Differentiation-related changes in mitochondrial properties as indicators of stem cell competence.
Several methods may be used to assess stem cell competence, including the expression of cell surface markers and telomerase activity. We hypothesized that mitochondrial characteristics might be an additional and reliable way to verify stem cell competence. In a multipotent, adult monkey stromal stem cell line, previously shown to differentiate into adipocytes, chondrocytes, and osteocytes, we found that several mitochondrial properties change with increasing passage number in culture. Cells from the earliest passage (P11) versus those from a later passage (P17) are characterized by: (a) a much higher percentage of cells (85% vs. 18%) with a perinuclear arrangement of mitochondria; (b) a much lower percentage of cells (1% vs. 57%) with an aggregated mitochondrial arrangement, in which mitochondria appear to coalesce into large clumps; (c) a much lower percentage of cells with lipid droplets (1% vs. 36%), suggesting less differentiation into adipocytes; (d) a 5.6-fold lower ATP content per cell (0.45 vs. 2.51 pmoles ATP/cell; and (e) a 10-fold higher rate of oxygen consumption (37.8 vs. 3.8 nmoles O2/min/10(3) cells), indicating a higher metabolic activity. Collectively, these data indicate that the perinuclear arrangement of mitochondria, accompanied by a low ATP/cell content and a high rate of oxygen consumption, may be valid indicators of stem cell differentiation competence, while departures from this profile indicate that cells are differentiating or perhaps becoming senescent. These results represent the first characterization of mitochondrial properties reported for a primate stem cell line.
Department of Biological Sciences, University of New Orleans, New Orleans, Louisiana 70148, USA. tlonerga@uno.edu
Thomas
T
Lonergan
Carol
C
Brenner
Barry
B
Bavister
D000255:Adenosine Triphosphate / Q000032:analysis; D017667:Adipocytes / Q000166:cytology / Q000502:physiology; D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D002460:Cell Line; D008253:Macaca mulatta; D008297:Male; D008565:Membrane Proteins / Q000032:analysis / Q000502:physiology; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000502:physiology* / Q000648:ultrastructure; D039902:Multipotent Stem Cells / Q000737:chemistry / Q000166:cytology / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology; D017154:Stromal Cells / Q000737:chemistry / Q000166:cytology / Q000502:physiology*; D019098:Telomerase / Q000032:analysis / Q000502:physiology
D008565:Membrane Proteins; D000255:Adenosine Triphosphate; D019098:Telomerase