Johnson KR, Leight JL, Weaver VM. Demystifying the effects of a three-dimensional microenvironment in tissue morphogenesis.
In this paper, the researchers mainly focuses on the relationship between the surrounding environment (matrix) and tissue/cell morphogenesis and homeostasis. By understanding how tissues and cells' behavior changes in response to its 3D environment will aid the construction of tissues in vivo that actually would develop and function like the model tissue or organ. In their study, 3D organotypic models are created to study the mechanisms of epithelial morphogenesis and tissue homeostasis. As a result, the scientists found out that there is a critical role being played by the microenvironment in regulating the function and signaling of mammalian tissue.
The experiment designed by the researcher seeks to explore the role of extracellular matrix signaling and tissue organization in epithelial survival. Using breast cancer cells, the experiment shows mammary tissues can resist apoptotic stimuli by activating NF-B through 64 integrin-dependent Rac-Pak1 signaling (occurs in extracellular matrix) and thus, emphasize the importance of the extracellular matrix stroma in tissue survival and suggest that 64 integrin-dependent Rac stimulation of Pak1 could be an important mechanism mediating apoptosis-resistance in some breast tumors.
The experiment make use of two non-malignant human MEC models and a reconstituted, laminin-rich rBM by growing MECs on top of rBM (2D culture) and compared their death-resistance behavior with that of mammary acini embedded within rBM (3D culture). As result, the researchers compared the cells grown as 2D monolayers and epithelial cells assembled into 3D spheroids; finding that 3D assembled cells are more resistant to apoptosis to a degree that is similar to that exhibited by multidrug-, immune- and radiation-resistant tumors. Accordingly, the increased survival behavior of 3D spheroids has been largely attributed to compromised drug penetration and altered cell-cycle dynamics. With this, we can see the importance of the extracellular matrix context in the regulation of homeostasis and growth of cells and tissues.
This paper is very suitable for our project as we also like to compare the matrix and cell growth rate. In our group project, we seek to explore the effect of extracellular matrix stiffness and various anti-cancer drugs to the growth of brain tumor cells. We plan to make different extracellular environments mainly by altering the stiffness of the matrix to which we implant the cells in. Furthermore, the addition of some anti-cancer drugs would demonstrate how easily the drug can get to the cells through the matrix. As a result, we can see the status of the tumor cells via live and dead assay to draw conclusion about the growth rate/destruction of the brain tumor cells.
2 comments:
Very interesting: I like the study's approach in studying various 3D-microenvironments' effects in cell's survival as well as changes in the overall morphogenesis. I completely agree with: "By understanding how tissues and cells' behavior changes in response to its 3D environment will aid the construction of tissues in vivo that actually would develop and function like the model tissue or organ." For instance, in regards to the paper I posted (Tissue Engineering of Complex Tooth Structures...), in order to successfully construct artificial teeth, one of molecular mechanisms that need to be understood include how enamel tissue interacts with its ECM. Once enamel initiates at the DEJ, its overall growth is known to be highly guided by amelogenin (ECM matrix protein). It is still unknown how amelogenin successfully creates the suitable 3D-microenvironment to guide the hydroxyapatite growth in highly organized manner (c-axial direction). More interestingly, these amelogenin matrix completely disappear during the enamel maturation.
Lastly, you mentioned that: "we seek to explore the effect of extracellular matrix stiffness and various anti-cancer drugs to the growth of brain tumor cells." I was wondering how you plan to alter the stiffness of the matrix which your brain tumor cells will be implanted in? (ie. what are the parameters?) If you plan on using neurons, laminin (ECM) is known to have a function in axon guidance. If the anti-cancer drugs possibly interact with laminin to block the downstream signling of axon growth (hence inhibiting neurite growth), that could ultimately result in destruction of the brain cells. Just some random thoughts that came up while reading your comments... :^) Thanks!
We will be altering stiffness by changing ratio of acrylamide to bis-acrylamide when we are making the gels. Also for our project, we will only have brain tumor cells and not regular brain cells, so its hard to say at this point what the drugs' affect will be on normal cells. However, for our project, we will have 3 types of drugs and will be only interested in the viability of the tumor cells when implanted into different stiffness ratio of ECM(gels).
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