Durotaxis is the migration of cells based on the structural gradients of the extracellular matrix. The structural properties are broken up into two types: porosity and stiffness.[1] These mechanical changes are instrumental in the regulation of cellular behavior such as differentiation, proliferation, motility, and migration.[1]
Durotaxis is the migration of cells based on the structural gradients of the rigidity of the substrate (referring to ECM, bone, or any scaffold construct)(figure1).The elastic modulus is used to measure the stiffness of the substrate which changes with each cell type.[1] The cells typically migrate in the direction of higher stiffness (figure 2).[2] The rigidity of the substrate is known to affect migration, immunology, morphology, motility, and various other processes due to the interactions between the extracellular matrix and the cytoskeleton.[1](figure 3)
Cellular migration is controlled by the focal adhesion of cells and cytoskeleton of the immobilized proteins and rearrangement of the cytoskeletal wall affect the rigidity of the ECM and thus affect the ability of cells to migrate throughout the body.
The stiffness of the substrate allows cells to generate forces using focal actin-myosin complexes onto the the substrate. These forces produce focal adhesion kinases which controls the overall structure of the cytoskeleton. The cytoskeleton is highly dependent on the stiffness of the substrate which is important because the cytoskeleton determines the morphology of the cell as well as the chemical responses in the signaling pathways. Controlling the stiffness is therefore key in generating the type of cell that is needed.[3]
Figure 2 displays the process of cell-ECM adhesion via integrin proteins. It should be noted that cell-cell adhesion is similar; however, cadherin proteins are the driving adhesive substrate.[[Image:CellAdhesion.jpg|thumb|left|250px| '''Figure 2.'''Cellular Adhesion [12]]] For further details of cellular adhesion, see Chapter 4 of the Wiki Pages. Cellular locomotion is mediated by several different forces. Figure 3 displays the process. For further information, see Chapter 8 in the Wiki Pages. [[Image:Celllocomotion.jpg|thumb|right|250px| '''Figure 3.'''Cellular Locomotion [14]]]]
Figure 2 shows the elongation that is experienced by the cells when they sense stiffness
Figure 3 shows the affects of different cellular cross linkages on migration. [[Image:Cellmigration.jpg|250px| '''Figure 3.'''Cellular migration using different scaffolds [3]]]]
== History ==
== History ==
▪1880s: First studies of chemotaxis (Engleman)
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▪1892: Ramón y Cajal predicted axons navigate in response to gradients of cues
▪1892: Ramón y Cajal predicted axons navigate in response to gradients of cues
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▪1914: Substrate is important to migration (Harrison)
▪1914: Migration occurs due to the substrate in the microenvironment (Harrison)
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▪1965: Haptotaxis via Pd adhesion assay (Carter)
▪1990's: Cytoskeletal stiffness, morphology, motility, and fibronectin fibril assembly was proven to influence migration
▪ 20th century: It was discovered that cells could detect and respond to substrate stiffness
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Today: Debate among scientists about the differences between Haptotaxis and Chemotaxis; applications of cellular process
== Motivation ==
== Motivation ==
Because this cellular process is important in the immune response, development and wound healing, it is an attractive candidate for exploitation in regenerative medicine. [3] For these reasons, there have been a surge of research in the attempt at creating cellular gradients to direct the process of tissue development [3, 4, 5, 6, 7, 8, 9] .
Understanding how to stimulate or inhibit the migration of cells is crucial for cellular regeneration and treatment. The medical field is driving the need for this research to potentially solve problems like host rejection makes durotaxis in engineering a hot topic.
== Stem Cell Differentiation ==
There have been several different developments among researchers in the use of Haptotaxis and its properties in tissue engineering and regenerative medicine efforts. Notably, the use of stem cells seeded certain grafts to induce tissue and differentiation proliferation [5] In these studies, there is an overarching goal to create tissue derived from human cells to be incorporated in vivo. These studies can affect a vast range of people, including those who with bone deficiencies and tissue deformations and/or deficiencies. [5].
As an example, there has been development in the creation of a human mesenchymal stem cell (hMSC) seeded polymer bone grafts. The grafts are designed to be porous to allow access to certain growth factors. In doing so, a chemical gradient is created, in which draws certain cells to certain areas to proliferate and differentiate. Further, stiff, rod-like fibers are incorporated into the graft to act as guides for the cell. By doing so, the hMSCs can differentiate into osteoblasts, allowing for incorporation in vivo [7].
== Microfluids to create chemical gradients ==
== Bone Scaffolds ==
There has also been work in using microfluids in the creation of a chemical gradient to exploit Haptotaxic properties [10]. By the creation of a gradient, cellular migration - along with differentiation and proliferation - can be studied and exploited in the use of regenerative medicine and tissue engineering.
For years, doctors have been using allograft bone transplants and other replacement methods that are cost inefficient, cause inflammation, extensive pain, and are prone to rejection or replacement after so many years of use. Recent studies in the mechanical properties of bone have produced a bone scaffold that has similar rigidity and porosity to real bone and would allow for the integration of cells completely in less than four weeks. This is possible because the scaffold mimics the stiffness of the mesenchymal stem cells. As said before, the mimicry of the rigidity of the ECM allows for the bound stem cells to create focal adhesion forces which give the the cytoskeletal organization. The organization of the of the cytoskeleton is what gives the cells their shape and thus function.[4][5][6]
As an example, one group varied adhesive ligands through a 3D collagen gel to create a Haptotaxis gradient. By planting a chick embryo dorsal root ganglion into the scaffold, the growth of neural cells was measured. The results suggested that the incorporation of gradients improved regeneration of axons -- suggesting the growth of neural tissue.
== Haptotaxis in Cancer ==
Interestingly, tumor cells possess strong Haptotaxis properties. Tumor cells use the properties of Haptotaxis to metastasize and spread, furthering their effects on the body. Though not much is known about the process, it has been hypothesized that vibronectin, a glycoprotein of which promotes cellular spreading, helps create a gradient of which assists tumor cells mestastize. [4] However, work in understanding the process of cellular migration through Haptotaxis could lead to a greater understanding of cancer metastasis.
== Durotaxis in Cancer ==
Cancer cells use durotaxis extensively affecting the lives of more than 200,000 people every year. One of the key properties that enable cancer to succeed is its stiffness. Tumors can be found to be as much as 10 times stiffer than the normal breast tissue this dramatic gradient causes the pull of endothelial cells to its mass allowing for tumor growth and for metastasis. [4] By finding ways to counteract these properties doctors could slow down the progression of cancer and make treatment more successful.
== Conclusions ==
== Conclusions ==
Work in tissue engineering and regenerative medicine by using Haptotaxis as a vehicle to create specific tissue regeneration is promising. With many different types of biocompatible grafts and the use of stem cell differentiation, and with promising results, it would seem in vivo generation of tissue might happen. However, there are pitfalls to this approach - first of which, specific stem cell differentiation is difficult and can often lead to different desired products. Further, the creation and maintenance of a chemical gradient is difficult in vivo. Additionally, the 3D microenvironment is incredibly influential to the properties of Haptotaxis and can be difficult to replicate [6]. However, technology is advancing in the creation of 3D hydrogels. Lastly, the use of people’s cells is expensive and difficult to procure.
Tissue engineering and regenerative medicine have recently been found to be greatly affected by the durotaxic properties of the ECM. Engineers have been able to use the information that they have recently discovered to make huge advances in cancer research and bone replacement with more improvements guaranteed to come. Hopefully scientists will be able to answer more questions using the research they find with gradient hydrogels and experimentation.
== References ==
== References ==
[1] Lo, Chun-Min, et al. "Cell movement is guided by the rigidity of the substrate." Biophysical journal 79.1 (2000): 144-152.
[1] Ulrich, Theresa A., Elena M. de Juan Pardo, and Sanjay Kumar. “The Mechanical Rigidity of the Extracellular Matrix Regulates the Structure, Motility, and Proliferation of Glioma Cells.” Cancer research 69.10 (2009): 4167–4174.
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Line 48:
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[3]Basan, Markus, et al. "Alignment of cellular motility forces with tissue flow as a mechanism for efficient wound healing." Proceedings of the National Academy of Sciences 110.7 (2013): 2452-2459.
[3]Sant, Shilpa et al. “BIOMIMETIC GRADIENT HYDROGELS FOR TISSUE ENGINEERING.” The Canadian journal of chemical engineering 88.6 (2010): 899–911.
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[4]Basara, Michael L., et al. "Stimulation of haptotaxis and migration of tumor cells by serum spreading factor." Cancer research 45.6 (1985): 2487-2494.
[4]Breuls, Roel G.M, Timothy U Jiya, and Theo H Smit. “Scaffold Stiffness Influences Cell Behavior: Opportunities for Skeletal Tissue Engineering.” The Open Orthopaedics Journal 2 (2008): 103–109.
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[5]Ricoult, Sébastien G., Timothy E. Kennedy, and David Juncker. "Substrate-bound protein gradients to study haptotaxis." Frontiers in bioengineering and biotechnology 3 (2014): 40-40.
[5]Quintero, Andres J, et al. “Stem Cells for the Treatment of Skeletal Muscle Injury.” Clinics in sports medicine 28.1 (2009): 1–11. PMC. Web. 21 Mar. 2017.
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[6]Subramony, Siddarth D., et al. "The guidance of stem cell differentiation by substrate alignment and mechanical stimulation." Biomaterials 34.8 (2013): 1942-1953.
[6]Isenberg, Brett C. et al. “Vascular Smooth Muscle Cell Durotaxis Depends on Substrate Stiffness Gradient Strength.” Biophysical Journal 97.5 (2009): 1313–1322. PMC.
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[7]Chen Jianbo, Paetzell, Emily, Zhou, Jikou, Lyons, Lauren, & Soboyejo, Wole (Jun 2010). Osteoblast-like cell ingrowth, adhesion and proliferation on porous Ti-6Al-4V with particulate and fiber scaffolds. Materials Science and Engineering C, Biomimetic Materials, Sensors and Systems, 30(5), 647-656. doi:101016/jmsec201001005
[7]Wang, N; Butler, JP; Ingber, DE (21 May 1993). "Mechanotransduction across the cell surface and through the cytoskeleton.". Science. 260 (5111): 1124–7.
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[8] Holtorf, Heidi L., et al. "Flow perfusion culture of marrow stromal cells seeded on porous biphasic calcium phosphate ceramics." Annals of biomedical engineering 33.9 (2005): 1238-1248.
[8] Halliday, NL; Tomasek, JJ (March 1995). "Mechanical properties of the extracellular matrix influence fibronectin fibril assembly in vitro.". Experimental Cell Research. 217 (1): 109–17.
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Line 81:
Line 69:
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[10] Sundararaghavan, Harini G., Shirley N. Masand, and David I. Shreiber. "Microfluidic generation of haptotactic gradients through 3D collagen gels for enhanced neurite growth." Journal of neurotrauma 28.11 (2011): 2377-2387.
[10] Plotnikov, SV; Pasapera, AM; Sabass, B; Waterman, CM (21 December 2012). "Force fluctuations within focal adhesions mediate ECM-rigidity sensing to guide directed cell migration.". Cell. 151 (7): 1513–27.
----
[11] Carter, Stephen B. "Haptotaxis and the mechanism of cell motility." Nature 213 (1967): 256-260.
----
[12] Murphy-Ullrich, Joanne E. "The de-adhesive activity of matricellular proteins: is intermediate cell adhesion an adaptive state?." The Journal of clinical investigation 107.7 (2001): 785-790.
----
[13]Baum, Jake, et al. "A conserved molecular motor drives cell invasion and gliding motility across malaria life cycle stages and other apicomplexan parasites." Journal of Biological Chemistry 281.8 (2006): 5197-5208.
----
[14]Grayson, Warren L., et al. "Engineering custom-designed osteochondral tissue grafts." Trends in biotechnology 26.4 (2008): 181-189.
== History ==
▪1880s: First studies of chemotaxis (Engleman)
----
▪1892: Ramón y Cajal predicted axons navigate in response to gradients of cues
----
▪1914: Substrate is important to migration (Harrison)
----
▪1934: Contact guidance – migration directed by substrate topology during embryonic development (Weiss)
Today: Debate among scientists about the differences between Haptotaxis and Chemotaxis; applications of cellular process
== Motivation ==
Because this cellular process is important in the immune response, development and wound healing, it is an attractive candidate for exploitation in regenerative medicine. [3] For these reasons, there have been a surge of research in the attempt at creating cellular gradients to direct the process of tissue development [3, 4, 5, 6, 7, 8, 9] .
== Stem Cell Differentiation ==
There have been several different developments among researchers in the use of Haptotaxis and its properties in tissue engineering and regenerative medicine efforts. Notably, the use of stem cells seeded certain grafts to induce tissue and differentiation proliferation [5] In these studies, there is an overarching goal to create tissue derived from human cells to be incorporated in vivo. These studies can affect a vast range of people, including those who with bone deficiencies and tissue deformations and/or deficiencies. [5].
As an example, there has been development in the creation of a human mesenchymal stem cell (hMSC) seeded polymer bone grafts. The grafts are designed to be porous to allow access to certain growth factors. In doing so, a chemical gradient is created, in which draws certain cells to certain areas to proliferate and differentiate. Further, stiff, rod-like fibers are incorporated into the graft to act as guides for the cell. By doing so, the hMSCs can differentiate into osteoblasts, allowing for incorporation in vivo [7].
== Microfluids to create chemical gradients ==
There has also been work in using microfluids in the creation of a chemical gradient to exploit Haptotaxic properties [10]. By the creation of a gradient, cellular migration - along with differentiation and proliferation - can be studied and exploited in the use of regenerative medicine and tissue engineering.
As an example, one group varied adhesive ligands through a 3D collagen gel to create a Haptotaxis gradient. By planting a chick embryo dorsal root ganglion into the scaffold, the growth of neural cells was measured. The results suggested that the incorporation of gradients improved regeneration of axons -- suggesting the growth of neural tissue.
== Haptotaxis in Cancer ==
Interestingly, tumor cells possess strong Haptotaxis properties. Tumor cells use the properties of Haptotaxis to metastasize and spread, furthering their effects on the body. Though not much is known about the process, it has been hypothesized that vibronectin, a glycoprotein of which promotes cellular spreading, helps create a gradient of which assists tumor cells mestastize. [4] However, work in understanding the process of cellular migration through Haptotaxis could lead to a greater understanding of cancer metastasis.
== Conclusions ==
Work in tissue engineering and regenerative medicine by using Haptotaxis as a vehicle to create specific tissue regeneration is promising. With many different types of biocompatible grafts and the use of stem cell differentiation, and with promising results, it would seem in vivo generation of tissue might happen. However, there are pitfalls to this approach - first of which, specific stem cell differentiation is difficult and can often lead to different desired products. Further, the creation and maintenance of a chemical gradient is difficult in vivo. Additionally, the 3D microenvironment is incredibly influential to the properties of Haptotaxis and can be difficult to replicate [6]. However, technology is advancing in the creation of 3D hydrogels. Lastly, the use of people’s cells is expensive and difficult to procure.
== References ==
[1] Lo, Chun-Min, et al. "Cell movement is guided by the rigidity of the substrate." Biophysical journal 79.1 (2000): 144-152.
----
[2]Friedl, Peter, and Bettina Weigelin. "Interstitial leukocyte migration and immune function." Nature immunology 9.9 (2008): 960-969.
----
[3]Basan, Markus, et al. "Alignment of cellular motility forces with tissue flow as a mechanism for efficient wound healing." Proceedings of the National Academy of Sciences 110.7 (2013): 2452-2459.
----
[4]Basara, Michael L., et al. "Stimulation of haptotaxis and migration of tumor cells by serum spreading factor." Cancer research 45.6 (1985): 2487-2494.
----
[5]Ricoult, Sébastien G., Timothy E. Kennedy, and David Juncker. "Substrate-bound protein gradients to study haptotaxis." Frontiers in bioengineering and biotechnology 3 (2014): 40-40.
----
[6]Subramony, Siddarth D., et al. "The guidance of stem cell differentiation by substrate alignment and mechanical stimulation." Biomaterials 34.8 (2013): 1942-1953.
----
[7]Chen Jianbo, Paetzell, Emily, Zhou, Jikou, Lyons, Lauren, & Soboyejo, Wole (Jun 2010). Osteoblast-like cell ingrowth, adhesion and proliferation on porous Ti-6Al-4V with particulate and fiber scaffolds. Materials Science and Engineering C, Biomimetic Materials, Sensors and Systems, 30(5), 647-656. doi:101016/jmsec201001005
----
[8] Holtorf, Heidi L., et al. "Flow perfusion culture of marrow stromal cells seeded on porous biphasic calcium phosphate ceramics." Annals of biomedical engineering 33.9 (2005): 1238-1248.
----
[9]DiMilla, Paul A., et al. "Maximal migration of human smooth muscle cells on fibronectin and type IV collagen occurs at an intermediate attachment strength." The Journal of cell biology 122.3 (1993): 729-737.
----
[10] Sundararaghavan, Harini G., Shirley N. Masand, and David I. Shreiber. "Microfluidic generation of haptotactic gradients through 3D collagen gels for enhanced neurite growth." Journal of neurotrauma 28.11 (2011): 2377-2387.
----
[11] Carter, Stephen B. "Haptotaxis and the mechanism of cell motility." Nature 213 (1967): 256-260.
----
[12] Murphy-Ullrich, Joanne E. "The de-adhesive activity of matricellular proteins: is intermediate cell adhesion an adaptive state?." The Journal of clinical investigation 107.7 (2001): 785-790.
----
[13]Baum, Jake, et al. "A conserved molecular motor drives cell invasion and gliding motility across malaria life cycle stages and other apicomplexan parasites." Journal of Biological Chemistry 281.8 (2006): 5197-5208.
----
[14]Grayson, Warren L., et al. "Engineering custom-designed osteochondral tissue grafts." Trends in biotechnology 26.4 (2008): 181-189.
Durotaxis is the migration of cells based on the structural gradients of the rigidity of the substrate (referring to ECM, bone, or any scaffold construct)(figure1).The elastic modulus is used to measure the stiffness of the substrate which changes with each cell type.[1] The cells typically migrate in the direction of higher stiffness (figure 2).[2] The rigidity of the substrate is known to affect migration, immunology, morphology, motility, and various other processes due to the interactions between the extracellular matrix and the cytoskeleton.[1](figure 3)
The stiffness of the substrate allows cells to generate forces using focal actin-myosin complexes onto the the substrate. These forces produce focal adhesion kinases which controls the overall structure of the cytoskeleton. The cytoskeleton is highly dependent on the stiffness of the substrate which is important because the cytoskeleton determines the morphology of the cell as well as the chemical responses in the signaling pathways. Controlling the stiffness is therefore key in generating the type of cell that is needed.[3]
Figure 2 shows the elongation that is experienced by the cells when they sense stiffness
Figure 2.Elongation[2]
Figure 3 shows the affects of different cellular cross linkages on migration. ]
History
▪1892: Ramón y Cajal predicted axons navigate in response to gradients of cues
▪1914: Migration occurs due to the substrate in the microenvironment (Harrison)
▪1934: Contact guidance – migration directed by substrate topology during embryonic development (Weiss)
▪1990's: Cytoskeletal stiffness, morphology, motility, and fibronectin fibril assembly was proven to influence migration
▪ 20th century: It was discovered that cells could detect and respond to substrate stiffness
Motivation
Understanding how to stimulate or inhibit the migration of cells is crucial for cellular regeneration and treatment. The medical field is driving the need for this research to potentially solve problems like host rejection makes durotaxis in engineering a hot topic.
Bone Scaffolds
For years, doctors have been using allograft bone transplants and other replacement methods that are cost inefficient, cause inflammation, extensive pain, and are prone to rejection or replacement after so many years of use. Recent studies in the mechanical properties of bone have produced a bone scaffold that has similar rigidity and porosity to real bone and would allow for the integration of cells completely in less than four weeks. This is possible because the scaffold mimics the stiffness of the mesenchymal stem cells. As said before, the mimicry of the rigidity of the ECM allows for the bound stem cells to create focal adhesion forces which give the the cytoskeletal organization. The organization of the of the cytoskeleton is what gives the cells their shape and thus function.[4][5][6]
Durotaxis in Cancer
Cancer cells use durotaxis extensively affecting the lives of more than 200,000 people every year. One of the key properties that enable cancer to succeed is its stiffness. Tumors can be found to be as much as 10 times stiffer than the normal breast tissue this dramatic gradient causes the pull of endothelial cells to its mass allowing for tumor growth and for metastasis. [4] By finding ways to counteract these properties doctors could slow down the progression of cancer and make treatment more successful.
Conclusions
Tissue engineering and regenerative medicine have recently been found to be greatly affected by the durotaxic properties of the ECM. Engineers have been able to use the information that they have recently discovered to make huge advances in cancer research and bone replacement with more improvements guaranteed to come. Hopefully scientists will be able to answer more questions using the research they find with gradient hydrogels and experimentation.
References
[1] Ulrich, Theresa A., Elena M. de Juan Pardo, and Sanjay Kumar. “The Mechanical Rigidity of the Extracellular Matrix Regulates the Structure, Motility, and Proliferation of Glioma Cells.” Cancer research 69.10 (2009): 4167–4174.
[2]Friedl, Peter, and Bettina Weigelin. "Interstitial leukocyte migration and immune function." Nature immunology 9.9 (2008): 960-969.
[3]Sant, Shilpa et al. “BIOMIMETIC GRADIENT HYDROGELS FOR TISSUE ENGINEERING.” The Canadian journal of chemical engineering 88.6 (2010): 899–911.
[4]Breuls, Roel G.M, Timothy U Jiya, and Theo H Smit. “Scaffold Stiffness Influences Cell Behavior: Opportunities for Skeletal Tissue Engineering.” The Open Orthopaedics Journal 2 (2008): 103–109.
[5]Quintero, Andres J, et al. “Stem Cells for the Treatment of Skeletal Muscle Injury.” Clinics in sports medicine 28.1 (2009): 1–11. PMC. Web. 21 Mar. 2017.
[6]Isenberg, Brett C. et al. “Vascular Smooth Muscle Cell Durotaxis Depends on Substrate Stiffness Gradient Strength.” Biophysical Journal 97.5 (2009): 1313–1322. PMC.
[7]Wang, N; Butler, JP; Ingber, DE (21 May 1993). "Mechanotransduction across the cell surface and through the cytoskeleton.". Science. 260 (5111): 1124–7.
[8] Halliday, NL; Tomasek, JJ (March 1995). "Mechanical properties of the extracellular matrix influence fibronectin fibril assembly in vitro.". Experimental Cell Research. 217 (1): 109–17.
[9]DiMilla, Paul A., et al. "Maximal migration of human smooth muscle cells on fibronectin and type IV collagen occurs at an intermediate attachment strength." The Journal of cell biology 122.3 (1993): 729-737.
[10] Plotnikov, SV; Pasapera, AM; Sabass, B; Waterman, CM (21 December 2012). "Force fluctuations within focal adhesions mediate ECM-rigidity sensing to guide directed cell migration.". Cell. 151 (7): 1513–27.
![Figure 3.Cellular migration using different scaffolds [3]](/wiki/File:Cellmigration.jpg)
]
