It turns out, a great deal!
These are not your grandad’s pond’s “big” koi.
These goldfish are truly enormous, weighing up to four-six pounds each (see photo at left from UC Davis and pic at right from the California Department of Fish and Wildlife)). Of course goldfish are not native to Lake Tahoe but they grow to great size there.
How does a goldfish get to be a five-pounder or even bigger?
Of course not just by spacious surroundings, but also by eating tons of smaller, mostly native fish. As a result the giant goldfish of Lake Tahoe are invasive, destructive creatures. At some point they likely reach a size for which they few if any natural predators in Lake Tahoe as is the case for many invasive species in their new homes.
As much as giant goldfish look really cool and their size is impressive, they presumably do significant harm to the natural ecosystem.
What can giant invasive goldfish teach us about stem cell treatments?
An exploding trend in the dubious stem cell clinic world is to move stem cells around the body, transplanting them almost willy nilly from place to place and person to person. We are not talking about one or two “pet” stem cells, but rather billions of cells too, often injected IV into the bloodstream.
By analogy I consider such cells to have the potential to be invasive species.
Stem cells are alive and can literally move around the body. They can and do grow at expense of surrounding “native” cells.
The field knows very little about what happens to stem cells introduced into non-native parts of the body, but it is not difficult to see how they might do great harm at the expense of surrounding cells and to the native “ecosystem” (i.e. in this case the body of the human patient). Some transplanted stem cells may also have no “predators” (i.e. immune cells that target them) given possible immunoprivilege or an autologous setting.