news @ nature.com�-�Human stem cells trigger immune attack�-�Doubt cast on therapeutic use of embryonic cell lines. If my theory of Cell Recognition Factors is correct, this immune attack is happening for reasons besides the assimilation of foreign molecules into lab-grown cells. Remember that an embryonic cell when growing in utero expresses a different set of RF's. This enables the placenta to wall it off from maternal attack. If it had RF's the same as that of the mother, the embryo would invade the maternal tissues just like a cancer does. A prediction of this theory is that stem cell implantation would not work unless matched for RF's.
Now, as humans, we all have the same set of RF's but only a subset is expressed. The question that needs to be answered is this: what is the basis for selecting one subset over another? Is it random or is it selected based on RF's already present in the embryonic cell's early environment. Either way, the developing embryo's objective is to express a different set of RF's but if it is controlled we have a chance of directing it so that it expresses RF's that are compatible with the intended host. If it is random or based on some queue, I do not see an easy solution at this time.
Now, as humans, we all have the same set of RF's but only a subset is expressed. The question that needs to be answered is this: what is the basis for selecting one subset over another? Is it random or is it selected based on RF's already present in the embryonic cell's early environment. Either way, the developing embryo's objective is to express a different set of RF's but if it is controlled we have a chance of directing it so that it expresses RF's that are compatible with the intended host. If it is random or based on some queue, I do not see an easy solution at this time.
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