Light-driven biofabrication of 3D stem-cell chondrogenic tissue analogues

关节软骨（AC）缺陷是全球数百万人行动不便和生活质量差的主要原因之一。目前的医学治疗已被证明是不够的长期再生的AC缺陷。另外，生物打印在组织工程（TE）中的应用允许通过多个细胞和生物材料的精确空间沉积来制造复杂的3D结构。当与人类多能干细胞（hPSCs）结合时，生物打印开辟了产生人类含软骨的组织替代品的可能性，然后可以将其移植到AC缺陷中并产生软骨来修复缺陷。软骨。尽管取得了重大进展，但目前的hPSCs向软骨细胞分化的方案仍然存在一些挑战，包括高成本，诱导因子批次之间的差异，施用生长因子和细胞受体表达的精确时间以及途径激活的精度差。基于先前的工作[1]，我们假设通过使用光遗传学，结合光学和遗传方法来控制细胞信号传导和表型，对软骨形成调控至关重要的细胞信号传导受体可以被工程光敏受体取代，允许通过特定光波长激活信号传导。这将使光对生物3D打印细胞负载水凝胶的分化进行精确微调。如果成功，这种创新的方法将首次实现具有高时空精度的细胞信号传导途径的动态操纵。

Articular cartilage (AC) defects are one of the major causes of immobility and poor quality of life for millions of individuals worldwide. Current medical therapies have proven to be insufficient for the long-term regeneration of AC defects. Alternatively, the application of bioprinting in tissue engineering (TE) allows for the fabrication of complex 3D constructs via the precise spatial deposition of multiple cells and biomaterials. When integrated with human pluripotent stem cells (hPSCs), bioprinting opens up the possibility to generate human chondroprogenitor-containing tissue substitutes that can then be transplanted into AC defects and produce cartilage to repair the defect. cartilage. Despite significant progress, the current differentiation protocols for hPSCs towards chondrocytes still present several challenges, including the high cost, inducing factor batch to batch variation and precise timing of administered growth factors and cellular receptor expression together with poor precision of pathway activation. Based on previous work [1], we hypothesise that through using optogenetics, which combines optical and genetic approaches to control cell signalling and hence phenotype, cell-signalling receptors that are critical for regulation of chondrogenesis can be replaced with engineered light sensitive receptors, allowing activation of signalling by specific light wavelengths. This will enable precision fine-tuning of differentiation in 3D bioprinted cell-laden hydrogels by light. If successful, this innovative approach would enable, for the first time, the dynamic manipulation of cell signalling pathways with high spatio-temporal precision.