The effects of bone morphogenetic protein 2 and thrombopoietin treatment on angiogenic properties of endothelial cells derived from the lung and bone marrow of young and aged, male and female mice

Abstract

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.

Commercial human pulmonary artery endothelial cells have in‐vitro behavior that varies by sex

“…In HUVECs, androgen treatment augments proliferation and migration in male but not female cell lines and this effect is mediated by the androgen receptor, 27 which could explain sex‐based differences in cardiovascular disease with aging. In murine lungs, there are age‐ and sex‐based differences in endothelial cell function, angiogenesis, and gene transcription regulating these pathways, 28 which may also influence human cellular phenotypes. Finally, we noticed substantial variation in behavior and function across cell lines supporting the concept that additional confounders (comorbid illness, BMI, etc.)…”

Insights into bone morphogenetic proteins in cardiovascular diseases

“…One study found that BMP-2 treatment decreases the migration of endothelial cells in both young and old mice, while endothelial cells from old mice showed better migration than those from young mice (Dadwal et al, 2021).…”

The Effects of SRT1720 Treatment on Endothelial Cells Derived from the Lung and Bone Marrow of Young and Aged, Male and Female Mice

“…Compared to LECs, BMECs exhibited significantly more angiogenic mRNA expression differences following treatment with SRT1720. We speculate that this may occur as LECs are isolated as a homogenous CD31+ population whereas BMECs are isolated as a heterogeneous population [ 45 , 46 , 47 , 48 , 49 ] that is comprised of mature and immature EC cells, stalk and tip cells, and perhaps EC-like cells that assist in EC function [ 11 ]. Exploring and comparing the gene profiles between these subpopulations of ECs remains to be investigated but is important to better understand how drugs would impact multiple cell types.…”

“…BMECs remained in this culture for seven days before being used for experiments. We have previously characterized BMECs isolated from this procedure by a number of criteria, including the examination of Tie2 expression (as evidenced in BMECs isolated from mice in which tdTomato is expressed under the control of the Tie2 promoter following activation with tamoxifen), CD31 immunocytochemical staining, and flow cytometric analysis (CD45- Ter119- CD31+ CD105+ cells) [ 47 , 48 , 49 ].…”