Engineering human spinal microphysiological systems to model opioid-induced tolerance

pioids are commonly used for treating chronic pain.However,with continued use,they may induce tolerance and/or hyperalgesia,which limits therapeutic efficacy.The human mechanisms of opioid-induced tolerance and hyperalgesia are significantly understudied,in part,because current models cannot fully recapitulate human pathology.Here,we engineered novel human spinal microphysiological systems(MPSs)integrated with plug-and-play neural activity sensing for modeling human nociception and opioid-induced tolerance.Each spinal MPS consists of a flattened human spinal cord organoid derived from human stem cells and a 3D printed organoid holder device for plug-and-play neural activity measurement.We found that the flattened organoid design of MPSs not only reduces hypoxia and necrosis in the organoids,but also promotes their neuron maturation,neural activity,and functional development.We further demonstrated that prolonged opioid exposure resulted in neurochemical correlates of opioid tolerance and hyperalgesia,as measured by altered neural activity,and downregulation ofμ-opioid receptor expression of human spinal MPSs.The MPSs are scalable,cost-effective,easy-to-use,and compatible with commonly-used well-plates,thus allowing plug-and-play measurements of neural activity.We believe the MPSs hold a promising translational potential for studying human pain etiology,screening new treatments,and validating novel therapeutics for human pain medicine.

Ultrasonic Chinese herbal medication penetration therapy at Tiānshū(天枢 ST25) for opioid-induced constipation with liver stagnation and spleen deficiency

Objectives:To observe the clinical effect on opioid-induced constipation of liver stagnation and spleen deficiency treated with the ultrasonic penetration of the No.1 constipation herbal formula at Tiānshū(天枢ST25).Methods:A total of 126 patients that were in compliance with the inclusion criteria were randomized into an acupoint group(41 cases),a Chinese medication group(42 cases)and a western medication group(43 cases).In the acupoint group,the ultrasonic penetration of the No.1 constipation herbal formula at bilateral Tiānshū(天枢ST25)were given.In the Chinese herbal medication group,the No.1 constipation herbal formula was prescribed for oral administration.In the western medication group,polyethylene glycol electrolyte powder was prescribed for oral administration.The treatment was given once a day,for 14 days totally.Before and after treatment,the constipation symptom score,the score of the patient assessment of constipation quality of life(PAC-QOL),the situation of nitric oxide synthetase(NOS)in serum were observed in each group.The safety indicators in the observation included diarrhea,allergic reaction,liver dysfunction,skin lesions,etc.Results:A total of 122 cases accomplished the trial.The total effective rate was 82.5%in the acupoint group,80.48%in the Chinese medication group and 78.04%in the western medication group.The constipation symptoms were all relieved in the three groups,indicating the statistical significance as compared with those before treatment(P<0.01,P<0.05).In the acupoint group and the western medication group,the improvements in the three symptom items,i.e.distention or scurrying pain in the chest,hypochondriac region or the bilateral sides of the abdomen,depression or irritability and poor appetite,were better than the western medication group(P<0.01,P<0.05).The improvements in all of the symptoms in the acupoint group were better than the Chinese medication group(all P<0.05).The PACQOL score was improved in each group after treatment and it was different significantly in statistics as compared with that before treatment in each group.After treatment,the improvement of PAC-QOL score in the acupoint group and the Chinese medication group was better than that in the western medication group(both P<0.05),and the improvement in the acupoint group was better than the Chinese medication group(P<0.05).As to serum NOS,after treatment,it was different significantly as compared with that before treatment in each group(all P<0.05),the improvement in the acupoint group was better than that of either the Chinese medication group or the western medication group,indicating the statistical significance(both P<0.05).The incidence of adverse reaction in the acupoint group was less and different significantly as compared with the western medication group(P<0.01),and it was different statistically as compared with the Chinese medication group(P<0.05).Conclusion:The ultrasonic penetration of the No.l constipation herbal formula at Tiānshū(天枢ST25)is effective on opioid-induced constipation of liver stagnation and spleen deficiency.This therapy achieves the significant therapeutic effect and presents the good compliance in treatment.Hence,it deserves to be further promoted in clinical application.

Astrocytic pyruvate dehydrogenase kinase-lactic acid axis involvement in glia-neuron crosstalk contributes to morphine-induced hyperalgesia in mice

The activation of spinal astrocytes accounts for opioid-induced hyperalgesia(OIH),but the underlying mechanisms remain elusive.The presence of astrocyte-neuron lactate shuttle(ANLS)makes astrocytes necessary for some neural function and communication.The aim of this study was to explore the role of ANLS in the occurrence and maintenance of OIH.After 7 days consecutive morphine injection,a mice OIH model was established and astrocytic pyruvate dehydrogenase kinase 4(PDK4),phosphorylated pyruvate dehydrogenase(p-PDH)and accumulation of L-lactate was elevated in the spinal dorsal horn.Intrathecally administration of inhibitors of PDK,lactate dehydrogenase 5 and monocarboxylate transporters to decrease the supply of L-lactate on neurons was observed to attenuate hypersensitivity behaviors induced by repeated morphine administration and downregulate the expression of markers of central sensitization in the spinal dorsal horns.The astrocyte line and the neuronal line were co-cultured to investigate the mechanisms in vitro.In this study,we demonstrated that morphine-induced hyperalgesia was sustained by lactate overload consequent upon aberrant function of spinal ANLS.In this process,PDK-p-PDH-lactate axis serves a pivotal role,which might therefore be a new target to improve long-term opioid treatment strategy in clinical practice.

A Role for Transmembrane Protein 16C/Slack Impairment in Excitatory Nociceptive Synaptic Plasticity in the Pathogenesis of Remifentanil-induced Hyperalgesia in Rats

Remifentanil is widely used to control intraoperative pain. However, its analgesic effect is limited by the generation of postoperative hyperalgesia. In this study, we investigated whether the impairment of transmembrane protein 16C(TMEM16C)/Slack is required for a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic receptor(AMPAR) activation in remifentanil-induced postoperative hyperalgesia. Remifentanil anesthesia reduced the paw withdrawal threshold from 2 h to 48 h postoperatively,with a decrease in the expression of TMEM16C and Slack in the dorsal root ganglia(DRG) and spinal cord.Knockdown of TMEM16C in the DRG reduced the expression of Slack and elevated the basal peripheral sensitivity and AMPAR expression and function. Overexpression of TMEM16C in the DRG impaired remifentanilinduced ERK1/2 phosphorylation and behavioral hyperalgesia. AMPAR-mediated current and neuronal excitability were downregulated by TMEM16C overexpression in the spinal cord. Taken together, these findings suggest that TMEM16C/Slack regulation of excitatory synaptic plasticity via GluA1-containing AMPARs is critical in the pathogenesis of remifentanil-induced postoperative hyperalgesia in rats.