Meng Guolong, Wu Xiaoli, Yao Ruijuan, He Jing, Yao Wu, Wu Fang
National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064, P.R. China.
Regen Biomater. 2019 Dec;6(6):349-359. doi: 10.1093/rb/rbz001. Epub 2019 Feb 8.
Zinc is an essential trace element required for bone remodelling process, but its role in such process remains to be elucidated. In particular, inconsistent results have been reported on the effect of Zn on osteoclastic responses, and supplement of receptor activator of nuclear factor kappa-B ligand (RANKL) factors has been commonly adopted. Co-culture is a suitable approach to elucidating the role of Zn in bone remodelling process, by better imitating the cellular environment as the presence of osteoblasts plays critical role in modulating osteoclastic functions. In this study, zinc-substituted HA coatings have been deposited using a liquid precursor plasma spraying process at two different concentrations (1, 2 wt.%). The effect of zinc substitution on osteoblastic and osteoclastic differentiation has been studied . In particular, a cultivation regime was designed to first induce osteoblastic differentiation of rat bone marrow stromal cells (BMSCs) for 14 days, and then induce osteoclastic differentiation of osteoclast-like precursor RAW 264.7 cells through the aid of the osteoblasts formed for additional 14 days, in the absence of the external addition of RANKL. The results showed that Zn substitution moderately promoted the BMSC differentiation into the osteoblasts and reduced the osteoclastic activity in early time (1 day co-culture). However, promotion of the osteoclastic activity were observed at later stages, as indicated by the significantly enhanced expressions of trap5b and IL-1 (8- and 15-day co-culture) and moderate stimulation of the nucleus integration and formation of the multinucleated cells (14-day co-culture). Such stimulating effect of the osteoclastic activity was absent under mono-culture of RAW 264.7 cell, with simple RANKL supplementation. The results suggest that both the zinc and the presence of MSC/osteoblast play profound and highly interacted roles on osteoclast differentiation and activity, which is critical in modulating the bone remodelling process.
锌是骨重塑过程所需的必需微量元素，但其在该过程中的作用仍有待阐明。特别是，关于锌对破骨细胞反应的影响，已有报道结果不一致，并且通常采用补充核因子κB受体活化因子配体（RANKL）因子的方法。共培养是一种合适的方法，可通过更好地模拟细胞环境来阐明锌在骨重塑过程中的作用，因为成骨细胞的存在在调节破骨细胞功能中起关键作用。在本研究中，使用液体前驱体等离子喷涂工艺以两种不同浓度（1%、2%重量比）沉积了锌取代的羟基磷灰石（HA）涂层。研究了锌取代对成骨细胞和破骨细胞分化的影响。具体而言，设计了一种培养方案，首先诱导大鼠骨髓间充质干细胞（BMSC）成骨分化14天，然后在不额外添加RANKL的情况下，借助已形成的成骨细胞再诱导破骨细胞样前体RAW 264.7细胞破骨分化14天。结果表明，锌取代适度促进了BMSC向成骨细胞的分化，并在早期（共培养1天）降低了破骨细胞活性。然而，在后期观察到破骨细胞活性增强，表现为trap5b和IL-1的表达显著增强（共培养8天和15天）以及多核细胞的核整合和形成受到适度刺激（共培养14天）。在RAW 264.7细胞单培养并简单补充RANKL的情况下，不存在这种对破骨细胞活性的刺激作用。结果表明，锌以及MSC/成骨细胞的存在对破骨细胞分化和活性均发挥着深远且高度相互作用的作用，这对调节骨重塑过程至关重要。
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