Most of the new items in 5.0 use item numbers too high for 4.4
4.4 (the EQ client actually) only allowed item numbers 1000-32532 and all the new items from the expansions are above that range. Plus they have additional features that 4.4 can't use.
Could some of the items be converted and used in 4.4...
: yea but it would be a pain, incomplete, and you would most likely end up overwriting other items to do so. :cry:
That said, if you want to it is possible.