The efficacy of two commercially available bioreactors (rotating-vessel miniPERM and static INTEGRA CL 350) to support long-term bone marrow cell cultures (LTBMCC) and three-dimensional growth of Hodgkin's lymphoma HD-MY-Z cells was investigated. In the miniPERM system, the growth of LTBMCC spheroids (containing 30-40 cells) was obtained. An essentially higher content of hematopoietic precursor cells (colony-forming units-granulocyte macrophage) was registered in the rotating-vessel system. In this bioreactor, a growth of large HD-MY-Z spheroids (containing 100-200 cells) was achieved. The composed mathematical models of the physicomechanical behavior of spheroids enabled the evaluation of the revolution frequency increase schedule. The differential equations took into account all inertial effects caused by the production module rotation movement as well as those caused by the relative movement of the spheroid in the fluid. The models aimed at the optimization of the rotation frequency increase schedule for different types of cells to reduce shear stress, augment productivity, and tolerate the growth of large spheroids. The models were numerically tested using MATLAB-SIMULINK software, and the trajectories of prestained HD-MY-Z spheroids were filmed. The coincidence of the theoretical and experimental trajectories was sufficient.

Spaceflight alters the migratory ability of stem cell derived keratinocytes resulting in decreased wound healing potential

by cfynanon 9 June 2015in Biology & Biotechnology No comment

Spaceflight is known to have detrimental effects on most systems of the human body, including the musculoskeletal system, immune system and cardiovascular system, whilst also impairing many normal physiological processes, such as wound closure. We hypothesized that somatic stem cells, responsible for tissue regeneration, require mechanical stimulation in the form of gravity to regenerate tissues at normal rates, and that spaceflight conditions, specifically microgravity, may interfere with their proliferation and differentiation resulting in the widespread degeneration of tissues observed in space. We investigated this hypothesis by inducing embryonic stem cells to form embryoid bodies, a model of differentiated tissue, in microgravity for 15 days on shuttle mission STS-131. Results show that there was no alteration in the ability of embryoid bodies to adhere to and spread on a collagen matrix upon return to 1g and there was no difference in viability of flight and ground control samples. However, qRT-PCR analysis indicated that many genes involved in maintenance of stem cell pluripotency failed to turn off and differentiation of normal germlayer markers was inhibited following spaceflight, indicating an alteration in the normal differentiation process. This lead us to conduct a more in-depth experiment to analyse the differentiation process in one specific cell type, the keratinocyte, and additionally to investigate the effects of spaceflight on the ability of keratinocytes to conduct effective wound closure.

Simulated microgravity inhibits the proliferation and osteogenesis of rat bone marrow mesenchymal stem cells (vol 40, pg 671, 2007)

by cfynanon 9 June 2015in Biology & Biotechnology No comment

OBJECTIVES: Microgravity is known to affect the differentiation of bone marrow mesenchymal stem cells (BMSCs). However, a few controversial findings have recently been reported with respect to the effects of microgravity on BMSC proliferation. Thus, we investigated the effects of simulated microgravity on rat BMSC (rBMSC) proliferation and their osteogeneic potential. MATERIALS AND METHODS: rBMSCs isolated from marrow using our established effective method, based on erythrocyte lysis, were identified by their surface markers and their proliferation characteristics under normal conditions. Then, they were cultured in a clinostat to simulate microgravity, with or without growth factors, and in osteogenic medium. Subsequently, proliferation and cell cycle parameters were assessed using methylene blue staining and flow cytometry, respectively; gene expression was determined using Western blotting and microarray analysis. RESULTS: Simulated microgravity inhibited population growth of the rBMSCs, cells being arrested in the G(0)/G(1) phase of cell cycle. Growth factors, such as insulin-like growth factor-I, epidermal growth factor and basic fibroblastic growth factor, markedly stimulated rBMSC proliferation in normal gravity, but had only a slight effect in simulated microgravity. Akt and extracellular signal-related kinase 1/2 phosphorylation levels and the expression of core-binding factor alpha1 decreased after 3 days of clinorotation culture. Microarray and gene ontology analyses further confirmed that rBMSC proliferation and osteogenesis decreased under simulated microgravity. CONCLUSIONS: The above data suggest that simulated microgravity inhibits population growth of rBMSCs and their differentiation towards osteoblasts. These changes may be responsible for some of the physiological changes noted during spaceflight.

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<Go to ISI>://WOS:000253978100014

Cultured stem cells are sensitive to gravity changes

by cfynanon 9 June 2015in Biology & Biotechnology No comment

Stem and precursor cell play an important role in development and regeneration. The state of these cells is regulated by biochemical substances, mechanical stimuli and cellular interactions. To estimate gravity effects We Used two types of cultured stem Cells: human mesenchymal stromal cells (hMSCS) from gone marrow and mice embryonic stem (mESC) line R1. Gravity changes were stimulated by long-term (4-7 days) slow clinorotation and leaded to decreased hMSC proliferation. changes of cell morphology and modified F-actin cytoskeleton, We did not find the shifts ill cell phenotype except for decreased expression of HLA 1 and CD105 Nit excretion of IL-6 into medium increased significantly Remodeling, of cytoskeleton started first 4h and was similar to prepoptotic changes. This data suggested the modification ill cell adhesion and possible commitment of hMSC. It was observed that expression of alkaline phosphatase by MSC ill osteogenic medium was more intensive in control. On the contrary, clinorotation did not change formation of mESC colonies and increased proliferation activity in LIF+ -medium. However the number of embryonic bodies after clinorotation was less than in static control. It is suggested that ESCs kept the viability and proliferative potential but decreased the differentiation ability after changes in gravity stimulation. (c) 2008 Published by Elsevier Ltd.

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<Go to ISI>://WOS:000258632900006

Culture of rabbit bone marrow mesenchymal stem cells and collagen scaffolds under the mimic microgravity environment in vitro

by cfynanon 9 June 2015in Biology & Biotechnology No comment

BACKGROUND:The method of differentiating from bone marrow mesenchymal stem cells(BMSCs) into chondrocytes included in vitro high-density micelle culture,in vitro monolayer cell culture,in vitro three dimensional stent induction,in vitro co-culture induction with chondrocytes and gene transfection.OBJECTIVE:To study adhesion,extension and proliferation of rabbit BMSCs in type Ⅰ and Ⅱ collagen scaffolds under the mimic microgravity environment in vitro.METHODS:BMSCs of rabbits were primarily cultured and subcultured in vitro,and then divided into two groups according to the difference of induction factors:experimental group receiving transforming growth factor(TGF)-β1 and insulin-like growth factor(IGF)-Ⅰ ;blank control group.After three weeks,the two groups were detected by methyl thiazolyl tetrazolium(MTT) assay,measurement of glycosaminoglycan(GAG) and immunohistochemistry.Chondrocytes in the experimental group were incubated in type Ⅰ and Ⅱ collagen scaffolds,and then divided into four groups:group 1:chondrocytes and type Ⅱ collagen scaffolds co-cultured statically;group 2:chondrocytes and type Ⅱ collagen scaffolds co-cultured under the mimic microgravity environment;group 3:chondrocytes and type Ⅰ collagen scaffolds co-cultured statically;group 4:chondrocytes and type Ⅰ collagen scaffolds co-cultured under the mimic microgravity environment.One week later,hematoxylin-eosin staining and toluidine blue staining were performed.RESULTS AND CONCLUSION:The results of the MTT assay(absorbance value) and the GAG content in experimental group were higher than in blank control group.Immunohistochemical detection of collagen Ⅱ was positive in experimental group.Results from hematoxylin-eosin staining and toluidine blue staining have demonstrated that composited cell number in type Ⅱ collagen scaffolds was evidently more than that of type Ⅰ collagen.Composited cell number under the mimic microgravity environment was evidently more than that of static culture in the same scaffold.Above-described results have confirmed that the mimic microgravity environment is conducive to adhesion and proliferation of high-density cells,and contributes to signal transmission among cells to provide suitable microenvironment for maintaining cell growth and metabolism.Collagen type Ⅱ scaffold can be used as a more satisfying scaffold material for chondrocytes than collagen type Ⅰ

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Research Containing: proliferation

Microgravity potentiates stem cell proliferation while sustaining the capability of differentiation

MECHANOBIOLOGY OF ADULT AND STEM CELLS

Simulated microgravity alters multipotential differentiation of rat mesenchymal stem cells in association with reduced telomerase activity

Proliferation of Rat Mesenchymal Stem Cells in Collagen Sponges Reinforced with Poly(Ethylene Terephthalate) Fibers by Stirring Culture Method

From spindle to spherical: Is spherical shape a potential predictor of human mesenchymal stem cells with increased differentiation capability?

Three-dimensional bioreactor cultures: A useful dynamic model for the study of cellular interactions

Spaceflight alters the migratory ability of stem cell derived keratinocytes resulting in decreased wound healing potential

Simulated microgravity inhibits the proliferation and osteogenesis of rat bone marrow mesenchymal stem cells (vol 40, pg 671, 2007)

Cultured stem cells are sensitive to gravity changes

Culture of rabbit bone marrow mesenchymal stem cells and collagen scaffolds under the mimic microgravity environment in vitro