Despite the high prevalence of ischemic heart diseases worldwide, no antibody-based treatment currently exists. Starting from the evidence that a specific isoform of the Bone Morphogenetic Protein 1 (BMP1.3) is particularly elevated in both patients and animal models of myocardial infarction, here we assess whether its inhibition by a specific monoclonal antibody reduces cardiac fibrosis. We find that this treatment reduces collagen deposition and cross-linking, paralleled by enhanced cardiomyocyte survival, both in vivo and in primary cultures of cardiac cells. Mechanistically, we show that the anti-BMP1.3 monoclonal antibody inhibits Transforming Growth Factor β pathway, thus reducing myofibroblast activation and inducing cardioprotection through BMP5. Collectively, these data support the therapeutic use of anti-BMP1.3 antibodies to prevent cardiomyocyte apoptosis, reduce collagen deposition and preserve cardiac function after ischemia.

Bone morphogenetic proteins (BMPs) have a major role in tissue development. BMP3 is synthesized in osteocytes and mature osteoblasts and has an antagonistic effect on other BMPs in bone tissue. The main aim of this study was to fully characterize cortical bone and trabecular bone of long bones in both male and female Bmp3^−/− mice. To investigate the effect of Bmp3 from birth to maturity, we compared Bmp3^−/− mice with wild-type littermates at the following stages of postnatal development: 1 day (P0), 2 weeks (P14), 8 weeks and 16 weeks of age. Bmp3 deletion was confirmed using X-gal staining in P0 animals. Cartilage and bone tissue were examined in P14 animals using Alcian Blue/Alizarin Red staining. Detailed long bone analysis was performed in 8-week-old and 16-week-old animals using micro-CT. The Bmp3 reporter signal was localized in bone tissue, hair follicles, and lungs. Bone mineralization at 2 weeks of age was increased in long bones of Bmp3^−/− mice. Bmp3 deletion was shown to affect the skeleton until adulthood, where increased cortical and trabecular bone parameters were found in young and adult mice of both sexes, while delayed mineralization of the epiphyseal growth plate was found in adult Bmp3^−/− mice.

The relationship between hemochromatosis and diabetes has been well established, as excessive iron deposition has been reported to result in impaired function of the endocrine and exocrine pancreas. Therefore, the objective of the present study was to analyze the effects of iron accumulation on the pancreata and glucose homeostasis in a bone morphogenetic protein 6‑knockout (Bmp6^‑/‑) mouse model of hemochromatosis. The sera and pancreatic tissues of wild‑type (WT) and Bmp6^‑/‑ mice (age, 3 and 10 months) were subjected to biochemical and histological analyses. In addition, ¹⁸F‑fluorodeoxyglucose biodistribution was evaluated in the liver, muscle, heart, kidney and adipose tissue of both animal groups. The results demonstrated that 3‑month‑old Bmp6^‑/‑ mice exhibited iron accumulation preferentially in the exocrine pancreas, with no signs of pancreatic injury or fibrosis. No changes were observed in the glucose metabolism, as pancreatic islet diameter, insulin and glucagon secretion, blood glucose levels and glucose uptake in the liver, muscle and adipose tissue remained comparable with those in the WT mice. Aging Bmp6^‑/‑ mice presented with progressive iron deposits in the exocrine pancreas, leading to pancreatic degeneration and injury that was characterized by acinar atrophy, fibrosis and the infiltration of inflammatory cells. However, the aging mice exhibited unaltered blood glucose levels and islet structure, normal insulin secretion and moderately increased α‑cell mass compared with those in the age‑matched WT mice. Additionally, iron overload and pancreatic damage were not observed in the aging WT mice. These results supported a pathogenic role of iron overload in aging Bmp6^‑/‑ mice leading to iron‑induced exocrine pancreatic deficiency, whereas the endocrine pancreas retained normal function.

Previous studies have suggested a potential role of bone morphogenetic protein 6 (BMP6) in glucose metabolism, which also seems to be regulated by serotonin (5-hydroxytryptamine, 5HT), a biogenic amine with multiple roles in the organism. In this study, we explored possible interactions between BMP6, serotonin, and glucose metabolism regulation. The effect of BMP6 or 5HT on pancreatic β-cells has been studied in vitro using the INS-1 832/13 rat insulinoma cell line. Studies in vivo have been performed on mice with the global deletion of the Bmp6 gene (BMP6−/−) and included glucose and insulin tolerance tests, gene expression studies using RT-PCR, immunohistochemistry, and ELISA analyses. We have shown that BMP6 and 5HT treatments have the opposite effect on insulin secretion from INS-1 cells. The effect of BMP6 on the 5HT system in vivo depends on the tissue studied, with no observable systemic effect on peripheral 5HT metabolism. BMP6 deficiency does not cause diabetic changes, although a mild difference in insulin tolerance test between BMP6−/− and WT mice was observed. In conclusion, BMP6 does not directly influence glucose metabolism, but there is a possibility that its deletion causes slowly developing changes in glucose and serotonin metabolism, which would become more expressed with ageing.

Background: Ectopic bone formation models provide useful insights into bone tissue formation and remodeling processes. The use of a subcutaneous site emphasizes the focus on cytokine signaling and cell migration and proliferation while minimizing the effect of mechanical loading and direct interaction with surrounding stem cells. Methods: To study the effect of BMP3 on bone formation and remodeling, Bmp3^-/- mice were subcutaneously implanted with an autologous blood coagulum device containing BMP6, and bone formation was examined at days 7 and 14 post-implantation. Bone marrow cell composition was assessed using FACS. Formation of ectopic bone was analyzed using micro-CT, immunohistochemistry, and RNAseq to obtain transcriptomic data. Results: Bone marrow from Bmp3^-/- mice showed reduced lymphoid-lineage subsets, expanded myeloid lineage, and altered proportions of several osteochondroprogenitor subsets. A limited amount of newly formed bone tissue was seen in the implants after 7 days, while ectopic bone was more evident after 14 days, with significantly more bone in the Bmp3^-/- mice compared to WT mice. Localization of Sox9 and Runx2 showed a more advanced stage of bone tissue remodeling in Bmp3^-/- mice. Transcriptomic analysis showed upregulation of approximately 1700 genes on day 7 and 190 genes on day 14. Conclusions: These results suggest that BMP3 regulates the composition of bone and cartilage progenitor populations in bone marrow and consequently bone formation by arresting the remodeling of cartilage to bone tissue. The lack of BMP3 in ectopic bone accelerates the transition from the cartilaginous template to proper bone tissue.