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Background: Persons living with human immunodeficiency virus (HIV) are at elevated risk of developing the malignant diseases that require allogeneic stem cell transplantation (ASCT). Recent data suggest that these individuals are also at an elevated risk of certain complications post-ASCT. This risk may result from preexisting HIV-related factors affecting dynamics of immune reconstitution post-ASCT. However, to date, there has been little work describing the dynamics of immune reconstitution post-ASCT in persons with HIV and none comparing these data to controls without HIV. Methods: We assessed T-cell reconstitution in 6 ASCT with HIV recipients (HIV+ASCT) compared to a control population of 21 ASCT without HIV recipients. In a subset of HIV+ASCT recipients we performed additional flow cytometry profiling of CD8+ T-cell subsets and antigen specificity of reconstituting CD4+ and CD8+ T cells. Results: We observe no difference in post-ASCT CD4+ T cells between HIV+ASCT and HIV-negative ASCT recipients, despite much lower pre-ASCT CD4+ T-cell counts in the HIV+ASCT group. In contrast, we observed significantly higher CD8+ T-cell numbers in the HIV+ASCT group post-ASCT. The reconstituting CD8+ T-cells were predominantly CD45RO+, whereas homing markers and antigen specificity of these cells varied between participants. Conclusion: This study represents the most extensive characterization of immune-reconstitution post-ASCT in persons with HIV, and the first to our knowledge to compare these data to ASCT controls without HIV. The results indicate that immune reconstitution in this group can be affected by preexisting HIV infection and post-ASCT antigen exposure.

Within the tumour stroma, a heterogeneous population of cell types reciprocally regulates cell proliferation, which considerably affects the progression of the disease. In this study, using tumour conditioned medium (TCM) derived from breast tumour cell lines – MCF7 and MDA MB 231, we have demonstrated the differentiation of adipose-derived mesenchymal stem cells (ADSCs) into tumour-associated fibroblasts (TAFs). Since the Wnt signalling pathway is a key signalling pathway driving breast tumour growth, the effect of the Wnt antagonist secreted frizzled-related protein 4 (sFRP4) was also examined. The response of ADSCs to TCM and sFRP4 treatments was determined by using cell viability assay to determine the changes in ADSC viability, immunofluorescence for mesenchymal markers, glucose uptake assay, and glycolysis stress test using the Seahorse Extracellular Flux analyser to determine the glycolytic activity of ADSCs. ADSCs have been shown to acquire a hyper-proliferative state, significantly increasing their number upon short-term and long-term exposure to TCM. Changes have also been observed in the expression of key mesenchymal markers as well as in the metabolic state of ADSCs. SFRP4 significantly inhibited the differentiation of ADSCs into TAFs by reducing cell growth as well as mesenchymal marker expression (cell line-dependent). However, sFRP4 did not induce further significant changes to the altered metabolic phenotype of ADSCs following TCM exposure. Altogether, this study suggests that the breast tumour milieu may transform ADSCs into a tumour-supportive phenotype, which can be altered by Wnt antagonism, but is independent of metabolic changes.

Tumours exhibit a heterogeneous mix of cell types that reciprocally regulate their growth in the tumour stroma, considerably affecting the progression of the disease. Both adipose-derived mesenchymal stem cells and Wnt signalling pathway are vital in driving breast tumour growth. Hence, we examined the effect of secreted factors released by adipose-derived mesenchymal stem cells, and further explored the anti-tumour property of the Wnt antagonist secreted frizzled-related protein 4 (sFRP4) on MCF-7 and MDA-MB-231 breast tumour cells. We observed that conditioned medium and extracellular matrix derived from adipose-derived mesenchymal stem cells inhibited tumour viability. The inhibitory effect of the conditioned medium was retained within its low molecular weight and non-protein component. The conditioned medium also induced apoptosis accompanied by a decrease in the mitochondrial membrane potential in tumour cells, Furthermore, it downregulated the protein expression of active ß-catenin and Cyclin D1, which are major target proteins of the Wnt signalling pathway, and reduced the expression of anti-apoptotic protein Bcl-xL. The combination of conditioned medium and sFRP4 further potentiated the effects, depending on the tumour cell line and experimental assay. We conclude that factors derived from conditioned medium of adipose-derived mesenchymal stem cells and sFRP4 significantly decreased the tumour cell viability and migration rates (MCF-7), accompanied with an enhanced apoptotic activity through inhibition of canonical Wnt signalling. Besides giving an insight to possible paracrine interactions and influence of signalling pathways, reflective of a breast tumour microenvironment, this study emphasises the utilization of cell free-secreted factors and Wnt antagonists to improve conventional anti-cancer strategies.