The metastatic stem cell/cancer cell - the inspiration for drug delivery?

Stem cells and metastatic cancer cell-lines have been known to be able to colonize other tissues. Perhaps, this property might be worth considering in drug delivery, especially for biologic agents. It is possible to use one of these cells, and diminish any potential tumorigenic properties at the same time, introduce the gene to produce the biologic agent. The cell will then be able to metastasize to the target organ to produce its therapeutic effect. Okay, this sounds a little crazy. Back to daydream time!