Current saliva-based stimulation therapies for radiotherapy-induced xerostomia are not fully effective due to the presence of damaged secretory epithelia and nerves in the salivary gland (SG). Hence, three-dimensional bio-engineered organoids are essential to regenerate the damaged SG.

Herein, a recently validated three-dimensional (3D) biofabrication system, the magnetic 3D bioprinting (M3DB), is tested to generate innervated secretory epithelial organoids from a neural crest-derived mesenchymal stem cell, the human dental pulp stem cell (hDPSC). Cells are tagged with magnetic nanoparticles (MNP) and spatially arranged with magnet dots to generate 3D spheroids. Next, a SG epithelial differentiation stage was completed with fibroblast growth factor 10 (4–400 ng/ml) to recapitulate SG epithelial morphogenesis and neurogenesis. The SG organoids were then transplanted into ex vivo model to evaluate their epithelial growth and innervation.

M3DB-formed spheroids exhibited both high cell viability rate (>90%) and stable ATP intracellular activity compared to MNP-free spheroids. After differentiation, spheroids expressed SG epithelial compartments including secretory epithelial, ductal, myoepithelial, and neuronal. Fabricated organoids also produced salivary α-amylase upon FGF10 stimulation, and intracellular calcium mobilization and trans-epithelial resistance was elicited upon neurostimulation with different neurotransmitters. After transplantation, the SG-like organoids significantly stimulated epithelial and neuronal growth in damaged SG.

It is the first time bio-functional innervated SG-like organoids are bioprinted. Thus, this is an important step towards SG regeneration and the treatment of radiotherapy-induced xerostomia.

由于唾液腺（SG）中受损的分泌上皮和神经的存在，目前用于放射疗法引起的口干症的基于唾液的刺激疗法并不完全有效。因此，三维生物工程类器官对于再生受损的SG是必不可少的。

本文中，最近验证的三维（3D）生物制造系统，即磁性3D生物打印（M3DB），经过测试可从神经c衍生的间充质干细胞，即人类牙髓干细胞（hDPSC）生成神经支配的分泌上皮类器官。用磁性纳米粒子（MNP）标记细胞，并用磁铁点在空间上排列以生成3D球体。接下来，用成纤维细胞生长因子10（4–400 ng / ml）完成SG上皮分化阶段，以概括SG上皮的形态发生和神经发生。然后将SG类器官移植到离体模型中以评估其上皮生长和神经支配。

与不含MNP的球状体相比，M3DB形成的球状体显示出高的细胞存活率（> 90％）和稳定的ATP细胞内活性。分化后，球体表达SG上皮区室，包括分泌型上皮，导管，肌上皮和神经元。在FGF10刺激下，预制的类器官也产生唾液α-淀粉酶，并且在用不同的神经递质刺激神经后，会引起细胞内钙动员和跨上皮抵抗。移植后，SG样类器官极大地刺激了受损SG的上皮和神经元生长。

这是首次对生物功能化神经支配的SG状类器官进行生物印刷。因此，这是迈向SG再生和放射治疗引起的口干症治疗的重要一步。