In conclusion, elevated aminotransferase levels were associated with DHF/DSS and severe dengue in our cohort of adult patients with confirmed dengue. However, no threshold values discriminated between DF and DHF or between severe dengue and nonsevere dengue. Directed Fusion of Mesenchymal Stem Cells with Cardiomyocytes via VSV-G Facilitates Stem Cell Programming Mesenchymal stem cells (MSCs) spontaneously fuse with somatic cells in vivo, albeit rarely, and the fusion products are capable of tissue-specific function (mature trait) or proliferation (immature trait), depending on the microenvironment. That stem cells can be programmed, or somatic cells reprogrammed, in this fashion suggests that stem cell fusion holds promise as a therapeutic approach for the repair of damaged tissues, especially tissues not readily capable of functional regeneration, such as the myocardium. In an attempt to increase the frequency of stem cell fusion and, in so doing, increase the potential for cardiac tissue repair, we expressed the fusogen of the vesicular stomatitis virus (VSV-G) in human MSCs. We found VSV-G expressing MSCs (vMSCs) fused with cardiomyocytes (CMs) and these fusion products adopted a CM-like phenotype and morphology in vitro. In vivo, vMSCs delivered to damaged mouse myocardium via a collagen patch were able to home to the myocardium and fuse to cells within the infarct and peri-infarct region of the myocardium. This study provides a basis for the investigation of the biological impact of fusion of stem cells with CMs in vivo and illustrates how viral fusion proteins might better enable such studies. Mesenchymal stem cells (MSCs) show promise for therapeutic recovery of function of damaged myocardium [1] [2] [3] [4] [5] . MSCs home to injured tissues [6, 7] and contribute to the structure or functional recovery of the myocardium via (1) secretion of paracrine factors that can inhibit immune responses [8] and/or facilitate angiogenesis [7, 9, 10] , (2) transdifferentiation/metaplasia [11, 12] , and (3) nuclear reprogramming through fusion with resident cardiomyocytes (CMs) [13] . The latter has been largely dismissed since the frequency at which fusion is detected is low relative to the number of transplanted MSCs. However, recent studies by us [14] and others [15] [16] [17] suggest that despite the low frequency cell fusion still may exert a dramatic impact on stem cell programming or reprogramming in the heart.