Fig. 2.

Cell stiffness and relative nuclear fluctuation correlate with potency of putative MSCs. Thresholds of effective mean elastic modulus E and average nuclear fluctuations NF were determined experimentally by comparing these mechanical properties of all donor subpopulations sampled against the in vitro multilineage differentiation potential. Multipotent MSC subpopulations exhibited a consistent biophysical phenotype: sufficiently low cell diameter (50), low mechanical stiffness (E^lo), and high relative nuclear fluctuation (NF^hi) (color-coded green). In contrast, subpopulations that did not meet this criterion (i.e., those that were either large or of high mechanical stiffness or of low relative nuclear fluctuation) were only bipotent (color-coded red). (A) Large or D^hi MSCs from all adult donors were bipotent and exhibited an average E >375 Pa. (B) Similarly, small or D^lo MSCs of E > 375 Pa (aD4 and fD4) were also bipotent. In contrast, multipotent D^lo MSCs were consistently more compliant with E < 375 Pa. (C) D^hi MSCs from all adult donors exhibited an average NF of <1.2%, which is in contrast to the (D) multipotent D^lo MSCs that typically exhibited NF > 1.2%. Notably, D^lo MSCs that were bipotent (aD5 and fD5) also exhibited NF <1.2%, suggesting that among the many biophysical parameters considered herein, multipotency is characterized minimally by three biophysical criteria (D^loE^loNF^hi).