Intragland Shh gene delivery mitigated irradiation-induced hyposalivation in a miniature pig model

Abstract

Irreversible hypofunction of salivary glands is common in head and neck cancer survivors treated with radiotherapy and can only be temporarily relieved with current treatments. We found recently in mouse models that transient activation of Hedgehog pathway following irradiation rescued salivary gland function by preserving salivary stem/progenitor cells, parasympathetic innervation and microvessels. Due to huge differences between salivary glands of rodents and humans, to examine the translational potential of this approach, we evaluated effects of Shh gene transfer in a miniature pig model of irradiation-induced hyposalivation.Methods: The right parotid of each pig was irradiated with a single dose of 20 Gray. Shh and control GFP genes were delivered into irradiated parotid glands by noninvasive retrograde ductal instillation of corresponding adenoviral vectors 4 or 16 weeks after irradiation. Parotid saliva was collected every two weeks. Parotid glands were collected 5 or 20 weeks after irradiation for histology, Western blot and qRT-PCR assays.Results: Shh gene delivery 4 weeks after irradiation significantly improved stimulated saliva secretion and local blood supply up to 20 weeks, preserved saliva-producing acinar cells, parasympathetic innervation and microvessels as found in mouse models, and also activated autophagy and inhibited fibrogenesis in irradiated glands.Conclusion: These data indicate the translational potential of transient activation of Hedgehog pathway to preserve salivary function following irradiation.

CERE-120 Prevents Irradiation-Induced Hypofunction and Restores Immune Homeostasis in Porcine Salivary Glands

“…Multiple approaches targeting different cellular mechanisms have been developed to treat IR-induced hyposalivation in minipigs, such as AQP1 and Shh gene therapy and rapamycin drug therapy. 3 , 17 , 19 , 20 Only AQP1 gene therapy has progressed to phase I/II clinical trials in humans. 6 In the future, combination therapies that target different mechanisms may be required to prevent and repair IR-induced injury.…”

Insight into Salivary Gland Aquaporins

“…Viral gene delivery of sonic hedgehog has been shown to restore salivary secretion and AQP5 expression in irradiated mouse and minipig SG [ 157 , 158 , 159 ]. In addition, viral delivery of heat shock protein 25 showed similar effects in irradiated mouse SG [ 160 ].…”

Sphingosine‐1‐phosphate alleviates irradiation‐induced parotid injury in a miniature pig model

“…After the animals were anaesthetized and injected with pilocarpine (0.1 mg/kg), 10–20 min after injection, salivary flow rates were measured using modified Carlson–Crittenden cup connected to a mechanical vacuum device (Shanghai Zhang Dong Medical). The mechanical vacuum device was attached to the double‐sided mumps nipple, when forming a strand of clear saliva flowing down the mouth (Hu et al, ). In a 15‐ml centrifugal tube, over 10 min, two‐sided saliva was collected, and the saliva flow rate was recorded in ml/10 min.…”

“…Treatment of HNC with radiotherapy often leads to salivary gland hypofunction and xerostomia in long‐term HNC survivors (Jensen et al, ). Symptoms are often aggravated in a cumulative radiation dose‐dependent manner and subsequently cause a series of side effects, such as dysphagia, dental caries, impaired sense of taste and gastrointestinal diseases, which affect the prognosis and patients' quality of life (Hu et al, ).…”

“…However, some patients with HNC who receive irradiation (IR) still suffer from long‐term salivary gland injury (Ghosh‐Laskar et al, ). Gene therapy (Gao et al, ; Hu et al, ), stem cell treatment (Ejaz, Epperly, Hou, Greenberger, & Rubin, ) and molecular medicine (Hu et al, ) have been used to alleviate tissue damage associated with IR, but these strategies do not fulfil the clinical demands. Therefore, new techniques and strategies must be employed for the treatment of IR‐induced oral tissue injury.…”