Effect of Teriparatide Treatment on Mesenchymal Stromal Cells Functionality in Postmenopausal Osteoporotic Women with Atypical Femoral Fractures

Introduction

Teriparatide (TPTD) and abaloparatide are considered as a potential treatment option for patients experiencing Nitrogen-containing bisphosphonates (N-BP) associated atypical femoral fractures (AFF). TPTD is used to accelerate healing of different types of fractured bones, including AFF. Apart from its anabolic effect on bone, TPTD may improve stem-cell mobilization and expansion.

Aim

•  To study the effect of  TPTD treatment on quality and differentiation capacity of mesenchymal stromal cells (MSC) from bone marrow of patients with AFF

Patient Profile

• N=5
• Women of ages 65, 74, 75 (two) and 77 years, with atypical femoral fracture, treated with bisphosphonates for more than 5 years
• All patients had normal serum levels of vitamin D (25-hydroxyvitamin D or calcifediol) and adequate inhibition of bone remodeling markers
• Bone quality of all patients measured by bone microindentation was deeply deteriorated

Methods

• Patients received 0.266 mg calcifediol /month and 20 mg TPTD/day, via subcutaneous injections (SCI), for 6 months.

• MSC was isolated from bone marrow, before and after 6-month treatment
• All pre- and post-treatment Bone marrow mononuclear cells (BMMNC) were cryopreserved and maintained in the same way, to equalize experimental conditions.
• BMMNC of healthy donors from Hematology Service under Bone Marrow Transplantation Program at “Reina Sof?a University Hospital” were used as controls
• The presence of MSCs biochemical markers (CD73, CD90 and CD105 positive cells), gene expression of Homeobox protein NANOG, Sex-determining region Y (SRY) box 2 (SOX2) and Octamer-binding transcription factor 4 (OCT4), proliferation, senescence, and capacity to differentiate into osteoblasts and adipocytes were analyzed.
• Genes encoding lipoprotein (LPL) and fatty-acid-binding protein 4 (FABP4) were used as late molecular markers for adipogenesis and their expression was quantified for cells differentiating into adipocytes at day 10 after induction.

Results

• A significant increase of CD73 + CD90 + CD105 + cells was reported  after TPTD treatment (p < 0.05)
  • BMMNC positive cells for CD73, CD90 and CD105 increased from 6.5 to 37.5%
• NANOG, SOX2 and OCT4 were upregulated, being statistically significant for NANOG ( p< 0.05)
• Cells increased proliferative capacity more than 50% at day 7 (p< 0.05)
  • BMMNC proliferation was significantly higher in cells obtained in post-TPTD treatment of AFF patients after 4 and 7 days in culture.
  • Proliferation increased by 38.2 and 51.7% at days 4 and 7, respectively (p< 0.05).
• Senescence was significantly reduced by 2.5-fold (p< 0.05)
• At day 17 after TPTD treatment, BMMNC differentiation into adipocytes showed a significant increase of more than three-fold (p < 0.05),
• After TPTD treatment, expressions of runt-related transcription factor 2 (RUNX2) and integrin-binding sialoprotein (IBSP) osteoblastic genes significantly increased in BMMNC (p < 0.05)
• Genes encoding lipoprotein (LPL) and fatty-acid-binding protein 4 (FABP4) were significantly upregulated (p < 0.05), in BMMNC cultures derived from post-TPTD treatment

Conclusions

• TPTD had a positive effect on MSC populations of tested elderly patients with atypical fractures.
• It effectively increased cell number and overall functionality, including pluripotency and regenerative capacity of MSC, further favoring mobilization of other stem cells
• Six months of TPTD treatment was associated with improved bone health in these patients

• The findings indicate teriparatide potential as an activator agent of different regenerative processes in treatment of other pathologies

Calcif Tissue Int (2019). https://doi.org/10.1007/s00223-019-00533-0