WNT-activated bone grafts repair osteonecrotic lesions in aged animals

Abstract

The Wnt pathway is a new target in bone therapeutic space. WNT proteins are potent stem cell activators and pro-osteogenic agents. Here, we gained insights into the molecular and cellular mechanisms responsible for liposome-reconstituted recombinant human WNT3A protein (L-WNT3A) efficacy to treat osteonecrotic defects. Skeletal injuries were coupled with cryoablation to create non-healing osteonecrotic defects in the diaphysis of the murine long bones. To replicate clinical therapy, osteonecrotic defects were treated with autologous bone graft, which were simulated by using bone graft material from syngeneic ACTB-eGFP-expressing mice. Control osteonecrotic defects received autografts alone; test sites received autografts treated ex vivo with L-WNT3A. In vivo µCT monitored healing over time and immunohistochemistry were used to track the fate of donor cells and assess their capacity to repair osteonecrotic defects according to age and WNT activation status. Collectively, analyses demonstrated that cells from the autograft directly contributed to repair of an osteonecrotic lesion, but this contribution diminished as the age of the donor increased. Pre-treating autografts from aged animals with L-WNT3A restored osteogenic capacity to autografts back to levels observed in autografts from young animals. A WNT therapeutic approach may therefore have utility in the treatment of osteonecrosis, especially in aged patients.

Wnt/β-catenin signalling promotes more effective fracture healing in aged mice than in adult mice by inducing angiogenesis and cell differentiation

“…Wnt signalling promotes bone formation by increasing the expression of proteins involved in osteogenic signalling, such RUNX2 and OCN. 27,40 Jing et al 41 developed a Wnt3a protein therapy to activate the Wnt pathway, thereby promoting transcription of osteogenic genes and accelerating fracture healing, 41,42 confirming these effects.…”

“…41 An increase in Wnt signalling increases the bone mineral density of aged people. 42,44 Therefore, stimulation of Wnt signalling is sufficient to overcome these age-related defects and represents a potential treatment for osteonecrosis and fractures in aged patients. 42 In our study, higher levels of LEF-1 and Osx mRNAs and greater numbers of BrdU-, RUNX2-and OCN-positive cells in the ROIs were observed in adult and aged CA mice than in adult and aged WT mice on day 14 after fracture.…”

Identifying the Potential Differentially Expressed miRNAs and mRNAs in Osteonecrosis of the Femoral Head Based on Integrated Analysis

“… 32 It is noted that liposome-reconstituted recombinant human WNT3A protein has been used to treat osteonecrosis defect. 33 The expression of DACT1 is found in primary chondrocytes and vascular endothelial cells. 34 , 35 Käkönen and Mundy 36 found that CSF-1 could interact with osteoblast to regulate the RANK–RANKL pathway to stimulate osteoclast precursors, ultimately leading to osteolysis.…”

“…32 It is noted that liposome-reconstituted recombinant human WNT3A protein has been used to treat osteonecrosis defect. 33 The expression of DACT1 is found in primary chondrocytes and vascular endothelial cells. 34,35 Käkönen and Figure 4 The sub-network of miRNA-target mRNAs between hsa-miR-378c, hsa-let-7a-5p, hsa-miR-28-5p, hsa-miR-3200-5p, hsa-miR-532-5p, and their targeted mRNAs in osteonecrosis of the femoral head.…”

Bioactivating a bone substitute accelerates graft incorporation in a murine model of vertical ridge augmentation

“…Wnt proteins rank amongst the most potent pro-osteogenic signals [ 42 – 44 ], which has directly led to the development of Wnt pathway activators for purposes of increasing bone mass [ 45 ] and accelerating bone repair [ 46 ]. For purposes of accelerating graft incorporation, however, systemic delivery of drugs such as romosozumab, an anti-Sclerostin antibody [ 47 ], is contraindicated because long-term use actually suppresses osteoprogenitor cell proliferation [ 48 ].…”