Bisphosphonates Reduce Smoking-Induced Osteoporotic-Like Alterations by Regulating RANKL/OPG in an Osteoblast and Osteoclast Co-Culture Model.

Sheng Zhu,Bianca Braun,Tina Histing,Romina H Aspera-Werz,Andreas K Nussler,Tao Chen,Weidong Weng,Victor Häussling

doi:10.3390/ijms22010053

Abstract

Co-culture models have become mandatory for obtaining better insights into bone homeostasis, which relies on the balance between osteoblasts and osteoclasts. Cigarette smoking (CS) has been proven to increase the risk of osteoporosis; however, there is currently no proven treatment for osteoporosis in smokers excluding cessation. Bisphosphonates (BPs) are classical anti-osteoclastic drugs that are commonly used in examining the suitability of bone co-culture systems in vitro as well as to verify the response to osteoporotic stimuli. In the present study, we tested the effects of BPs on cigarette smoke extract (CSE)-affected cells in the co-culture of osteoblasts and osteoclasts. Our results showed that BPs were able to reduce CSE-induced osteoporotic alterations in the co-culture of osteoblasts and osteoclasts such as decreased matrix remodeling, enhanced osteoclast activation, and an up-regulated receptor activator of nuclear factor (NF)-kB-ligand (RANKL)/osteoprotegerin (OPG) ratio. In summary, BPs may be an effective alternative therapy for reversing osteoporotic alterations in smokers, and the potential mechanism is through modulation of the RANKL/OPG ratio.

Highlights

Bone tissue maintains its integrity by continuously regenerating itself tissue [1]
According to fluorescence staining microscopy, we found multinucleated osteoclasts in the co-culture, proving that osteoclastic differentiation was successfully induced by osteoblast secretions in our co-culture system
Cells were unable to remain viable in mono-cultures after 10 days, whereas cell viability was maintained in co-cultures (Figure 1B)

Summary

Introduction

Bone tissue maintains its integrity by continuously regenerating itself tissue [1]. In general, approximately 10% of the mineralized bone is renewed every year. A balance between the bone-forming cells and the bone-resorbing cells is crucial to bone homeostasis. Osteoblasts as the bone-forming cells play a dominant role in bone formation and regulate osteoclast differentiation through soluble factors and cognate interactions, which result in bone resorption [2]. The mechanisms regulating communication between osteoblasts and osteoclasts are demanding to the field of bone cell biology. When trying to decipher the mechanisms underlying bone homeostasis, it is insufficient to study osteoblasts and osteoclasts separately. Co-culture models become mandatory in order to obtain better insight into the interactions between osteoblasts and osteoclasts [3]. Certain technical challenges relating to co-culture models remain to be conquered, such as cell line compatibility, distinguishing between cell types, and selecting proper readouts [4]

Methods

Results

Conclusion