Increased Potential of Bone Formation with the Intravenous Injection of a Parathyroid Hormone-Related Protein Minicircle DNA Vector.

Jang-Woon Kim,Jaewoo Kang,Narae Park,Hyerin Jung,Yena Kim,Ji Hyeon Ju,Yeri Alice Rim

doi:10.3390/ijms22169069

Abstract

Osteoporosis is commonly treated via the long-term usage of anti-osteoporotic agents; however, poor drug compliance and undesirable side effects limit their treatment efficacy. The parathyroid hormone-related protein (PTHrP) is essential for normal bone formation and remodeling; thus, may be used as an anti-osteoporotic agent. Here, we developed a platform for the delivery of a single peptide composed of two regions of the PTHrP protein (1–34 and 107–139); mcPTHrP 1–34+107–139 using a minicircle vector. We also transfected mcPTHrP 1–34+107–139 into human mesenchymal stem cells (MSCs) and generated Thru 1–34+107–139-producing engineered MSCs (eMSCs) as an alternative delivery system. Osteoporosis was induced in 12-week-old C57BL/6 female mice via ovariectomy. The ovariectomized (OVX) mice were then treated with the two systems; (1) mcPTHrP 1–34+107–139 was intravenously administered three times (once per week); (2) eMSCs were intraperitoneally administered twice (on weeks four and six). Compared with the control OVX mice, the mcPTHrP 1–34+107–139-treated group showed better trabecular bone structure quality, increased bone formation, and decreased bone resorption. Similar results were observed in the eMSCs-treated OVX mice. Altogether, these results provide experimental evidence to support the potential of delivering PTHrP 1–34+107–139 using the minicircle technology for the treatment of osteoporosis.

Highlights

Osteoporosis is a bone disease characterized by the loss of bone strength that leads to fragility fractures, which are accompanied by a decrease in the thickness of trabecular bones [1,2]
Reverse transcriptionpolymerase chain reaction (RT-PCR) analysis further confirmed the expression of PTH-related peptide (PTHrP) 1–34+107–139 in HEK293T cells 48 h post-transfection (Figure 1E)
Due to the small size of the insert (282 bp), we confirmed the potential false-positives caused by vector contamination in 48 h post-transfected cells by performing room temperature (RT)-PCR without the presence of reverse transcriptase (Supplementary Figure S1)

Summary

Introduction

Osteoporosis is a bone disease characterized by the loss of bone strength that leads to fragility fractures, which are accompanied by a decrease in the thickness of trabecular bones [1,2]. Anabolic agents increase bone formation via osteoblast-mediated bone metabolism [7,8] Among these agents are the parathyroid hormone analogs and PTH-related peptide (PTHrP) analogs including teriparatide and abaloparatide, which are both FDA-approved [9,10,11,12,13,14]. Another study reported that recombinant hPTHrP 1–84 was more effective than hPTHrP 1–34 in the context of both renal calcium reabsorption and the stimulation of bone formation in the OVX mice [19] Despite these advantages, bone anabolic agents can induce adverse effects, including hypercalcemia and dizziness [20]. Optimization is still needed to improve the bone-targeted efficacy of transplanted MSCs, and to associate this strategy with newly developed drugs or gene therapies for postmenopausal osteoporosis [21,22]

Methods

Results

Discussion

Conclusion