Kinetic Model of Development and Aging of Artificial Skin Based on Analysis of Microscopy Data

Artificial human skin is available commercially or can be grown in the laboratory from established cell lines. Standard microscopy techniques show that artificial human skin has a fully developed basement membrane that separates an epidermis with the corneal, granular, spinosal, and basal layers from a dermis consisting of fibroblasts in an extracellular matrix. In this chapter, we show how modeling can integrate microscopy data to obtain a better understanding of the development and aging of artificial human skin. We use the time-dependent structural information predicted by our model to show how irradiation with an electron beam at different times in the life of artificial human skin affects the amount of energy deposited in different layers of the tissue. Experimental studies of this type will enable a better understanding of how different cell types in human skin contribute to overall tissue response to ionizing radiation

Radiobiological experiments for carbon ion prostate cancer therapy: Interplay of normal and tumor cells in co-culture and measurement of the oxygen enhancement ratio

Co-culture models are helpful to examine cell to cell interactions in vitro and to assess the cross-communication between two particular cell populations. Co-culture systems partially reflect the complex in vivo situation: in this study an in vitro co-culture model of prostate cancer cells {(Dunning R-3327-AT-1)} and small intestine cells {(intestinal epithelium cell line 6)} of the rat was established to simulate the carbon ion treatment of prostate cancer patient at GSI. Both cell lines were characterized in mono-cultures for their radio-biological response against 250 kVp x-rays and carbon ions of 270 MeV/u, 100 MeV/u, and 11.4 MeV/u, respectively. The parameters of the linear quadratic model, alpha and beta, for cell survival curves were determined as well as the relative biological effectiveness {(RBE)}. The measured RBE values were compared to calculations of the local effect model and were in agreement with the calculations. The RBEalpha increased stronger for the more radio-resistant prostate cancer cell line than for the epithelium cell line. The survival of unirradiated and irradiated cells from co-culture {(250 kVp x-rays, 100 MeV/u and 11.4 MeV/u carbon ions)} was compared to mono-cultures under the same conditions. The measured effects were attributed to irradiation independent as well as irradiation dependent factors. To study these effects, the inflammatory cytokines TGFbeta, TNFalpha, and IL-2 were analyzed, but their secretion was independent of radiation. To study the problem of hypoxic cells in tumor treatment a hypoxia chamber was developed in which cells were grown under defined oxygen status. Prostate cancer cells were irradiated with 250 kVp x-rays and carbon ions with a mean LET of 100 keV/µm under oxic and hypoxic conditions. The oxygen enhancement ratios for 10\% survival were found to be OER 2.35 for x-rays and 1.5 for carbon ions. The results of the co-culture model and the experiments under defined oxygen status are discussed in relation to ongoing prostate cancer therapy

Heterogeneity of γH2AX Foci Increases in Ex Vivo Biopsies Relative to In Vivo Tumors

The biomarker for DNA double stand breaks, gammaH2AX (γH2AX), holds a high potential as an intrinsic radiosensitivity predictor of tumors in clinical practice. Here, two published γH2AX foci datasets from in and ex vivo exposed human head and neck squamous cell carcinoma (hHNSCC) xenografts were statistically re-evaluated for the effect of the assay setting (in or ex vivo) on cellular geometry and the degree of heterogeneity in γH2AX foci. Significant differences between the nucleus areas of in- and ex vivo exposed samples were found. However, the number of foci increased linearly with nucleus area in irradiated samples of both settings. Moreover, irradiated tumor cells showed changes of nucleus area distributions towards larger areas compared to unexposed samples, implying cell cycle alteration after radiation exposure. The number of residual γH2AX foci showed a higher degree of intra-tumoral heterogeneity in the ex vivo exposed samples relative to the in vivo exposed samples. In the in vivo setting, the highest intra-tumoral heterogeneity was observed in initial γH2AX foci numbers (foci detected 30 min following irradiation). These results suggest that the tumor microenvironment and the culture condition considerably influence cellular adaptation and DNA damage repair

Endothelial Cell Response to Combined Photon or Proton Irradiation with Doxorubicin

Surgery, radiotherapy, and chemotherapy are essential treatment modalities to target cancer cells, but they frequently cause damage to the normal tissue, potentially leading to side effects. As proton beam radiotherapy (PBT) can precisely spare normal tissue, this therapeutic option is of increasing importance regarding (neo-)adjuvant and definitive anti-cancer therapies. Akin to photon-based radiotherapy, PBT is often combined with systemic treatment, such as doxorubicin (Dox). This study compares the cellular response of human microvascular endothelial cells (HMEC-1) following irradiation with photons (X) or protons (H) alone and also in combination with different sequences of Dox. The cellular survival, cell cycle, apoptosis, proliferation, viability, morphology, and migration were all investigated. Dox monotreatment had minor effects on all endpoints. Both radiation qualities alone and in combination with longer Dox schedules significantly reduced clonogenic survival and proliferation, increased the apoptotic cell fraction, induced a longer G2/M cell cycle arrest, and altered the cell morphology towards endothelial-to-mesenchymal-transition (EndoMT) processes. Radiation quality effects were seen for metabolic viability, proliferation, and motility of HMEC-1 cells. Additive effects were found for longer Dox schedules. Overall, similar effects were found for H/H-Dox and X/X-Dox. Significant alterations between the radiation qualities indicate different but not worse endothelial cell damage by H/H-Dox