Nicotinamide overcomes pluripotency deficits and reprogramming barriers

Area of Science:

• Stem cell biology
• Cellular metabolism
• Epigenetics

Background:

• Intracellular signaling pathways are crucial for human pluripotent stem cell (hPSC) pluripotency.
• The role of NAD(+)-dependent pathways in hPSC pluripotency remains largely unexplored.

Purpose of the Study:

• To investigate the impact of NAD(+) levels on hPSC pluripotency and reprogramming.
• To determine the specific effects of NAD(+) precursors, nicotinamide (NAM) and nicotinic acid, on hPSC function.

Main Methods:

• NAD(+) depletion using FK866, a specific inhibitor of NAD(+) biosynthesis.
• Supplementation with NAD(+) and its precursors (NAM, nicotinic acid) to assess rescue effects.
• Evaluation of reprogramming efficiency, cell proliferation, apoptosis, senescence, and oxidative stress markers.
• Molecular analysis of key regulatory proteins (p53, p21, p16).

Main Results:

• NAD(+) depletion was detrimental to hPSCs, particularly during reprogramming and pluripotency maintenance.
• Both NAD(+) and its precursors replenished NAD(+) levels, but only NAM significantly improved reprogramming efficiency and kinetics.
• NAM enhanced hPSC maintenance by promoting proliferation and protecting against apoptosis, senescence, and oxidative stress.
• NAM's benefits were linked to the repression of p53, p21, and p16, especially at supra-physiological concentrations.

Conclusions:

• Adequate intracellular NAD(+) is essential for maintaining hPSC pluripotency.
• NAM offers distinct advantages beyond its role as a NAD(+) precursor, enhancing cellular stress resistance.
• NAM's effects on pluripotency involve metabolic and stress-protective mechanisms, impacting key cell cycle regulators.