Weißenberger Manuel, Wagenbrenner Mike, Nickel Joachim, Ahlbrecht Rasmus, Blunk Torsten, Steinert Andre F, Gilbert Fabian
Department of Orthopaedic Surgery, Center for Musculoskeletal Research, Julius-Maximilians-University Würzburg, König-Ludwig-Haus, Würzburg, Germany.
Department of Orthopedic Surgery, University of Wuerzburg, König-Ludwig-Haus, Brettreichstraße 11, 97074, Würzburg, Germany.
J Exp Orthop. 2023 Mar 21;10(1):29. doi: 10.1186/s40634-023-00594-z.
Hypertrophic cartilage is an important characteristic of osteoarthritis and can often be found in patients suffering from osteoarthritis. Although the exact pathomechanism remains poorly understood, hypertrophic de-differentiation of chondrocytes also poses a major challenge in the cell-based repair of hyaline cartilage using mesenchymal stromal cells (MSCs). While different members of the transforming growth factor beta (TGF-β) family have been shown to promote chondrogenesis in MSCs, the transition into a hypertrophic phenotype remains a problem. To further examine this topic we compared the effects of the transcription growth and differentiation factor 5 (GDF-5) and the mutant R57A on in vitro chondrogenesis in MSCs.
Bone marrow-derived MSCs (BMSCs) were placed in pellet culture and in-cubated in chondrogenic differentiation medium containing R57A, GDF-5 and TGF-ß1 for 21 days. Chondrogenesis was examined histologically, immunohistochemically, through biochemical assays and by RT-qPCR regarding the expression of chondrogenic marker genes.
Treatment of BMSCs with R57A led to a dose dependent induction of chondrogenesis in BMSCs. Biochemical assays also showed an elevated glycosaminoglycan (GAG) content and expression of chondrogenic marker genes in corresponding pellets. While treatment with R57A led to superior chondrogenic differentiation compared to treatment with the GDF-5 wild type and similar levels compared to incubation with TGF-ß1, levels of chondrogenic hypertrophy were lower after induction with R57A and the GDF-5 wild type.
R57A is a stronger inducer of chondrogenesis in BMSCs than the GDF-5 wild type while leading to lower levels of chondrogenic hypertrophy in comparison with TGF-ß1.
肥大软骨是骨关节炎的一个重要特征，在骨关节炎患者中经常可以发现。尽管确切的发病机制仍不清楚，但软骨细胞的肥大去分化在使用间充质基质细胞（MSC）进行透明软骨的细胞修复中也构成了重大挑战。虽然转化生长因子β（TGF-β）家族的不同成员已被证明可促进MSC的软骨生成，但向肥大表型的转变仍然是一个问题。为了进一步研究这个课题，我们比较了转录生长和分化因子5（GDF-5）及其突变体R57A对MSC体外软骨生成的影响。
将骨髓来源的MSC（BMSC）置于微团培养中，在含有R57A、GDF-5和TGF-β1的软骨分化培养基中孵育21天。通过组织学、免疫组织化学、生化分析以及关于软骨生成标记基因表达的RT-qPCR来检测软骨生成。
用R57A处理BMSC导致BMSC软骨生成的剂量依赖性诱导。生化分析还显示相应微团中糖胺聚糖（GAG）含量升高以及软骨生成标记基因的表达。虽然与GDF-5野生型处理相比，用R57A处理导致了更好的软骨分化，并且与用TGF-β1孵育相比水平相似，但用R57A和GDF-5野生型诱导后软骨生成肥大水平较低。
与GDF-5野生型相比，R57A是BMSC软骨生成更强的诱导剂，同时与TGF-β1相比导致更低水平的软骨生成肥大。
