Pro-angiogenic potential of the isoxazole derivative ISO-1 via α7-nAChRs activation in human endothelial cells

Angiogenesis is essential for tissue growth and repair, but its dysregulation is associated with various pathological conditions, such as cancer and ischemic disease. Non-neuronal α7-nicotinic acetylcholine receptors (α7-nAChRs) mediate angiogenic pathways. Activation of these receptors increases endothelial Ca²⁺ concentration and stimulates intracellular signaling cascades involved in angiogenesis. The development of positive allosteric modulators and synthetic agonists targeting α7-nAChRs may serve as a strategy to enhance angiogenesis. The synthetic isoxazole compound ISO-1 acts as an α7-nAChR agonist, increasing endothelial Ca²⁺ concentrations. The aim of the present study was to evaluate the potential of ISO-1 to stimulate angiogenesis in vitro. HUVECs were isolated from umbilical cords. Cell viability, proliferation, migration and angiogenic capacity were assessed using MTS, neutral red, SRB, wound healing, and tube formation assays under treatment with ISO-1 and controls. ISO-1, at concentrations ranging from 1x10^-9 to 10^-3.5 M, did not affect endothelial viability. Regarding angiogenesis, ISO-1 did not stimulate endothelial cell proliferation but induced endothelial cell migration at concentrations of 10^-6 and 10^-4 M. This pro-migratory effect was similar to that observed with the activation of nAChRs by nicotine and choline. Furthermore, the effect was completely inhibited by the α7-nAChR antagonist α-bungarotoxin. ISO-1 increased tubular length and branching, similar to the effect of nicotine. These findings demonstrated that the isoxazole compound ISO-1, through activation of α7-nAChR, increased endothelial Ca²⁺ concentration and promoted endothelial cell migration and tubular formation, two key stages of angiogenesis. Altogether, these findings suggest that ISO-1 may represent a promising therapeutic candidate for diseases characterized by impaired angiogenesis. However, further investigations are needed to elucidate its precise downstream signaling pathways and in vivo efficacy.