[ExI] Fame meat

[Bryan Bishop]

On Tuesday 22 April 2008, James Clement wrote:
> In Vitro Meat Production-Contest Rules
> People for the Ethical Treatment of Animals (PETA) aims with this
> contest to encourage the development and offering for sale of in vitro
> chicken meat in commercially significant quantities. A prize of
> $1,000,000 is offered to the first successful individual, group, or 
> company to do so. To receive the $1 million prize, the successful 
> candidate must be the first to do both of the following:   

Screw the 'you have to make a profit' bullshit, let's just do it. So, I 
guess we'd want to start with myogenic regulatory factors like MyoD, 
MEF2, herculin and myogenin, that's a good place to start *after* 
TFs ;). To my recollection this is the MyoD-family of gen-reg networks 
in differentiation mostly occuring during embryogenesis from stem cells 
(so plug in the Yamanaka research here - there was a public lecture on 
IRC a few weeks ago on this, I mentiond the general steps involved in 
extracting skin cells and turning them into stem cells, more or less). 
These TFs and 'regulons' can be synthetically expressed in our 
bacterial circuits, so scaling up their production is a no brainer. The 
big problem is controlling development and making sure we can get 
enough payoff per few centimeters of tissue or something. For example, 

Muscle LIM protein promotes myogenesis by enhancing MyoD.
http://www.pubmedcentral.nih.gov.ezproxy.lib.utexas.edu/articlerender.fcgi?rendertype=abstract&artid=232327
> The muscle LIM protein (MLP) is a muscle-specific LIM-only factor
> that exhibits a dual subcellular localization, being present in both
> the nucleus and in the cytoplasm. Overexpression of MLP in C2C12
> myoblasts enhances skeletal myogenesis, whereas inhibition of MLP
> activity blocks terminal differentiation. Thus, MLP functions as a
> positive developmental regulator, although the mechanism through
> which MLP promotes terminal differentiation events remains unknown.
> While examining the distinct roles associated with the nuclear and
> cytoplasmic forms of MLP, we found that nuclear MLP functions through
> a physical interaction with the muscle basic helix-loop-helix (bHLH)
> transcription factors MyoD, MRF4, and myogenin. This interaction is
> highly specific since MLP does not associate with nonmuscle bHLH
> proteins E12 or E47 or with the myocyte enhancer factor-2 (MEF2)
> protein, which acts cooperatively with the myogenic bHLH proteins to
> promote myogenesis. The first LIM motif in MLP and the highly
> conserved bHLH region of MyoD are responsible for mediating the
> association between these muscle-specific factors. MLP also interacts
> with MyoD-E47 heterodimers, leading to an increase in the DNA-binding
> activity associated with this active bHLH complex. Although MLP lacks
> a functional transcription activation domain, we propose that it
> serves as a cofactor for the myogenic bHLH proteins by increasing
> their interaction with specific DNA regulatory elements. Thus, the
> functional complex of MLP-MyoD-E protein reveals a novel mechanism
> for both initiating and maintaining the myogenic program and suggests
> a global strategy for how LIM-only proteins may control a variety of
> developmental pathways.

MEF2: a transcriptional target for signaling pathways controlling 
skeletal muscle growth and differentiation
> Skeletal muscle development involves a multistep pathway in which
> mesodermal precursor cells are selected, in response to inductive
> cues, to form myoblasts that later withdraw from the cell cycle and
> differentiate. The transcriptional circuitry controlling muscle
> differentiation is intimately linked to the cell cycle machinery,
> such that muscle differentiation genes do not become transcribed
> until myoblasts have exited the cell cycle. Members of the MyoD and
> MEF2 families of transcription factors associate combinatorially to
> control myoblast specification, differentiation and proliferation.
> Recent studies have revealed multiple signaling systems that
> stimulate and inhibit myogenesis by altering MEF2 phosphorylation and
> its association with other transcriptional cofactors.

In vitro organ culturing protocols
http://www.protocol-online.org/prot/Cell_Biology/Cell_Culture/Organ_Culture/

> Signaling By Fibroblast Growth Factors: The Inside Story
> Mitchell Goldfarb
>
> Summary: Polypeptide growth factors bind to the extracellular domains
> of cell surface receptors, triggering activation of
> receptor-intrinsic or receptor-associated protein kinases. Although
> this central thesis is widely accepted, one family of proteins, the
> fibroblast growth factors (FGFs), have for more than a decade
> attracted a research "counterculture" looking for direct FGF actions
> inside cells. Goldfarb discusses how the search for alternative
> signaling pathways is moving mainstream with the help of two recent
> publications reporting specific intracellular targets for FGF and
> FGF-like proteins.

And this one seemed impressive: Multilineage differentiation of human 
mesenchymal stem cells in a three-dimensional nanofibrous scaffold. It 
is some simple engineering and doesn't actually know what the 
mechanisms were that allowed the cell cultures to diffuse over their 
nanofabrous surface, but they were able to produce tissue stains, but 
to what extent did this allow greater volume is suspect (and wasn't 
even their goal). Growing over artificial ECMs could be an interesting 
approach if the molecular approaches detailed above can be 
simultaneously tackled.

MEF2: a transcriptional target for signaling pathways controlling
skeletal muscle growth and differentiation (1999) <-- good review.

A few months ago a particularly prominent researcher did a press release 
on her heart-in-a-jar research, she has this beating heart that you can 
actually hold, and it is wired up to their system for the circulation 
of a (small!) blood supply hooked up to the oxygen machines etc. But 
there's been lots of funding for cardiac research, methinks. 

Anyway, here's a list of strategies that I have been considering:
* one slice at a time
* total muscle-organ growth
* ECMs, scaffolds, biocompatible glues, 
** especially 3D scaffolds with small micropumps for nutrients
*** artificial vascularization
* cellular printers (the 3D printers)
* submersive nutrient tanks of just the right mix of connective + muscle

The main thing to worry about is the volume of meat produced. In many of 
these situations, researchers have previously optimized for 2D surface 
area since that gives the best access to the cells, but for volume? Not 
the same thing.

I dumped some notes over at:
http://heybryan.org/mediawiki/index.php/Meat_on_a_stick

Anybody want to help out?

- Bryan
________________________________________
http://heybryan.org/