Team:NYU Shanghai/Description

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Mechanical stimuli

What if we could simply apply the bass sound, and implanted stem cells are differentiated very quickly to regenerate tissue? It potentially simplifies the method of cell therapy and reduces the burden of patients during treatments.
Piezoelectric Scaffold

Piezoelectricity is the electric charge that is accumulated by the mechanical stress in solid materials. Thus, the solid material that can convert mechanical stress to the electric signal is very suitable for scaffolding cells to both support the structure of cells and stimulate signaling [2].
Electrochemical Modulators

The electric signals then need to alter the gene expression. So, electrochemical modulators such as ferrocyanide and pyocyanin are very important. Modulators respond to the electric charge by reduction-oxidation reactions.
Cells

Finally, the cells with transcription factors that can be either activated/inactivated by redox modulators. Since our design of the corresponding TFs for our parts prevail in the cytoplasm, it is easily and quickly tuned by the outer stimuli.
  
Introduction to tissue engineering

One of the definitions of tissue engineering is “an interdisciplinary field that applies the principles of engineering and the life sciences toward the development of biological substitutes that restore, maintain, or improve tissue function.” [1] Nowadays, as the field of stem cell research is being developed, the regenerative therapies of various human organs from one single stem cell are expected to cure many diseases that require a transplant of limited donations of organs.
Why we need a new scaffold

A scaffold is one of the three essentials in tissue engineering along with biological factors and stem cells. It aims at a three-dimensionally rigid structure to regenerate organs. It often mimics the extracellular matrix and helps cell migration and delivers growth factors or expressed biochemicals. Also, biodegradability is an important factor because it should preferably be absorbed without any surgical removal.
Our idea

To show that our idea is feasible in real medical use, our goal is to show that we can control the gene expression of a group of cells with spatial and temporal accuracy. After we confirm that we have enough piezoelectricity in fish scale-derived collagen, and our designed parts are manipulated by electrodes, we co-culture fish scale and transformed E. coli. in agar plates and apply mechanical stimuli continuously. The network we will build starts off from E. coli. derived electronic controlled gene parts and differentiate the character of cell populations by cell-to-cell communication [3].
What we plan to do

The first part of our project is to confirm that fish scale-derived collagen generates electricity. We buy a very common Chinese fish (草鱼), Ctenopharyngodon idellus, in the local supermarket. Once fish scales are collected, they are washed by sodium hydroxide and demineralized by EDTA. We are to duplicate this treatment by different time length to find the optimal procedure to gain the best electric potential out of fish scales. We confirm the treatment level by FT-IR and elemental analysis. The potentials of fish scales generated by tapping, bending, and other mechanical stimuli are measured. Moreover, fish scales will be fabricated with agar plate in order to co-culture with cells and potentials generated by indirect stimuli such as soundwaves are measured.
Second, cells that can be regulated by the electric potential is essential for our project to show our tissue engineering model. We found that E. coli. has a promoter (pSox) regulated by the redox modulators via its NADPH dependent enzymes [3], and the previous iGEM team (2018 Imperial College) have shown some interesting schemes of electrical control of gene expression by using that promoter. In this part, we are going to examine their electric-dependent genes and our own designed genes which does quorum sensing and cell-to-cell communication, under the constant voltage and necessary redox drugs. The primary parts of our own design are composed of two genes; N-Acyl homoserine lactone (AHL) producing genes with pSoxR promoter and LuxR bidirectional promoter with reporter genes which is regulated by AHL. Parts are transformed in separate cells and each strain will be silenced in their corresponding transcription factors so that cells’ response with different plasmids will be differentiated. E. coli. with those parts is tested on the agar plate which has electrodes to apply moderate voltage.
The final portion of our project is the integration of the first two parts. We will see how we can differentiate the gene expression by the electric potentials that are generated by fish scales. Initially, we plan fish scales to be fabricated in the agar plate, but we will take further steps to develop the novel tissue engineering techniques.
References

[1] Langer R, Vacanti JP (1993). "Tissue engineering". Science. 260 (5110): 920–6.
[2] Jacob J., More N., Kalia K., Kapusetti G. Piezoelectric smart biomaterials for bone and cartilage tissue engineering. Inflamm. Regen. 2018;38:2. doi: 10.1186/s41232-018-0059-8.
[3] T. Tschirhart, E. Kim, R. McKay, H. Ueda, H.C. Wu, A.E. Pottash, A. Zargar, A. Negrete, J.Shiloach, G.F. Payne, W.E. Bentley. Electronic control of gene expression and cell behavior in Escherichia coli through redox signaling. Nat Commun, 8 (2017), p. 14030