IGFBP3 deposited in the human umbilical cord mesenchymal stem cell‐secreted extracellular matrix promotes bone formation

Abstract

The extracellular matrix (ECM) contains rich biological cues for cell recruitment, proliferationm, and even differentiation. The osteoinductive potential of scaffolds could be enhanced through human bone marrow mesenchymal stem cell (hBMSC) directly depositing ECM on surface of scaffolds. However, the role and mechanism of human umbilical cord mesenchymal stem cells (hUCMSC)‐secreted ECM in bone formation remain unknown. We tested the osteoinductive properties of a hUCMSC‐secreted ECM construct (hUCMSC‐ECM) in a large femur defect of a severe combined immunodeficiency (SCID) mouse model. The hUCMSC‐ECM improved the colonization of endogenous MSCs and bone regeneration, similar to the hUCMSC‐seeded scaffold and superior to the scaffold substrate. Besides, the hUCMSC‐ECM enhanced the promigratory molecular expressions of the homing cells, including CCR2 and TβRI. Furthermore, the hUCMSC‐ECM increased the number of migrated MSCs by nearly 3.3 ± 0.1‐fold, relative to the scaffold substrate. As the most abundant cytokine deposited in the hUCMSC‐ECM, insulin‐like growth factor binding protein 3 (IGFBP3) promoted hBMSC migration in the TβRI/II‐ and CCR2‐dependent mechanisms. The hUCMSC‐ECM integrating shRNA‐mediated silencing of Igfbp3 that down‐regulated IGFBP3 expression by approximately 60%, reduced the number of migrated hBMSCs by 47%. In vivo, the hUCMSC‐ECM recruited 10‐fold more endogenous MSCs to initiate bone formation compared to the scaffold substrate. The knock‐down of Igfbp3 in the hUCMSC‐ECM inhibited nearly 60% of MSC homing and bone regeneration capacity. This research demonstrates that IGFBP3 is an important MSC homing molecule and the therapeutic potential of hUCMSC‐ECM in bone regeneration is enhanced by improving MSC homing in an IGFBP3‐dependent mechanism.

Regeneration enhanced in critical‐sized bone defects using bone‐specific extracellular matrix protein

“…BM‐ECM tissue culture substrates have been previously investigated 28,42,43 and found to be an improved cell culture environment to preserve the stem‐ness of cultured cells by providing a cell‐free extracellular matrix compared to regular tissue culture plates containing one or a select few extracted and purified ECM proteins 44 . Comparative studies evaluating cell proliferation rate, cell size, and cell surface markers of MSCs cultured on the BM‐ECM matrix versus other commercially available coated dishes exhibited more rapid proliferation, smaller cell size, and higher expression of certain stem cells markers in BM‐ECM tissue cultured plates than in the other products 19,28,42,43,45 . Having been produced from bone marrow MSCs rather than other standard matrix producing cells (fibroblasts), 46,47 BM‐ECM tissue culture substrates can be considered to be the more biologically niche‐relevant ECM for inducing osteogenesis.…”

“…39 As shown in Figure 5b, smaller cell size, and higher expression of certain stem cells markers in BM-ECM tissue cultured plates than in the other products. 19,28,42,43,45 Having been produced from bone marrow MSCs rather than other standard matrix producing cells (fibroblasts), 46,47 BM-ECM tissue culture substrates can be considered to be the more biologically nicherelevant ECM for inducing osteogenesis.…”

IGF2 enhanced the osteo‐/dentinogenic and neurogenic differentiation potentials of stem cells from apical papilla

“…65 Meanwhile, IGFBP3 is an important MSC homing molecule in bone regeneration in an IGFBP3-dependent mechanism. 66 HSPA13 is a member of the Hsp70 family of ATPase heat-shock proteins, which have been previously implicated in prion propagation. 67 These evidences demonstrated that IGF2 could enhance the functional protein secretion in microenvironment to promote cell proliferation and differentiation abilities of SCAPs.…”

“…IGFBP3 is the most abundant insulin‐like growth factor receptor in the serum and binds the majority of insulin‐like growth factors 65. Meanwhile, IGFBP3 is an important MSC homing molecule in bone regeneration in an IGFBP3‐dependent mechanism 66. HSPA13 is a member of the Hsp70 family of ATPase heat‐shock proteins, which have been previously implicated in prion propagation 67.…”

A selected small molecule prevents inflammatory osteolysis through restraining osteoclastogenesis by modulating PTEN activity

“…Calcium nodules are produced by osteoblasts during the mineralization of the extracellular matrix. 37 Thus, ARS staining was performed to investigate the effects of compound 17 on osteogenic differentiation and mineralization. The results showed that the mineralization area of the plate was promoted in the compound 17-treated groups compared to the control groups ( Figure 6A).…”