Introduction
During brainstorming, we discussed a lot of different problems. We came across the problems of tissue-engineering where you need a three dimensional matrix for the cells to attach. Since the origin of these matrices is always a problem and can cause immunogenicity, new solutions are needed.
When thinking more about this problem we thought of a different approach on building three dimensional structures. What if we could just print tissue, bones or other stuff? How could we do that?
One of us had the idea to try something like the engraving of glassblocks from the inside with bacteria. There you can print a picture inside glass with laser. How can we activate our bacteria with laser, so that they express a protein?
There we could use optogenetics which provides an elegant way of converting a light signal in proteinexpression. Optogenetics was chosen Method of the Year 2010 by Nature Methods and is titled as one of the breakthroughs of the decade. The hallmark of optogenetics is introduction of fast light-activated channels and enzymes that allow temporally precise manipulation of electrical and biochemical events in bacteria. One can use channels derived from bacteriarhodopsin, photosynthesis associated complexes, like phycobilines in algae (for our red light sensor) or use existing light sensory domains already in e.coli (like our blue light promoter).
When thinking more carefully about the idea, we knew that we would need to immobilize the bacteria somehow to make sure that we can target certain spots. For this reason we have chosen a matrix named gelrite which can be penetrated by light with only little scattering and which contains a minimum of nutrient to enable growth and proteinexpression.
With the chosen method it was suitable to use two different wavelengths to activate our bacteria. Only when a bacterium is hit by both wavelengths it should express a protein, e.g. a coloured molecule, to generate a three dimensional picture inside the agar block. The AND-Gate developed from last years team … and the Voigt lab in … provided the solution.
This logical gate is based on amber stop-codon suppression via the non-canonical tRNA supD. A light sensitive promoter induces the expression of mRNA with a stop-codon suppression coding for a T7-polymerase, which can only be translated by ribosomes if the correct amber tRNA is present. The tRNA is expressed by a second light-sensitive promoter. Only if both signals are present, the expression of a protein under the control of a T7-promoter can start. We chose blue and red light promoter (also developed by former igem teams) because their wavelengths lie wide apart. With this we should be able to target activation of expression in desired spots.
Since easy artificial production of human tissue and bones is still a difficult task it would be great to make this task attractive for biotechnology. This would be more biocompatible and there would be less immunrejection because the material doesn’t show the surface antigens of other mammalian material. After the forming of bone, all left over bacteria could be destroyed and the bone could be coated with cells of the recipient.
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Introduction
During brainstorming, we discussed a lot of different problems. We came across the problems of tissue-engineering where you need a three dimensional matrix for the cells to attach. Since the origin of these matrices is always a problem and can cause immunogenicity, new solutions are needed.
When thinking more about this problem we thought of a different approach on building three dimensional structures. What if we could just print tissue, bones or other stuff? How could we do that?
One of us had the idea to try something like the engraving of glassblocks from the inside with bacteria. There you can print a picture inside glass with laser. How can we activate our bacteria with laser, so that they express a protein?
There we could use optogenetics which provides an elegant way of converting a light signal in proteinexpression. Optogenetics was chosen Method of the Year 2010 by Nature Methods and is titled as one of the breakthroughs of the decade. The hallmark of optogenetics is introduction of fast light-activated channels and enzymes that allow temporally precise manipulation of electrical and biochemical events in bacteria. One can use channels derived from bacteriarhodopsin, photosynthesis associated complexes, like phycobilines in algae (for our red light sensor) or use existing light sensory domains already in e.coli (like our blue light promoter).
When thinking more carefully about the idea, we knew that we would need to immobilize the bacteria somehow to make sure that we can target certain spots. For this reason we have chosen a matrix named gelrite which can be penetrated by light with only little scattering and which contains a minimum of nutrient to enable growth and proteinexpression.
With the chosen method it was suitable to use two different wavelengths to activate our bacteria. Only when a bacterium is hit by both wavelengths it should express a protein, e.g. a coloured molecule, to generate a three dimensional picture inside the agar block. The AND-Gate developed from last years team … and the Voigt lab in … provided the solution.
This logical gate is based on amber stop-codon suppression via the non-canonical tRNA supD. A light sensitive promoter induces the expression of mRNA with a stop-codon suppression coding for a T7-polymerase, which can only be translated by ribosomes if the correct amber tRNA is present. The tRNA is expressed by a second light-sensitive promoter. Only if both signals are present, the expression of a protein under the control of a T7-promoter can start. We chose blue and red light promoter (also developed by former igem teams) because their wavelengths lie wide apart. With this we should be able to target activation of expression in desired spots.
Since easy artificial production of human tissue and bones is still a difficult task it would be great to make this task attractive for biotechnology. This would be more biocompatible and there would be less immunrejection because the material doesn’t show the surface antigens of other mammalian material. After the forming of bone, all left over bacteria could be destroyed and the bone could be coated with cells of the recipient.