The Effect of Estrogen on Bone Marrow-Derived Rat Mesenchymal Stem Cell Maintenance: Inhibiting Apoptosis Through the Expression of Bcl-xL and Bcl-2

Abstract

Mesenchymal Stem Cells (MSCs) have high therapeutic value for regenerative medicine and tissue engineering due to their differentiation potential and nonimmunogenic characteristics. They are also considered as an effective in vivo delivery agent because of their ability to migrate to the site of injury. A major roadblock in their use for cell-based therapies is their rareness in vivo. Therefore, it is important to obtain increased number of functional MSCs in vitro in order to have adequate numbers for therapeutic regiments. We aimed to investigate the role of estrogen and its mechanism in obtaining more MSCs. MSCs were isolated from female and ovariectomized rats and cultured in the presence and absence of 10 −7 M estrogen. In the presence of estrogen, not only their CFU-F activity increased but also apoptotic rate decreased as shown by TUNEL staining leading to obtain more MSCs. Also the number of the cells in the colonies increased upon estrogen treatment. To reveal the mechanism of this effect, we focused on Bcl-2 family of proteins. Our immunoblotting experiments combined with knockdown studies suggested a critical role for anti-apoptotic Bcl-x L and Bcl-2. Estrogen treatment up regulated the expression Bcl-x L and Bcl-2. When we knocked down the expression of bcl-x L and bcl-2, MSCs lacking these genes showed an increase in the apoptotic rate in contrast to normal MSCs following estrogen treatment. Therefore, estrogen treatment will be of great advantage for cell-based therapies in order to get more functional MSCs and may provide opportunities to develop new strategies for debilitating diseases.

Ovariectomized Rats with Established Osteopenia have Diminished Mesenchymal Stem Cells in the Bone Marrow and Impaired Homing, Osteoinduction and Bone Regeneration at the Fracture Site

“…Although, E2 is not a recommended treatment for fracture healing, a recent study showed improvement in fracture healing based on histological and biomechanical parameters in Ovx rats treated with E2, thus suggesting a positive role of the hormone in promoting fracture healing [43]. However, the reported study used a prophylactic design where E2 treatment was given to rats soon after Ovx without allowing the time for osteopenia to develop.…”

“…Reduced MSC population in the Ovx rats could be due to apoptosis as E2 at a pharmacological concentration (10 −7 M) has been shown to exert anti-apoptotic/prosurvival effect on MSC in vitro [43]. In postmenopausal women, osteoporosis delays fracture healing and causes reduced bone deposition [44], and together, the recovery of functional competence of the fractured bone in osteoporotic women is delayed [22].…”

Estrogen Receptor α and β in Mouse: Adipose-Derived Stem Cell Proliferation, Migration, and Brown Adipogenesis In Vitro

“…ASCs and BMSCs share common characteristics, including growth and morphology [31], displaying fibroblastic features, and a similar transcriptional and cell surface marker expression profile [32]. At present, much of the research is mainly focusing on the effects and mechanisms of estrogen and its receptors for improving BMSC behavior in tissue engineering applications [33]. Although an ideal cell type for transplantation due to availability of convenient methods and their presence in large cell quantities, ASCs still remain elusive with respect to effects mediated by estrogen receptor α and β.…”

Characterization of Bone-Marrow-Derived Stem Cells in Osteoporotic Models of the Rat

“…Due to this differentiation potential combined with their nonimmunogenic characteristics, MSCs are promising therapeutic tools in regenerative medicine 2 ISRN Stem Cells and tissue engineering [6][7][8][9] and thus also for therapeutic strategies in osteoporotic patients.…”