State Key Laboratory of New Ceramics and Fine Processing, Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, No.1 Qinghuayuan Road, Beijing 100084, China; Department of Prosthodontics, School of Stomatology, Dalian Medical University, No.9 west section, Lvshunnan Road, Dalian 116044, China.
Institute of Orthopedics, The First Medical Center, Chinese PLA General Hospital, Beijing Key Lab of Regenerative Medicine in Orthopedics, Key Laboratory of Musculoskeletal Trauma and War Injuries PLA, No. 28 Fuxing Road, Haidian District, Beijing 100853, China.
Acta Biomater. 2022 Jul 1;146:94-106. doi: 10.1016/j.actbio.2022.05.012. Epub 2022 May 10.
Transforming growth factor-β (TGF-β) is an important inducing factor for the differentiation of mesenchymal stem cells and the secretion of collagen II, but the inaccessibility and instability limit its application in clinical practice. In this study, the TGF-β1-simulating peptide LIANAK (CM) was connected with the self-assembling peptide Ac-(RADA)-CONH (RAD) to obtain the functionalized self-assembling peptide Ac-(RADA)-GG-LIANAK-CONH (RAD-CM). The results indicated that the CM-functionalized RAD hydrogel contributed to the enhanced expressions of chondrogenic genes and extracellular matrix deposition. The self-assembling peptides were then combined with decellularized cartilage extracellular matrix (DCM) to construct a composite scaffold for articular cartilage repair. The CM-functionalized composite scaffold RAD/RAD-CM/DCM (R/C/D) exhibited good bioactivity and structural stability and exhibited satisfactory performance in promoting neocartilage restoration and the reconstruction of the osteochondral unit. This study provides a promising strategy for in situ cartilage regeneration via the stable presentation of TGF-β1-simulating peptide. STATEMENT OF SIGNIFICANCE: Deficiency of effective chondrogenic inducers (especially, the TGF-β family) significantly limits the self-regeneration of cartilage in osteochondral defect cases. Oligopeptide LIANAK, named CM, could simulate TGF-β1's bioactivity with particular structure, but traditional chemical crosslinking to polymer scaffolds resulted in risks of safety and complication, which is unfavorable for clinical applications. Here, self-assembling peptide RAD was used to load CM, to obtain a TGF-β1 mimetic peptide hydrogel. Depending on the homology (amino acids) of RAD and CM, the synthesis of the whole peptide only needs simply extended sequences of CM following that of RAD by automated solid-phase peptide synthesis. The modified peptide effectively demonstrated osteochondrogenic bioactivity, ensured the convenience, safety, and mass production, which displayed great potential in tissue engineering research and translational medicine.
转化生长因子-β（TGF-β）是间充质干细胞分化和胶原 II 分泌的重要诱导因子，但由于其不可及性和不稳定性，限制了其在临床实践中的应用。在本研究中，TGF-β1 模拟肽 LIANAK（CM）与自组装肽 Ac-（RADA）-CONH（RAD）相连，得到功能化的自组装肽 Ac-（RADA）-GG-LIANAK-CONH（RAD-CM）。结果表明，CM 功能化的 RAD 水凝胶有助于增强软骨基因的表达和细胞外基质的沉积。然后将自组装肽与脱细胞软骨细胞外基质（DCM）结合，构建用于关节软骨修复的复合支架。CM 功能化的复合支架 RAD/RAD-CM/DCM（R/C/D）具有良好的生物活性和结构稳定性，在促进新软骨修复和重建骨软骨单位方面表现出令人满意的性能。本研究为通过稳定呈现 TGF-β1 模拟肽实现原位软骨再生提供了一种有前途的策略。
有效的软骨诱导剂（尤其是 TGF-β 家族）的缺乏显著限制了骨软骨缺损情况下软骨的自我再生。短肽 LIANAK，命名为 CM，具有特殊的结构，可以模拟 TGF-β1 的生物活性，但是传统的化学交联聚合物支架存在安全性和并发症的风险，不利于临床应用。在这里，自组装肽 RAD 被用来负载 CM，得到一种 TGF-β1 模拟肽水凝胶。由于 RAD 和 CM 的同源性（氨基酸），整个肽的合成只需要通过自动化固相肽合成简单地将 CM 的序列延长到 RAD 之后。修饰后的肽有效地表现出成骨软骨生物活性，确保了方便性、安全性和大规模生产，在组织工程研究和转化医学方面具有巨大的潜力。
