In an article from a couple of years ago, Zimmerman et al (Mol Genet Metab. 2013 Aug;109(4):345-53) discuss evidence for improvement of biochemical measures with adipose transplant in 2 mouse models of maple syrup urine disease (MSUD).
This brings up the very interesting question about which soft tissues provide adequate enzymatic activity for therapeutic replacement potential. This could be either an adjunctive therapy to improve general control in a condition such as MSUD, or potentially a long term single therapy depending on the restoration of metabolic control.
Hilary Vernon, MD PhD