The ideal combination of hydrogel components for regeneration of cartilage and cartilaginous interfaces is a significant challenge because control over differentiation into multiple lineages is necessary. Stabilization of the phenotype of stem cell derived chondrocytes is needed to avoid undesired progression to terminal hypertrophy and tissue mineralization. A novel ternary blend hydrogel composed of methacrylated poly(ethylene glycol) (PEG), gelatin, and heparin (PGH) was designed to guide chondrogenesis by bone marrow derived mesenchymal stem cells (BMSCs) and maintenance of their cartilaginous phenotype. The hydrogel material effects on chondrogenic and osteogenic differentiation by BMSCs were evaluated in comparison to methacrylated gelatin hydrogel (GEL), a conventional bioink used for both chondrogenic and osteogenic applications. PGH and GEL hydrogels were loaded with goat BMSCs and cultured in chondrogenic and osteogenic mediums in vitro over six weeks. The PGH showed no sign of mineral deposition in an osteogenic environment in vitro. To further evaluate material effects, the hydrogels were loaded with adult human BMSCs (hBMSCs) and transforming growth factor β-3 and grown in subcutaneous pockets in mice over eight weeks. Consistent with the in vitro results, the PGH had greater potential to induce chondrogenesis by BMSCs in vivo compared to the GEL as evidenced by elevated gene expression of chondrogenic markers, supporting its potential for stable cartilage engineering. The PGH also showed a greater percentage of GAG positive cells compared to the GEL. Unlike the GEL, the PGH hydrogel exhibited anti-osteogenic effects in vivo as evidenced by negative Von Kossa staining and suppressed gene expression of hypertrophic and osteogenic markers. By nature of their polymer composition alone, the PGH and GEL regulated BMSC differentiation down different osteochondral lineages. Thus, the PGH and GEL are promising hydrogels to regenerate stratified cartilaginous interfacial tissues in situ, such as the mandibular condyle surface, using undifferentiated BMSCs and a stratified scaffold design.

中文翻译：

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水凝胶指导间充质干细胞的软骨形成与成骨，用于制造软骨组织。

用于软骨和软骨界面再生的水凝胶成分的理想组合是一项重大挑战，因为需要控制分化为多个谱系。需要稳定干细胞衍生的软骨细胞的表型，以避免不希望地进展为终末肥大和组织矿化。一种由甲基丙烯酸化聚乙二醇 (PEG)、明胶和肝素 (PGH) 组成的新型三元混合水凝胶旨在指导骨髓间充质干细胞 (BMSCs) 的软骨形成和软骨表型的维持。与甲基丙烯酸化明胶水凝胶 (GEL)（一种用于软骨形成和成骨应用的传统生物墨水）相比，评估了水凝胶材料对 BMSC 对软骨形成和成骨分化的影响。PGH 和 GEL 水凝胶装载山羊 BMSCs，并在体外软骨和成骨培养基中培养超过 6 周。PGH 在体外成骨环境中没有显示矿物质沉积的迹象。为了进一步评估材料效果，水凝胶加载了成人 BMSCs (hBMSCs) 和转化生长因子 β-3，并在小鼠皮下袋中生长超过 8 周。与体外结果一致，与 GEL 相比，PGH 在体内诱导 BMSCs 软骨形成的潜力更大，如软骨形成标志物的基因表达升高所证明，支持其稳定软骨工程的潜力。与 GEL 相比，PGH 还显示出更高百分比的 GAG 阳性细胞。与 GEL 不同的是，PGH 水凝胶在体内表现出抗成骨作用，如阴性 Von Kossa 染色和抑制肥大和成骨标志物的基因表达所证明的那样。仅凭其聚合物组成的性质，PGH 和 GEL 就可调节 BMSC 向不同骨软骨谱系的分化。因此，PGH 和 GEL 是有前途的水凝胶，可以使用未分化的 BMSC 和分层支架设计原位再生分层软骨界面组织，例如下颌骨髁表面。