Lgr5‐overexpressing mesenchymal stem cells augment fracture healing through regulation of Wnt/ERK signaling pathways and mitochondrial dynamics

Abstract

Fracture remains one of the most common traumatic conditions in orthopedic surgery. The use of mesenchymal stem cells (MSCs) to augment fracture repair is promising. Leucine‐rich repeat‐containing GPCR 5 (Lgr5), a transmembrane protein, has been identified as a novel adult stem cell marker in various organs and tissues. However, the roles of Lgr5 in MSCs are not fully understood. In this study, we investigated cellular functions of Lgr5 in MSCs and its potential implications in treating fracture. Lgr5‐overexpressing MSCs (MSCLgr5) were established in murine SV40 promoter–driven luciferase reporter MSC line through virus transfection. Results of real‐time quantitative PCR and Western blot analysis confirmed the increased expression of Lgr5 in MSCLgr5. MSCLgr5 exhibited increased osteogenic capacity, which may result from elevated expression of β‐catenin and phosphorylated ERK1/2 within the nuclear region of cells. In contrast, inhibition of Lgr5 expression decreased the osteogenic differentiation ability of MSCs, accompanied with increased mitochondrial fragmentation and reduced expression of β‐catenin. Local transplantation of MSCLgr5 at fracture sites accelerated fracture healing via enhanced osteogenesis and angiogenesis. MSCLgr5 stimulated the tube formation capacity of HUVECs in a Matrigel coculture system in vitro significantly. Taken together, results suggest that Lgr5 is implicated in the cellular processes of osteogenic differentiation of MSCs through regulation of Wnt and ERK signaling pathways and mitochondrial dynamics in fusion and fission. Inhibition of Lgr5 expression induced increased mitochondrial fragmentation and suppression of osteogenesis. MSCLgr5 exhibited enhanced therapeutic efficacy for fracture healing, which may serve as a superior cell source for bone tissue repair.—Lin, W., Xu, L., Pan, Q., Lin, S., Feng, L., Wang, B., Chen, S., Li, Y., Wang, H., Li, Y., Wang, Y., Lee, W. Y. W., Sun, D., Li, G. Lgr5‐overexpressing mesenchymal stem cells augment fracture healing through regulation of Wnt/ERK signaling pathways and mitochondrial dynamics. FASEB J. 33, 8565–8577 (2019). http://www.fasebj.org

Molecular Insights Into Lysyl Oxidases in Cartilage Regeneration and Rejuvenation

“…Aging-associated destruction of joints and cartilage degradation in osteoarthritis is correlated with changes in extracellular matrix of articular cartilage, such as cartilage ECM stiffness, and in the levels and solubility profiles of matrix crosslinks, especially pentosidine, as well as reduced thickness of cartilage, proteolysis, advanced glycation and calcification (Eyre et al, 1988;Pokharna et al, 1995;Lotz and Loeser, 2012). Notably, rejuvenation has emerged as a promising therapeutic regenerative approach for improvement or restoration of the self-repair capacity of injured or aging tissue and organ systems (Leung et al, 2006;Nelson et al, 2008;Luria and Chu, 2014;Sarkar et al, 2020), which has been proposed as a conversion into an embryonic-like state recapitulating many events during embryogenesis, including the reactivation of embryonic signature genes, and cytoskeletal/ECM components, and lineage specification (Vortkamp et al, 1998;Jankowski et al, 2009;Luo et al, 2009;Adam et al, 2015;Caldwell and Wang, 2015;Hu et al, 2017;Ransom et al, 2018;Feng et al, 2019;Lin W. et al, 2019;Miao et al, 2019). Consistently, the process of cartilage repair has been considered as recapitulation of various events during developmental morphogenesis.…”

Mitochondrial Dynamics: Fission and Fusion in Fate Determination of Mesenchymal Stem Cells

“…Injection of a miR-214 inhibitor or overexpression of Mfn2 can counteract the therapeutic effect of ASCs in rat urinary tissues (Wu et al, 2017). Local application of lgr5-overexpression MSCs at the fracture site is reported as a superior method in augmenting bone healing in mice because of the positive regulation of mitochondrial dynamics and Wnt/ERK signaling pathways (Lin et al, 2019).…”

Exosomal miRNA-128-3p from mesenchymal stem cells of aged rats regulates osteogenesis and bone fracture healing by targeting Smad5

“…Several cell types are involved in the dynamic modeling and remodeling process of bone tissue [6]. Among all the potential factors involved in bone metabolism, the differentiation capacity of bone marrow-derived mesenchymal stem cells (MSCs) is recognized to play quite a critical role [7][8][9]. Lineage specific differentiation of bone marrow stem cells is crucial to tissue repair.…”