Photoacoustics enables earlier detection of melanoma
Combining photoacoustic tomography with a gold nanocage-based contrast agent enables high-resolution three-dimensional imaging of melanoma, the deadliest form of skin cancer. The imaging system – developed by Lihong Wang, Younan Xia and colleagues at Washington University in St. Louis – could enable earlier diagnosis of the disease and improve patient survival. While pure optical imaging of deep tissues is limited by light absorption and scattering, photoacoustic tomography – in which pulsed light incident upon tumours heats up the cancer cells and generates sound waves – can detect deep structures as sound scatters far less than light in tissue.
Xia developed a contrast agent comprising hollow gold nanocages tuned to absorb strongly at 780 nm, a wavelength that can penetrate up to several inches in the body. The nanocages are functionalized with a peptide that targets skin cancer cells. Experiments with mice revealed that this functionalization increased the tumour uptake of the nanocages fourfold. The contrast agent increased the photoacoustic signal from the melanoma by 36%. Subcutaneous mouse melanomas barely visible to the unaided eye were clearly seen in the photoacoustic images (ACS Nano 4 4559).
Stem cells regenerate damaged heart tissue…
Investigators at Mayo Clinic (Rochester, MN) have demonstrated that rationally guided human adult stem cells can effectively heal, repair and regenerate damaged heart tissue. The researchers obtained bone marrow-derived stem cells from heart-disease patients undergoing coronary bypass surgery. While stem cells isolated from patients normally have a limited capacity to repair the heart, cells from two of 11 individuals showed an unusual capacity for heart repair. Such cells demonstrated upregulated genetic transcription factors that helped identify a molecular signature identifying highly regenerative stem cells (J. Am. Coll. Cardiol. 56 721).
To boost the regenerative benefit of non-reparative patient stem cells, a cocktail of recombinant cardiogenic growth factors was used to induce this signature in these cells. Injection of such cells into mice with heart failure resulted in significant recovery in heart function, along with improved survival rate after one year, compared to mice treated with unguided stem cells or saline. "These findings provide proof-of-principle that 'smart' adult stem cells have added benefit in repairing the heart, providing the foundation for further clinical evaluation," said Mayo Clinic's Andre Terzic, senior investigator of the study. The pre-clinical data reported in this seminal paper have cleared the way for safety and feasibility trials in humans, which were recently conducted in Europe.
… and repair spinal cord injuries
Neural stem cells may be of benefit to individuals with severe spinal cord injury, according to work by a Japanese research team led by Kinichi Nakashima at Nara Institute of Science and Technology. In the study, mice with severe spinal cord injury were transplanted with neural stem cells and administered valproic acid, a drug used in the treatment of epilepsy. The valproic acid promoted the differentiation of the transplanted stem cells into neurons rather than glial cells. The combination therapy resulted in impressive restoration of hind limb function. The authors hope that this approach could be developed as an effective treatment for severe spinal cord injury (J. Clin. Invest. 120 3255).
In an accompanying commentary, Tamir Ben-Hur from Hadassah Hebrew University Medical School in Israel highlighted the impressive functional recovery attained using this approach, but cautioned that further work is needed before it can be determined whether this will work in human patients.
Molecular imaging helps predict treatment success
A series of studies published in the September issue of the Journal of Nuclear Medicine demonstrate how molecular imaging plays a critical role in planning and evaluating treatment for a broad spectrum of cancers. At Memorial Sloan-Kettering Cancer Center (New York, NY), researchers performed planar imaging and SPECT/CT on 148 patients with thyroid cancer. SPECT/CT provided information that reduced the need for additional cross-sectional imaging in 29 patients and redefined initial risk recurrence estimates in seven of 109 patients (J. Nucl. Med. 51 1361). Investigators at Ludwig-Maximilians-University, Germany, used PET/CT with 68Ga-DOTATATE to monitor patients with neuroendocrine tumours undergoing peptide receptor radionuclide treatment. Results of the study, which evaluated 33 patients at baseline and three months after treatment began, suggest that PET/CT may contribute to the early prediction of treatment outcome in such patients (J. Nucl. Med. 51 1349).
A team at the University of São Paulo Medical School in Brazil evaluated 104 patients with newly diagnosed Hodgkin lymphoma using fluorodeoxyglucose (FDG)-PET following two cycles of chemotherapy. During a median follow-up of 36 months, relapse or disease progression was seen in 22 patients, with PET proving an accurate predictor of event-free survival (J. Nucl. Med. 51 1337). Researchers at the Netherlands Cancer Institute evaluated the use of PET for assessing treatment response in patients with non-small cell lung cancer. In a study of 23 patients treated with EGFR-TKI, a molecular-targeted agent, FDG PET/CT was used to monitor disease before and one week after drug administration. Results suggest that FDG-PET/CT can predict treatment response early in the therapy course (J. Nucl. Med. 51 1344).
OCT enhances angioplasty balloon manufacturing
Integrating an intravascular optical coherence tomography (OCT) probe into a computerized balloon deployment system could help improve angioplasty, a treatment for patients with a blocked coronary artery. Angioplasty involves threading a balloon-tipped tube from an artery in the groin to the coronary artery and then inflating the balloon to compress the blockage. Such balloons can also be used to deploy stents to keep the artery open. OCT, which images over a depth of a few millimetres, enabled precise monitoring of balloon inflation in the deployment tester. Rotation and translation of a catheter OCT probe in a balloon provided precise diameter and thickness measurements over the entire balloon (Rev. Sci. Instrum. 81 083101).
"Combining OCT with a balloon deployment system provides an improved platform for angioplasty balloon development and can also be used in the development of next-generation minimally invasive devices for percutaneous – through the skin – coronary interventions," said Guy Lamouche, research officer at the National Research Council of Canada. "It's now possible to monitor balloon inflation within an artery phantom or an excised artery to assess the efficiency of innovative balloon angioplasty or stent deployment procedures."