how to grow a heart

a friend at work told me last week that scientists had cloned a heart.  i scoffed in disbelief.  i know fully well that if you want to grow a heart, you need to grow a whole other organism in order to coordiante all of the developmental triggers and events that are necessary for the proper formation of an organ.

today, i looked up the reference, and it appears that researchers have "generated" a new heart from an old one.  the key to this process is "decellularization" which i managed to get through three years of honours molecular biology without hearing about.  apparently, it is possible to remove all of the cells that constitute and organ, while keeping the "extracellular matrix" of the organ intact.  that's a little like... um... what's a good analogy...  taking all the cans out of one of those plastic-seagull-murdering-plastic-six-pack holders and being left with the holder.  the holder can then be used as a 3-dimensional template to guide the deposition and development of nascent tissues.

this sounds really promising and it's incredibly important research.  for decades, biologists have been wrestling with the questions of how, from an egg and a sperm, two cells can so perfectly, predictably and precisely divide millions and millions of times with just the right degree of differentiation to form something as impossibly complicated and miraculous as a cat... or even a human.  it was long believed (by me) that the only way that you would ever be able to "grow" a replacement part like a heart or a brain or a liver would be to grow an entire person... but this research seems to indicate that there might be alternatives. 

there are still huge obstacles to overcome.  the heart is a pretty simple thing (rather poetically) - it's essentially a giant mass of cardiac tissue that has to have a certain shape and potential for nerve conduction.  its cellular composition is contractile by design, so that it beats is no big deal to me.  compared to say, a kidney that has incredibly complex structure, chemical, ionic and hydrological gradients that have to be perfectly maintained, you can't just assemble a mass of kidney cells, even in the right shape, and expect it to work.  it's too intricately designed. in situ, developing organs are extremely-precisely exposed to very specific metabolic factors that guide the developing organism to activate and deactivate particular metabolic processes which allow it to take the required specialized form of skin, or blood vessel, or neuron, or glandular tissue, or bone.  tasks like growing limbs with different kinds of tissues are going to be much much harder to do even with some form of matrix. 

i owe my friend an apology for my disbelief, although i'm certainly not convinced that what these scientists have done is create a viable substitute heart, so much as made heart-cell slurry and then shaped it into a heart that then gels and reacts similarly to a real heart.  but if i had heart disease, that would still be music to my ears.

this decellularization technology is fascinating and makes for great dinner conversation, and believe me, this is an incredible medical milestone for mankind.  spare parts for humans?  can you see where this is going???

- g

song of the day for gaining eternal life: who wants to live forever, queen (watch this - it's breathtaking! freddie forever!!)