Treatment will depend on whether she has been diagnosed as moderate, severe or very severe AA. This is based on both marrow cellularity and blood counts, not just one or the other. If it is moderate (MAA), the usual approach is just watch and wait.
If it is SAA or VSAA, the protocol generally goes as follows: if she is under 40 years of age
and has an HLA matched sibling, then bone marrow transplant would be the recommended first line of treatment. If she does not have a sibling match,
or if she is over 40, then the usual approach is to try immunosuppresant therapy (IST). If that doesn't work, then a transplant with an unrelated donor may be the next option to explore.
There are some other options as well. High dose cytoxan and various monoclonal antibodies are currently being explored, but still considered comparatively experimental. They may involve either going to a specific center or being enrolled in a clinical trial. Currently the ATG/cyclosporine (IST) protocol is considered to be the standard, and the most widely practiced.
ATG/cyclo doesn't actually grow marrow so much as it knocks out the autoimmune attack that is thought to be short-circuiting proper marrow function. By killing off the attacking T-lymphocytes, the marrow is given a chance to recover on its own. This can be a very slow and sometimes incomplete process, and of course immune suppression is not without risk.
ATG is not chemotherapy, but chemo is a part of the transplant process (or in the case of high-dose cytoxan, used on its own without transplant).
I suggest you send for the AA&MDSIF's informational booklet on AA, or read the overview on their website:
http://www.aamds.org/about/aplastic-anemia/diagnosis
You can also find a lot of more specific information reading through some of the threads on this forum.
Hope this helps, and good luck to your friend!