02528nas a2200397   4500000000100000000000100001008004100002260001500043653001600058653001000074653001500084653001400099653001700113653001100130100001700141700002100158700002000179700001600199700002000215700002000235700002100255700001800276700002000294700001900314700002000333700003100353700002300384700001600407700001400423700001900437245006000456856011500516490000700631520147800638022001402116       2025                            d  c2025-10-3010aBioprinting10alabor10amyometrium10aPregnancy10atissue model10aUterus1 aCraig Ulrich1 aKorrina Siddiqui1 aLexa K. Baldwin1 aWeijian Hua1 aJacob K. Kuklok1 aJada J. Okaikoi1 aLauren L. Parker1 aJuli Petereit1 aDave R. Quilici1 aGrace M. Silva1 aAnutr Sivakoses1 aJiavanna S. Wong-Fortunato1 aRebekah J. Woolsey1 aAdrian West1 aYifei Jin1 aHeather Burkin00aA bioprinted model of pregnant human uterine myometrium  uhttps://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2025.1632320/full0 v133 aDespite decades of research, complications associated with dysfunctional labor are leading causes of maternal and neonatal morbidity. Currently available experimental models are not sufficient to understand the complex mechanisms underlying human labor nor to test new therapeutic approaches. We sought to develop a bioprinted tissue model of pregnant human myometrium that replicates the morphological, contractile and molecular characteristics of native pregnant human uterine myometrium as a resource to accelerate basic discovery and pharmacological testing. We have utilized primary human uterine smooth muscle cells to bioprint myometrial tissue rings containing >75% viable cells with elongated, smooth muscle morphology. Immunofluorescence confirmed expression of smooth muscle markers (caldesmon, alpha smooth muscle actin, and smooth muscle myosin), contractile-associated proteins (oxytocin receptor, prostaglandin receptors and connexin-43), and steroid hormone receptors (estrogen and progesterone receptors) characteristic of pregnant human uterine myometrium. Bioprinted tissues contracted in response to physiological agonists oxytocin (p < 0.001), prostaglandin F2α (p = 0.003), and prostaglandin E2 (p < 0.001), and relaxed in response to the nitric oxide donor S-nitrosoglutathione (p = 0.004). Further development of this model could provide an abundant and homogeneous tissue source to facilitate mechanistic studies and test agents to modulate labor.  a2296-4185