With an aging world population, there is an increased risk of fracture and impaired healing. One contributing factor may be aging‐associated decreases in vascular function; thus, enhancing angiogenesis could improve fracture healing. Both bone morphogenetic protein 2 (BMP‐2) and thrombopoietin (TPO) have pro‐angiogenic effects. The aim of this study was to investigate the effects of treatment with BMP‐2 or TPO on the in vitro angiogenic and proliferative potential of endothelial cells (ECs) isolated from lungs (LECs) or bone marrow (BMECs) of young (3‐4 months) and old (22‐24 months), male and female, C57BL/6J mice. Cell proliferation, vessel‐like structure formation, migration, and gene expression were used to evaluate angiogenic properties. In vitro characterization of ECs generally showed impaired vessel‐like structure formation and proliferation in old ECs compared to young ECs, but improved migration characteristics in old BMECs. Differential sex‐based angiogenic responses were observed, especially with respect to drug treatments and gene expression. Importantly, these studies suggest that NTN1, ROBO2, and SLIT3, along with angiogenic markers (CD31, FLT‐1, ANGPT1, and ANGP2) differentially regulate EC proliferation and functional outcomes based on treatment, sex, and age. Furthermore, treatment of old ECs with TPO typically improved vessel‐like structure parameters, but impaired migration. Thus, TPO may serve as an alternative treatment to BMP‐2 for fracture healing in aging owing to improved angiogenesis and fracture healing, and the lack of side effects associated with BMP‐2.
Clinical and animal studies have reported the influence of sex on the incidence and progression of tendinopathy, which results in disparate structural and biomechanical outcomes. However, there remains a paucity in our understanding of the sex‐specific biological mechanisms underlying effective tendon healing. To overcome this hurdle, our group has investigated the impact of sex on tendon regeneration using the super‐healer Murphy Roths Large (MRL/MpJ) mouse strain. We have previously shown that the scarless healing capacity of MRL/MpJ patellar tendons is associated with sexually dimorphic regulation of gene expression for pathways involved in fibrosis, cell migration, adhesion, and extracellular matrix (ECM) remodeling following an acute mid‐substance injury. Thus, we hypothesized that MRL/MpJ scarless tendon healing is mediated by sex‐specific and temporally distinct orchestration of cell–ECM interactions. Accordingly, the present study comparatively evaluated MRL/MpJ tendon cells on two‐dimensional (2D; glass) and scaffold platforms to examine cell behavior under biochemical and topographical cues associated with tendon homeostasis and healing. Female MRL/MpJ cells showed reduced 2D migration and spreading area accompanied by enhanced mechanosensing, ECM alignment, and fibronectin‐mediated cell proliferation compared to male MRL/MpJ cells. Interestingly, female MRL/MpJ cells cultured on isotropic scaffolds showed diminished cell–ECM organization compared to male MRL/MpJ cells. Lastly, MRL/MpJ cells elicited enhanced cytoskeletal elongation and alignment, ECM deposition and organization, and connexin 43‐mediated intercellular communication compared to male B6 cells, regardless of culture condition or sex. These results provide insight into the cellular features conserved within the MRL/MpJ phenotype and potential sex‐specific targets for the development of more equitable therapeutics.
more » « less- NSF-PAR ID:
- 10419266
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Journal of Orthopaedic Research
- Volume:
- 41
- Issue:
- 10
- ISSN:
- 0736-0266
- Page Range / eLocation ID:
- p. 2273-2286
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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