Peptide modified geniposidic acid targets bone and effectively promotes osteogenesis

Meijing Liu; Danqi Zhu; Fujun Jin; Shuang Li; Xiangning Liu; Xiaogang Wang

doi:10.1016/j.jot.2022.07.007

Peptide modified geniposidic acid targets bone and effectively promotes osteogenesis

J Orthop Translat. 2022 Oct 17:38:23-31. doi: 10.1016/j.jot.2022.07.007. eCollection 2023 Jan.

Authors

Meijing Liu^{1

2}, Danqi Zhu¹, Fujun Jin¹, Shuang Li¹, Xiangning Liu², Xiaogang Wang¹

Affiliations

¹ Key Laboratory of Big Data-Based Precision Medicine, School of Engineering Medicine, Beihang University, Beijing, 100191, China.
² Clinical Research Platform for Interdiscipline of Stomatology, The First Affiliated Hospital of Jinan University & Department of Stomatology, Jinan University, Guangzhou, 510632, PR China.

Abstract

Background: Geniposidic acid (GPA), one of the active components of Eucommia ulmoides, promote bone formation and treat osteoporosis by activating farnesoid X receptor (FXR). However, GPA has low oral availability and lack of bone targeting in the treatment of bone related diseases. With the development of modern technology, small molecules, amino acids, or aptamers are used for biological modification of drugs and target cells in bone tissue, which has become the trend of bone targeted research.

Methods: In this study, SDSSD (an osteoblast-targeting peptide) were modified in GPA using Fmoc solid-phase synthesis technique to form a new SDSSD-GPA conjugate (SGPA). The bone targeting of SGPA was evaluated using in vivo imaging and cell co-culture. In vitro, the effect of SGPA on cytotoxicity, osteoblastic activity, and mineralization ability were studied in mouse primary osteoblasts (OBs). In vivo, the therapeutic effect of SGPA on osteoporosis using an ovariectomized (OVX) mouse model. The bone mass, histomorphometry, serum biochemical parameters, and the molecular mechanism were evaluated.

Results: SGPA was enriched in OBs and tends to accumulate in bone tissue. In vitro, SGPA significantly enhanced the osteogenic activity and mineralization of OBs compared with GPA. In vivo, SGPA enhanced serum BALP and P1NP levels, increased the trabecular bone mass of the mice, and SGPA administration have a higher bone mineralization deposition rate than the GPA-treated mice. Moreover, SGPA significantly activated FXR and Runt-related transcription factor 2 (RUNX2).

Conclusions: Collectively, SGPA is enriched into OBs, and promotes bone formation by activating FXR-RUNX2 signalling, effectively treating osteoporosis at relatively low doses.

The translational potential of this article: This study demonstrates a more efficient and safe application of GPA in treating osteoporosis, provide a new concept for the bone targeted application of natural compounds.

Keywords: ALP, alkaline phosphatase; BALP, bone alkaline phosphatase; BMD, bone mineral density; BMSCs, bone marrow mesenchymal stem cells; BSEP, bile salt export pump; BV/TV, relative bone volume; Bone targeting; Ct.Th., cortical thickness; FXR, farnesoid X receptor; GPA, geniposidic acid; Geniposidic acid; MAR, mineral apposition rate; OBs, osteoblasts; OCN, osteocalcin; OSF-2, osteoblast-specific factor 2; OVX, ovariectomized; Osteogenesis; P1NP, procollagen type I N-terminal propeptide; Runx2, Runt-related transcription factor 2; SDSSD; SDSSD, Ser-Asp-Ser-Ser-Asp; SGPA, SDSSD-GPA conjugate; Tb.N., trabecular number.