Induction of osteoprogenitor cell differentiation in rat marrow stroma increases mitochondrial retention of rhodamine 123 in stromal cells

Abstract

Bone marrow stromal cells contain colony forming cells with the potential to differentiate into osteoprogenitor (OPC) cells. OPC-stimulation medium, containing dexamethasone, ascorbate, and beta-glycerophosphate is widely used to recruit OPCs in culture. Cultures were incubated 24 h with rhodamine 123 (Rho), on different days, to examine the effect of the OPC-stimulation medium on the mitochondrial membrane potential of stromal cells. Cultures grown in both ordinary medium (DMEM with 15% FCS) and OPC-stimulation medium showed 2 Rho retention peaks on days 3-4 and 10-11. Between days 5 and 10 there was a drop in Rho retention/cell. OPC-stimulation medium increased Rho retention by at least twice the amount relative to ordinary medium, and has quadrupled it on day 7. Incubation with Rho concentrations above 5.0 micrograms/ml inhibited the portion of increased Rho retention which was contributed by the OPC-stimulation medium. Prolonged exposure to 0.1, 1.0, and 10.0 micrograms/ml Rho for 12 days only slightly increased day 12 ALP activity/cell, had no effect on day-21 mineralization and only the high dose, 10.0 micrograms/ml, doubled stromal cell proliferation. Under 24 h incubation Rho concentrations of 1.0 microgram/ml and below can serve as a marker for mitochondrial membrane potential in differentiating stromal cells. The results indicate that under both culture conditions stromal cell mitochondria undergo cycles of high and low membrane potential states and that the OPC-stimulation medium constantly maintains an elevated membrane potential relative to ordinary medium.

Physical Shock Wave Mediates Membrane Hyperpolarization and Ras Activation for Osteogenesis in Human Bone Marrow Stromal Cells

“…A study with embryonic stem cells also showed that change of electrical fields could induce embryonic stem cell membrane potential change and cell differentiation (25). Similarly, studies with rat marrow cells also showed that change of membrane potential could induce osteoprogenitor cell differentiation (26). In contrast to growth factor induced membrane hypopolarization in PC12 cells (21), we demonstrated that SW treatment induced membrane hyperpolarization of bone marrow stromal cells.…”

A Delayed-early Response Nuclear Gene Encoding MRPL12, the Mitochondrial Homologue to the Bacterial Translational Regulator L7/L12 Protein

“…Although not essential for in vitro cell cultures (20), the mitochondrial activity is regulated at developmental and physiological levels (53,54), and its failure is probably involved in numerous degenerative diseases (55)(56)(57). Several nuclear genes activated by growth factors or hormones were shown to encode proteins controlling various aspects of mitochondrial metabolism: energy production (the adenine nucleotide translocator ANT2 (23), a proton/phosphate symporter (19), or cytochrome c (58)), lipid biosynthesis (the p90 glycerol-3-phosphate acyltransferase (59) or the uncoupling protein (60)), and protein import (the chaperonin hsp60 (61) or Fos effector protein-1, similar to a yeast mitochondrial protein import (22)).…”

Cell death in cultured human Saos2 osteoblasts exposed to low‐density lipoprotein

“…This process might start with temporary coupling of oxidative-phosphorylation, reflected by a surge in membrane potential, that is, subsequently discharged [Klein et al, 1996b] and being followed by mineralization. One effect of the DEX on the coupling period is its ability to increase the membrane potential [Klein et al, 1993a], this effect of DEX is associated (as seen in Fig. 9, 4 h time point) with a surge in Bax/Bcl-2 ratio.…”