In vivo T-cell depletion with anti-thymocyte globulin (ATG) can attenuate GvHD but may increase infection and relapse risks. ATG-Fresenius (ATG-F) at a dose of 60 mg/kg was standard GvHD prophylaxis in unrelated donor hematopoietic stem cell transplantation (HSCT) at our institution. We changed to an incremental reduced dose regimen of 35 mg/kg and extended ATG prophylaxis to include older matched-related donor transplants considered to be at higher risk of GvHD. A total of 265 adults with hematological malignancies receiving a first allogeneic HSCT after myeloablative conditioning between 2009 and 2014 were analyzed in this cohort study. Patients had either received higher dose (n = 32) or lower dose ATG-F (n = 88) or no ATG (n = 145). ATG-F was associated with slower engraftment and less chronic GvHD, whereas no effect was noted on acute grade II-IV GvHD and relapse incidence. Transplant-related mortality (TRM) was lower and survival higher with lower dose, but not with higher dose ATG-F. Both ATG-F groups were associated with more viral reactivation, viral disease and bacterial blood stream infection, but not invasive fungal infection, and with slower immune reconstitution. The recently adopted strategy of using lower doses of ATG-F in unrelated and older age-related donor HSCT appears to reduce TRM without increasing disease relapse, leading to slightly enhanced survival.

Matrix metalloproteinases (MMPs) play an important role in modeling of the extracellular matrix. There is increasing evidence that these proteases are important in neurite elongation and axonal guidance during development in the central nervous system and retina. Moreover, they are also expressed after acute injury and can be the key mediators of pathogenesis. However, the role of MMPs in the inner ear is largely unknown. Our group recently demonstrated that general inhibition of MMPs resulted in auditory hair cell loss in vitro. In the present study, we investigated the role of MMPs in inner ear spiral ganglion neuron (SGN) survival, neuritogenesis and neurite extension by blocking MMPs known to be involved in axonal guidance, neurite elongation, and apoptosis in other neuronal systems. Spiral ganglion (SG) explants from 5-day-old Wistar rats were treated with different concentrations of the general MMP inhibitor GM6001, a specific MMP-2 inhibitor, and a specific MMP-9 inhibitor, in vitro. The general inhibitor of MMPs and the specific inhibition of MMP-2 significantly reduced both the number of neurites that extended from SG explants, as well as the length of individual neurites. However, neither the general inhibitor of MMPs nor the specific inhibition of MMP-2 influenced SGN survival. Inhibition of MMP-9 had no influence on SGNs. The data suggest that MMPs, and more specifically MMP-2, influence the growth of developing afferent neurites in the mammalian inner ear in vivo.