The effect of morphine on endothelial differentiation of Vascular Mesenchimal Stromal Cells (vMSC)

In the field of illicit drug use, there is a great variability in prevalence mortality rates attributable to heroin overdose, but most studies on longitudinal trends of overdose deaths show increases across time. The most serious effect of opiates is the respiratory depression and pulmonary edema, whose cause is thought to be damage to the capillary endothelium, both ischemic and/or related to the direct toxic effect of the substance on entothelial cells. Tissue regeneration and repair are essential after endothelial cell injury and are related to the activity of human vascular mesenchimal stromal/stem cells (vMSCs), a versatile class of multipotent adult stem cells capable of self-renewal. The expression of opioid receptors on vMSCs has already been demonstrated; as a matter of fact, also an opiate-related impairment of vMSCs function might be a part of the pathophysiology of endothelial cell injury. The aim of this study was to assess the effect of in-vitro opiate exposure on the phisiologial activity and maintenance of human vMSCs. Cell viability, proliferative potential, oxidative stress and pro-senescence effect were evaluated in association with the ultrastructural analysis by transmission electron microscopy. In vitro vascular differentiation was also assessed, both by investigating the expression of the endothelial marker CD31 by immunofluorescence in cells exposed to VEGF and morphine sulphate; and by a tubular in vitro assay on geltrex matrix. Results showed clear cell impairment, including viability decrease, cytostatic and senescence effect as well as a state of cell cycle arrest and loss of replicative capacity for the highest concentrations tested. Although the results obtained must be considered only introductive to the related forensic issue, the forensic perpsectives have to consider the value of experimental data to assurge toward scientific evidence for application in caseworks and to provide a robust interpretation to the judicial questions in the forensic arena.