You're right that we could already re-seed decellularized pig ECMs with human stem cells, but we have also already been able to derive stem cells from the stomach. I think the main claim that they're making is that by deriving both the ECM and the Stem cells from the patient, the resulting tissue engineering scaffold is less immunogenic than other methods.

While this is somewhat interesting, they get into trouble by going on to claim that they've been able to generate "functional cardiac, cortical, spinal cord, and adipogenic tissue implants". From what I can see in the paper they saw increased expression of a few markers associated with those cell types and some minor electrical activity, etc.

The idea that differentiating stem cells into vaguely tissue-like phenotypes is equivalent to being able to manufacture organs brings back memories of the shenanigans that went down at UCL a few years ago [1].

1. https://forbetterscience.com/2016/12/21/birchalls-trachea-tr...