Viral Inactivation of Human Osteochondral Grafts with Methylene Blue and Light

Assessment of bone dose response using ATR-FTIR spectroscopy: A potential method for biodosimetry

The health care application of ionizing radiation has expanded worldwide during the last several decades. While the health impacts of ionizing radiation improved patient care, inaccurate handling of radiation technology is more prone to potential health risks. Therefore, the present study characterizes the bone dose response using bovine femurs from a slaughterhouse. The gamma irradiation was designed into low-doses (0.002, 0.004 and 0.007 kGy) and high-doses (1, 10, 15, 25, 35, 50 and 60 kGy), all samples received independent doses. The combination of FTIR spectroscopy and PLS-DA allows the detection of differences in the control group and the ionizing dose, as well as distinguishing between high and low radiation doses. In this way, our findings contribute to future studies of the dose response to track ionizing radiation effects on biological systems.

Exosome mimicry by a HAVCR1-NPC1 pathway of endosomal fusion mediates hepatitis A virus infection

Cell-to-cell communication by exosomes controls normal and pathogenic processes^1,2. Viruses can spread in exosomes and thereby avoid immune recognition³. While biogenesis, binding and uptake of exosomes are well characterized^4,5, delivery of exosome cargo into the cytoplasm is poorly understood³. We report that the phosphatidylserine receptor HAVCR1 (refs. ^6,7) and the cholesterol transporter NPC1 (ref. ⁸) participate in cargo delivery from exosomes of hepatitis A virus (HAV)-infected cells (exo-HAV) by clathrin-mediated endocytosis. Using CRISPR-Cas9 knockout technology, we show that these two lipid receptors, which interact in the late endosome⁹, are necessary for the membrane fusion and delivery of RNA from exo-HAV into the cytoplasm. The HAVCR1-NPC1 pathway, which Ebola virus exploits to infect cells⁹, mediates HAV infection by exo-HAV, which indicates that viral infection via this exosome mimicry mechanism does not require an envelope glycoprotein. The capsid-free viral RNA in the exosome lumen, but not the endosomal uncoating of HAV particles contained in the exosomes, is mainly responsible for exo-HAV infectivity as assessed by methylene blue inactivation of non-encapsidated RNA. In contrast to exo-HAV, infectivity of HAV particles is pH-independent and requires HAVCR1 or another as yet unidentified receptor(s) but not NPC1. Our findings show that envelope-glycoprotein-independent fusion mechanisms are shared by exosomes and viruses, and call for a reassessment of the role of envelope glycoproteins in infection.

Large fresh osteochondral allografts of the knee: a systematic clinical and basic science review of the literature

PURPOSE

The aim of this study was to conduct an updated review of the literature regarding the clinical and basic science knowledge on osteochondral allograft transplantation in the knee for the treatment of large defects.

METHODS

According to specific criteria, 2 investigators systematically reviewed the literature for clinical and basic science reports regarding osteochondral allograft transplantation; data were independently extracted, pooled, and analyzed. Clinical and functional outcomes, International Knee Documentation Committee and Western Ontario and McMaster Universities Osteoarthritis Index scores, return to sport, quality of life, and survivorship of the grafts were assessed from the clinical articles. Regarding the basic science articles, the effects of allograft storage time, temperature, and different storage media were assessed.

RESULTS

Eleven articles reporting on clinical data and 14 articles reporting on basic science data (animal, cell, and biomechanical studies) were selected. The articles included in the review were not homogeneous, and different outcome measures were adopted. Overall excellent results were achieved, with improvement in all objective and subjective clinical scores, a high rate of return to sport, and a survivorship rate of 89% at 5 years. When multiple plugs were implanted, posterior grafts seemed to fail. Only 1 article compared fresh versus frozen grafts, with a greater improvement in scores in the frozen group. Cellular viability and number were reduced during storage, even at low temperatures; polyphenol from green tea and arbutin and higher temperatures favorably influenced cell viability of the cartilage during storage. On the other hand, the structural properties of the extracellular matrix were not influenced by the storage at low temperatures. Integration of the graft to the host was also important, and bony integration was usually achieved; however, on the cartilage side, integration was scant or did not occur, especially in the frozen grafts.

CONCLUSIONS

Fresh osteochondral allografts of the knee showed good clinical and functional outcomes even at longer-term follow-up. No other effective treatment exists, at the moment, for large osteochondral lesions. This surgical procedure is burdened by cost and difficulty in finding matching fresh donors. A new method to establish chondrocyte viability before the implantation of a new allograft would be a useful decision-making instrument.

LEVEL OF EVIDENCE

Level IV, systematic review of Level IV studies.