This is a very complicated issue about which Christians can legitimately and justly disagree with one another.
As for me: I think stem cell research is quite problematic, due to the origin and source of stem cells. The more these cells are used for research, the higher the demand for these cells will be, and the method of getting these cells (which is ethically dubious on a number of levels) would be increased.
As for cloning (and genetic alteration in general) I think it is okay *but within carefully watched limits*. There are many unknowns involved, and harmful and painful mistakes will be made in trying to alter or clone different life forms. I don't think the 'possible' benefits can justify the nearly certain harms and pain.