Comparing CT perfusion with oxygen partial pressure in a rabbit VX2 soft-tissue tumor model

Hypoxia A Typical Target in Human Lung Cancer Therapy

Lung cancer (LC) is the leading cause of cancer-related death globally. Comprehensive knowledge of the cellular and molecular etiology of LC is perilous for the development of active treatment approaches. Hypoxia in cancer is linked with malignancy, and its phenotype is implicated in the hypoxic reaction, which is being studied as a prospective cancer treatment target. The hypervascularization of the tumor is the main feature of human LC, and hypoxia is a major stimulator of neo-angiogenesis. It was seen that low oxygen levels in human LC are a critical aspect of this lethal illness. However, as there is a considerable body of literature espousing the presumed functional relevance of hypoxia in LC, the direct measurement of oxygen concentration in Human LC is yet to be determined. This narrative review aims to show the importance and as a future target for novel research studies that can lead to the perception of LC therapy in hypoxic malignancies.

Detection of Hypoxia in Cancer Models: Significance, Challenges, and Advances

The rapid proliferation of cancer cells combined with deficient vessels cause regions of nutrient and O2 deprivation in solid tumors. Some cancer cells can adapt to these extreme hypoxic conditions and persist to promote cancer progression. Intratumoral hypoxia has been consistently associated with a worse patient prognosis. In vitro, 3D models of spheroids or organoids can recapitulate spontaneous O2 gradients in solid tumors. Likewise, in vivo murine models of cancer reproduce the physiological levels of hypoxia that have been measured in human tumors. Given the potential clinical importance of hypoxia in cancer progression, there is an increasing need to design methods to measure O2 concentrations. O2 levels can be directly measured with needle-type probes, both optical and electrochemical. Alternatively, indirect, noninvasive approaches have been optimized, and include immunolabeling endogenous or exogenous markers. Fluorescent, phosphorescent, and luminescent reporters have also been employed experimentally to provide dynamic measurements of O2 in live cells or tumors. In medical imaging, modalities such as MRI and PET are often the method of choice. This review provides a comparative overview of the main methods utilized to detect hypoxia in cell culture and preclinical models of cancer.

Direct Quantification and Comparison of Intratumoral Hypoxia following Transcatheter Arterial Embolization of VX2 Liver Tumors with Different Diameter Microspheres

PURPOSE

To evaluate the effect of embolic diameter on achievement of hypoxia after embolization in an animal model of liver tumors.

MATERIALS AND METHODS

Inoculation of VX2 tumors in the left liver lobe was performed successfully in 12 New Zealand white rabbits weighing 3.7 kg ± 0.5 (mean ± SD). Tumors were deemed eligible for oxygen measurements when the maximum transverse diameter measured 15 mm or more by ultrasound examination. Direct monitoring of oxygenation of implanted rabbit hepatic VX2 tumors was performed with a fiberoptic electrode during and after transarterial embolization of the proper hepatic artery to angiographic flow stasis with microspheres measuring 70-150 μm, 100-300 μm, or 300-500 μm in diameter.

RESULTS

Failure to achieve tumor hypoxia as defined despite angiographic flow stasis was observed in 10 of 11 animals. Embolization microsphere size effect failed to demonstrate a significant trend on hypoxia outcome among the diameters tested, and pair-wise comparisons of different embolic diameter treatment groups showed no difference in hypoxia outcome. All microsphere diameters tested resulted in similar absolute reduction (24.3 mm Hg ± 18.3, 29.1 mm Hg ± 1.8, and 19.9 mm Hg ± 9.3, P = .66) and percentage decrease in oxygen (56.0 mm Hg ± 23.9, 56.0 mm Hg ± 6.4, and 35.8 mm Hg ± 20.6, P = .65). Pair-wise comparisons for percent tumor area occupied by embolic agents showed a significantly reduced fraction for 300-500 μm diameters compared with 70-150 μm diameters (P < .05).

CONCLUSIONS

In the rabbit VX2 liver tumor model, three tested microsphere diameters failed to cause tumor hypoxia as measured by a fiberoptic probe sensor according to the adopted hypoxia definitions.

In vivo remodelling of vascularizing engineered tissues

A critical aspect of creating vascularized tissues is the remodelling that occurs in vivo, driven in large part by the host response to the tissue construct. Rather than a simple inflammatory response, a beneficial tissue remodelling response results in the formation of vascularised tissue. The characteristics and dynamics of this response are slowly being elucidated, especially as they are modulated by the complex interaction between the biomaterial and cellular components of the tissue constructs and the host. This process has elements that are similar to both wound healing and tumour development, and its features are illustrated by reference to the bottom-up generation of a tissue using modular constructs. These modular constructs consist of mesenchymal stromal cells (MSC) embedded in endothelial cell (EC)-covered collagen gel rods that are a few hundred microns in size. Particular attention is paid to the role of hypoxia and macrophage recruitment, as well as the paracrine effects of the MSC and EC in this host response.

Pushing CT and MR imaging to the molecular level for studying the "omics": current challenges and advancements

During the past decade, medical imaging has made the transition from anatomical imaging to functional and even molecular imaging. Such transition provides a great opportunity to begin the integration of imaging data and various levels of biological data. In particular, the integration of imaging data and multiomics data such as genomics, metabolomics, proteomics, and pharmacogenomics may open new avenues for predictive, preventive, and personalized medicine. However, to promote imaging-omics integration, the practical challenge of imaging techniques should be addressed. In this paper, we describe key challenges in two imaging techniques: computed tomography (CT) and magnetic resonance imaging (MRI) and then review existing technological advancements. Despite the fact that CT and MRI have different principles of image formation, both imaging techniques can provide high-resolution anatomical images while playing a more and more important role in providing molecular information. Such imaging techniques that enable single modality to image both the detailed anatomy and function of tissues and organs of the body will be beneficial in the imaging-omics field.