Table 1.

Incidental or deliberate DNA damage abrogates ES cell reprogramming potential.

ES cells: DNA damage:	Control No	Rad21 ko (24h) No
ES cell #	100×106	100×106
Somatic cell #	100×106	100×106
Heterokaryon #	∼6×106*	∼6×106*
Reprogramming	++	+++
ES cells: DNA damage:	Control No	Rad 21 ko (48h) Incidental	Doxorubicin Deliberate
ES cell #	25×106	25×106	25×106
Somatic cell #	25×106	25×106	25×106
Heterokaryon #	∼1.5×106*	None	None
Reprogramming	++	N/A	N/A

^*Estimate based on 3% fusion efficiency determined by flow cytometry

Acutely cohesin-depleted ES cells not only retained the ability to reprogram somatic cells in heterokaryons but in addition showed an unexpected increase in their reprogramming potential (top, n = 3 biological replicates, 100 × 10⁶ ES cells per fusion). ⁴¹ Fusion with Rad21 KO (48h) ES cells and doxorubicin-treated (6h) ES cells did not result in viable heterokaryon formation or reprogramming. Poor survival meant that lower ES cell numbers were available (25 × 10⁶), and control ES cell numbers were reduced accordingly (bottom, n=2 biological replicates per treatment condition).