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

关节软骨(AC)缺陷是导致全球数百万人行动不便和生活质量低下的主要原因之一。目前的医学治疗已被证明不足以长期再生AC缺陷。或者，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)整合后，生物打印为产生含有软骨前体的组织替代物提供了可能性，然后可以将其移植到AC缺损区，并产生软骨来修复缺损区。软骨。尽管取得了显著的进展，但目前的hPSCs向软骨细胞的分化方案仍然存在一些挑战，包括成本高，诱导因子批量变化，给予生长因子和细胞受体表达的精确时间，以及途径激活的精确度较低。基于以前的工作[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递，从而控制表型，对软骨形成调控至关重要的细胞信号受体可以被工程的光敏受体取代，从而允许通过特定的光波长激活信号。这将使通过光对3D生物打印细胞水凝胶的分化进行精确微调成为可能。如果成功，这种创新的方法将首次能够以高时空精度动态操纵细胞信号通路。

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.